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Computed tomography in the diagnosis of pituitary adenoma
COMPUTED
TOMOGRAPHY IN THE DIAGNOSIS PITUITARY ADENOMA
OF
XING-RONG CHEN, TIAN-ZHEN SHEN, GONG-BAI CHEN and SHEN-SHENG TANG Hua Shari Hospital. 12 WulumugiZhong
Road. Shanghai.
200040.
People’s Republic of China
Abstract The CT scans of 85 cases of pituitary adenoma were studied and another 39 verified cases of other lesions in the sellar and parasellar region were also analyzed for comparison. The CT diagnosis and differential diagnosis were discussed and the policy for choosing the radiological diagnostic procedures for pituttary adenomas is mentioned. Computerized Cisternography
tomography
Pituitary
adenoma
Craniophaqngioma
Meningioma
Glloma
INTRODUCTION
Because of the presence of surrounding anatomical structures such as bone. brain, CSF and air in the sphenoid sinus which differ widely in attenuation on the one hand and the need to differentiate on the other, the diagnosis of pituitary adenoma with or without suprasellar extension has been considered a special challenge in computed tomography (CT) [l-6]. CT is still an effective method for evaluating patients with potential pituitary adenoma and other sellar or parasellar lesions. Our experience on the diagnosis and differential diagnosis of pituitary adenomas is presented as follows. METHODS
AND
MATERIALS
The study comprises 85 cases of pituitary adenomas. Forty-four cases have been operated on and of the pathological diagnosis made in each case. 20 were chromophobic adenoma, 13 were eosinophilic and chromophobic mixed adenoma, and 11 were eosinophilic adenoma: 41 cases were diagnosed by their typical endocrinologic changes and clinical manifestations. Another 39 cases (Table 1) which involved the sellar and parasellar region and were verified by operation and pathology were also analyzed for comparison. All of these cases were examined by CT from May 1979 to October 1980 in Hua Shan Hospital, Shanghai, People’s Republic of China. The CT examinations were performed on the CT-H2 head scanner with a 256 x 256 matrix. It takes approximately 2 min 50 set to perform one scan which reconstructs 2 contiguous images. The slice thickness was 10mm. At least 6 cuts of the pre-enhancement scan which contain the sellar region and its contiguous area were taken. Except for 2 patients who had a positive sensitivity test. all the other patients received 100 ml of 60”. glucamine diatrizoate (about 28 g of iodine) intravenously for enhancement and the sections through the sella were repeated. In 31 cases not only was
Table
I. Lesions involved the sellar and parasellar region __Number
Diagnosis Pituitary adenoma Craniopharyngioma Meningioma Glioma Hemangioma Chordoma Chondromyxoid fibroma Aneurysm Total
125
of cases
x5 ‘I x h
I I I I 124
Fig. 2
Fig. I
transverse tomography out in 7 cases.
performed,
but also coronal
sections.
Amipaque
cisternography
was carried
RESULTS The CT appearancrs
of
pituiturql adenomas
In the 85 cases of unenhanced scanning, the suprasellar cistern is obliterated in 10 cases and a filling defect is demonstrated in the anterior portion of the suprasellar cistern in 60 cases. The posterior margin of the filling defect is often shown clearly and its anterior margin often blended in with the base of frontal lobes (Fig. 1). In the 79 cases which revealed an abnormal suprasellar cistern, the density of the tumor region is homogenous (Fig. 2) in 53 cases (67.1’:;;) and nonhomogeneous in 26 cases (32.9’!,). In 53 cases with homogeneous lesions, the density is similar to the normal brain (35.4-40.8 H, average 39.0 H) in 47 cases (88.7?,,), that means these lesions are isodense. The density of the lesion is slightly higher than the normal brain, and the CT value is between 42-50 H in 6 cases (11.33,,); these lesions were hyperdense tumor (Fig. 3). In 26 cases with nonhomogeneous lesion, we find isodense areas mixed with low density regions (Fig. 5) in 6 cases (23.0:,{,) and isodensity mixed with high density lesion in 1 case (4.03,,). The low density area is often comparatively small and located in the center of the lesion. Occasionally it is located in an unusual position. As observed at operation, most of the low density areas correspond to the cystic change areas (Fig. 4 and 5) and some of them correspond to the necrotic areas. In the 85 cases. only 2 reveal tumor calcification (2.4”J. After intravenous injection of contrast media in 83 cases, the density of the lesion increases by 7-49.2 H in 81 cases (97.6’::) including 2 whose unenhanced study was negative. Compared with the original density of the lesions, the density increases 14.0- 144.7’:,, post contrast. Except for 9 cases (1 l.lp,,), all the increments in density are under 80”,,. After enhancement. the contour of the lesion and the cystic area are demonstrated more clearly. In the majority the suprasellar portions of the pituitary adenoma often present as round or oval shaped, but some are labulated (Fig. 6). The margin of the tumor usually is smooth and sharp (Figs 7 and 8). The size of the tumor usually is 2- 4 cm in diameter (Figs 8 and 9). but occasionally its diameter may reach 7 cm (Fig. 6). The anterior portion of the third ventricle is obliterated by tumor compression in 36 cases, of which the diameter of the tumor always exceeds 3 cm. When the tumor is larger, compression of the inner margin of the anterior horns of the lateral ventricles may be seen. In 2 cases. the tumor grows
127
Fig. 9
Fig. IO
superiorly and laterally beside the third ventricle. just like thalamic tumors. However, misdiagnosis can be avoided, because the tumor arises from the sella and the suprasellar cistern. In the coronal section, it can be clearly demonstrated that the tumor comes from the pituitary fossa and involves the suprasellar cistern, the anterior portion of the third ventricle and anterior horns of lateral ventricles (Fig. 10). However, fixing the patient’s head in this position is so difficult that the artifacts often make the images non-diagnostic. Cisternography was performed in 5 cases. The filling defects in the suprasellar cistern were seen in 4 cases (Fig. 11). The lesions which can be shown after enhancement only. and lesions which can be shown in the cisternography only. are the smaller ones whose diameter is often less than 2 cm. In another patient, all three studies (plain scan, the enhanced scan and cisternography) are negative, but the plain films show signs of intrasellar tumor and the empty sella has been ruled out by encephalogram. Therefore, this tumor has not grown up to the suprasellar cistern. To summarize, most of the pituitary tumors (89.9’:J growing up to the suprasellar cistern present the typical signs: they appear as a filling defect in the suprasellar cistern or obliterate this cistern on plain scan. Generally they are isodense lesions or their density is increased slightly. The cystic area is not often present or is comparatively small. After enhancement their density increases 25.3 H on average, and the increment in density less than 80”,,. Most of them are round or oval in shape and 2-~4 cm in diameter.
The suprasellar cistern is abnormal in all 21 cases of carniopharyngiomas. In 11 cases, the tumor presents itself as a low density lesion (about 25 H), the shape is round or oval and its width is 2.5 -5.Ocm. In 7 of these 11 cases a shell-like or ring-like calcification defined the margin of the lesion, and suggests that the wall of the cyst is calcified (Fig. 12). After the injection of contrast media, only the uncalcified part of the wall of the cyst is enhanced and presents as a curved or circular opaque line (Fig. 13). In 4 cases. a massive calcification larger than 1 cm is shown in the suprasellar cistern (Fig. 14). After enhancement there is not any change in the density of the lesions and in one of these 4 cases there is a cystic lucent area around the calcification. In one case the tumor presented as an isodense lesion with many dispersed calcified spots. This is similar to the rare pituitary adenoma with calcification, but the number of the calcified spots is much more than we see in pituitary adenoma. In this case after enhancement the density of the isodense part increases by 24 H. In 5 cases, before and after the enhancement the appearances of the tumor are similar to the typical appearances of the pituitary adenoma. In one of these 5 cases, the displacement of the circle of Willis is shown. In another of these 5 cases, a round filling defect 1.5 cm in diameter is revealed in
CT in the diagnosis
Fig. 1I
of pituitary
adenoma
Fig. 12
the suprasellar cistern on the cisternography. In addition, the larger tumor also caused a series of third and lateral ventricle changes which are similar to the pituitary adenoma in the suprasel lar cistern. In brief, most of the craniopharyngiomas (71.4”,,) show one of the following two kinds of typic :a1 is appearances: (1) the plain scanning, a low density lesion with shell-like or circular calcification demonstrated within the suprasellar cistern. After enhancement, a curved enhanced line may be seen along the non-calcified margin of the lesion. (2) A comparatively large massive calcification with or without low density area presents in the suprasellar cistern. Of course, about one fourth of t he craniopharyngiomas can’t be differentiated from the pituitary adenomas based only on the results of the CT scan. The CT apprarances
of meninyiomas
Meningiomas in the sella region come from the tuberculum sellae, diaphragma sellae and Ithe inner third of the sphenoidal ridge. In 4 cases, the appearances are different from pituitary adenor na,
Fig. 13
Fig. 14
Fig. IS
Fig. I6
the tumor is located in the suprasellar cistern eccentrically and is oval in shape. The margin of the tumor is smooth and sharp. The density of the plain scan is more than 50 H and therefore higher than the pituitary adenoma (Fig. 15). The density post-enhancement increases more than 50 H, and exceeds the usual increment in pituitary adenoma (Fig. 16). In 4 cases the pre- and post-enhanced appearances are similar to the pituitary adenoma. The CT appearances
qf’q1iomu.s
Of the 6 cases, 5 are gliomas of the anterior portion of the third ventricle and one is the glioma of the optic nerve. In the histological examination, one case is astrocytoma of grade three. Three cases are astrocytomas grade two and the other two cases are grade one. In all of the 6 cases. the anterior portion of the third ventricle is abnormal. The suprasellar cistern is normal in 2 cases and abnormal in 4 cases. In 5 cases the lesion is non-homogeneous. One has several calcified spots within the tumor (Fig. 17) and the others have a large low density component mixed with a small isodense component. The other case was an isodense lesion. Before the enhancement, the margin of the lesion is not clear-cut in 5 cases and fairly clear-cut in one. After the injection of contrast media, the density of the lesion increases slightly and irregularly. In one case the lesion is oval in shape (Fig. 18) and the others are irregular in shape. The cisternography was performed in one case and demonstrates the lesion is lobulated and irregular (Fig. 19). The CT uppearance
of other lesions
One hemangioma presents as a suprasellar lobulated high dense lesion, after the injection of contrast media its density increases for 102 H, its margin is very clear-cut, just like a high density meningioma (Figs 20 and 21). In one chordoma (Figs 22 and 23) and one chondromyxoid fibroma (Figs 24 and 25), the principal changes are bone hypertrophy and destruction, the intracranial soft tissue component is comparatively small, and in the chordoma a calcified mass is seen. The postenhancement scan of the chordoma is hardly differentiated from the pituitary adenoma. An aneurysm of the anterior communicating artery presents as a round filling defect in the suprasellar cistern (Fig. 26). After injection of the contrast media, the lesion is enhanced markedly (Figs 27 and 28).
DI
Fig. 18
Fig. 17
Fig. 19
Fig. 20
Fig. 22
Fig. 21 131
Fig. 23
Fig. 25
Fig. 74
Fig. 76
CT m the diagnosis of pittmary
adenoma
133
employed, the intrasellar pituitary adenoma can be shown 17, 81. When the pituitary adenoma involves the suprasellar cistern and the diameter of its suprasellar portion is larger than 2 cm it can be demonstrated easily by the pre- and post-enhancement CT. When the suprasellar portion of the tumor is smaller than 2 cm it may be missed by plain and enhanced scan, but it can be shown clearly by cisternography. Therefore, applying CT to localize the pituitary adenoma involving suprasellar cistern is very accurate. The appearance of tumors in the sellar and parasellar region is variable. Different features can present in one kind of tumor, and the same features can present in several kinds of tumors. Some lesions which are not tumors such as suprasellar aneurysms may also present features which can be seen in the pituitary adenoma. However. every kind of tumor in the sellar and parasellar region still has some special characteristics. According to our material, 89.9’5,) of the pituitary adenomas present the aforementioned typical CT appearances, and only a small number of craniopharyngiomas, meningiomas and gliomas share these appearances. Consequently, when these appearances are demonstrated, especially when the clinical manifestations of pituitary dysfunction and the findings of intrasellar tumor on the plain film are present, the diagnosis should be pituitary adenoma growing into the suprasellar cistern. Otherwise, the craniopharyngioma, meningioma or glioma should be considered depending on the appearance of the scan. Many craniopharyngiomas present the aforementioned two kinds of typical appearances. Based on these appearances, especially the shall-like or circular calcification and relatively large dense calcification in the suprasellar cistern. and furthermore if these findings occur in the young patient, the diagnosis of craniopharyngioma can be made with confidence. When craniopharyngioma presents as a rather large low density lesion, to differentiate it from the pituitary adenoma usually is not necessary. Of course, under this situation, it is very difficult to differentiate it from other cystic lesions such as arachnoid cyst and epidermoid cyst. The appearances of many meningiomas in the sellar and parasellar region are completely identical to the pituitary adenoma and the differential diagnosis between them is very difficult. But. it is noteworthy that the density of the lesion may be helpful to the differential diagnosis. We have a group of 25 cases of meningiomas proven by operation and pathology: half of them are highly dense lesions, in 6 cases (24.0?1,,) the density is higher than the high density pituitary adenomas in our group and the CT value is above 50 H, and after injection of contrast media the density increases much more than the pituitary adenoma. When these findings are encountered. we believe that the diagnosis of meningioma should be considered first, especially when it is located eccentrically and the patient does not have endocrine disorders. The majority of gliomas present as low density areas which occupy the main part of the lesion mixed with isodensity area. Its limits are not clear-cut in the pre- and post-enhancement. After the injection of contrast media, the density of the glioma increases non-homogeneously and its contour usually is irregular. Based on these appearances, it is easy enough to differentiate it from the pituitary adenoma. However, a part of the astrocytomas of first or second grade are very similar to the pituitary adenomas (Fig. 18). Bone tumors of the sellar region. such as the chondromyxoid fibroma and chordoma in this series and the metastatic bone tumors that mainly cause bone changes would rarely be misinterpreted as pituitary adenoma. Of course, it is very difficult to distinguish between the metastatic tumors which have invaded the brain deeply and pituitary adenomas which have destroyed the bone extensively. It is also very difficult to make a correct pathological diagnosis before operation on rare tumors and other lesions in the sellar and parasellar region, such as the hemangioma in this series. and the colloid cyst of third ventricle and ectopic pinealoma, etc. that are not contained in this series [9 I I]. Some of them may present appearances similar to the pituitary adenomas. Since the advent of CT the features of the radiological examination of the cranium and brain have been greatly changed. Because CT is a non-invasive and painless method, it has been used as a screening examination for brain tumors. There have been many radiological examinations for the diagnosis and differential diagnosis of the pituitary adenoma. but how to make the proper choice is very important. In our series, the plain films and the pre- and post-enhancement scanning (except 2 cases which are sensitive to the contrast media) have been made in all cases, cisternography CT has been performed in 7 cases, cerebral angiography has been carried out in 15 cases. pneumoencephalo-
134
YIN<,-ROX
(‘HF.%
CI
graphy has been performed in 7 cases and the water soluble contrast media ventriculography has been carried out in 2 cases. After analysis, we found that most pneumoencephalography and ventriculography and some of the cerebral arteriograms are superfluous and should be excluded. For the pituitary adenoma, we deem it necessary to take the plain films first. If the diagnosis cannot he decided, or the localization has not been clear, the size. range and character are not clear, then the CT scan is performed. When the patient has endocrine disorder. the CT scan is normal and plain film is negative or equivocal. then the multidirection tomography for the sella [ 121 has to be done in order to detect the pituitary microadenoma. When CT scanning cannot determine with certainty whether the suprasellar cistern is normal or not. especially when the plain film has demonstrated an enlarged sella, then cisternography CT or pneumoencephalography with multidirectional tomography 1131 may also be performed to rule out the empty sella and to determine if the pituitary adenoma has grown up into the suprasellar cistern. Further angiography should never be done, unless the encasement of the main blood vessel requires study and the aneurysm or the tumor with rich blood supply should be ruled out.
SUMMARY The CT appearance of 85 cases of pituitary adenoma were studied and another 39 verified cases of other lesions in the sellar and parasellar region were also analyzed for comparison. The common lesions involving the sellar and parasellar region are pituitary adenoma, craniopharyngioma, meningioma and glioma; among them the pituitary adenoma encompasses about 70’!,,. The appearances of lesions in the sellar and parasellar region are variable, different features can present in one kind of lesion and the same appearance can present in several kinds of lesions. However, each kind of the common lesions in this region still has some special identifying characteristics. In this series, 89.9O,, of the pituitary adenomas growing into the suprasellar cistern present typical signs. A filling defect in the suprasellar cistern or obliteration of this cistern are very common. The density of the lesion is the same as or a little bit higher than the normal brain. The cystic change area is not often present or is comparatively small. After injection of contrast media its density increases to 25.3 H on average and the increment is usually less than 80”,,. It is usually 2~-4 cm in diameter and round or oval in shape. Many craniopharyngiomas present as a low density lesion with shell-like calcification or relatively large calcified mass in the suprasellar cistern. It is hard to misinterpret them as a pituitary adenoma, especially in the young patient. The density of most meningiomas in the pre- and post-enhancement scan is much higher than the high density pituitary adenoma. This may be helpful to differentiate the meningioma from the pituitary adenoma. The majority of gliomas in the pre- and post-enhancement scan present as non-homogenous lesions with large low density areas and irregular and undefined margins. Based on these appearances, it is easy enough to differentiate it from the pituitary adenoma. However, it is worthy of notice that some of the common lesions and many of the rare lesions in the sellar and parasellar region may present an appearance similar to pituitary adenoma. Our policy about how to choose the procedures for the diagnosis of the pituitary adenoma is discussed. REFERENCES I. C. M. Citrin and D. 0. Davis. Computerized tomography in the evaluation of pituitary adenoma. Inres~. Rad. I, 27 35 (1977). 2. D. F. Danoff, S. Pripstein, N. Grace, S. Kramer and K. F. Lee, The value of computerized tomography in delineatmg suprasellar extension of pituitary adnoma for radiotherapeutic mangement. Cancer 42, 10661072 (1978). 3. C. Glydensted and A. Karle, Computed tomography of intra and juxtasellar lesions, 14, 5 13 (1977). 4. T. P. Naidich. T. P. R. S. Pinto, M. J. Kushner. J. P. Lin, 1. I. Kricheff. N. E. Leeds and N. E. Chase, Evaluatton of sellar and parasellar masses by computed tomography, Radiology 120, 91-99 (1976). 5. S. M. Wolpert, K. D. Post, B. J. Biller and M. E. Molitch, The value of computed tomography in evaluating patients with prolactinoma, Rudioloyy 131, 117-119 (1979). 6. A. Hatem. M. Bergstrom and T. Greitz, Diagnosis of sellar and parasellar lesions by computed tomography, Nwrorudiology 18, 2499258 (1979). 7. A. Syvertsen. V. M. Haughton, A. L. Williams and J. F. Cusick. The computed tomographic appearance of the normal pituitary gland and pituitary microadfenoma. Rudiolog~ 133, 385 391 (1979).
CT in the diagnosis
of pttuitary
I35
adenoma
8. I. 1. Kricheff, The radiology diagnosis of pituitary adenoma. Rrrdioloy~~ 131, 263 265. 1979. 9. N. E. Leeds and T. P. Naidich. Computerized tomography in the diagnosis of scllar and parasellar lessons. Scwin Romry. 12. 1’1-135 (1977). IO. D. I. Sung. L. Harisiadis and C. H. Chang. mtdline pineal tumors and suprasellar germinomas: high]) curable by irradiation. Rudioloy~ 128, 7455751 (1978). 1 I. A. B. Dublm A. B. and J. R. Youmans. Computer assisted ventriculography. J. Comput. trssi.sr. Tomogr. 2, 162 164 (1978). 13. W. D. Robertson and T. H. Newton. Radiologic assessment of pituitary microadenoma. .4rn. J. Rocwlgq. 131. 4X9 492 (1978). 13. J. C. Johnson, M. Lubow and J. Steam. Polytomoencephalographic of the optic chiasm and adjacent structures. Rtrdio/og~~ 114, 629-634 (1975). About the Author-TIAN-ZHEN SHEN M.D.. female, 41-yr old, graduated from College in 1963. Now, she is the attending doctor in Department of Radiology Shanghai First Medical College, Shanghai, China.
Shanghai of Hua
First Medical Shan Hospital.
CHEN M.D., male, 48-yr old, graduated from Shanghai First Medical College in 1955. Now, he is the chief of Department of Neurosurgery of Hua Shan Hospital, Shanghai First Medical College. Shanghai, China.
About the AuthorpGONG-BAI
the Author SHEN-SHENG TANG M.D.. male, 43-yr old, graduated from College in 1959. Now, he is the attending doctor in Department of Neurosurgery Shanghai First Medical College. Shanghai. China.
About
Shanghai First Medical of Hua Shan Hospital,
CHEN M.D.. 50-yr old. graduated from Shanghai First Medical College in 1956. Presently Chief. Department of Radiology, Hua Shan Hospital. after serving as Visiting Professor of Radiology at Downstate Medical Center. State University of New York during 198&1981. Member of the Chinese Radiological Society, Commissioner of the Cllimw Jowt~ol of’Radioloy,. Associate Editor of the R~fw~wu of rho Fowiyn Medicine. Radiological Fascicle. About the Author-XING-RONG
TOMOGRAPHY IN THE DIAGNOSIS PITUITARY ADENOMA
OF
XING-RONG CHEN, TIAN-ZHEN SHEN, GONG-BAI CHEN and SHEN-SHENG TANG Hua Shari Hospital. 12 WulumugiZhong
Road. Shanghai.
200040.
People’s Republic of China
Abstract The CT scans of 85 cases of pituitary adenoma were studied and another 39 verified cases of other lesions in the sellar and parasellar region were also analyzed for comparison. The CT diagnosis and differential diagnosis were discussed and the policy for choosing the radiological diagnostic procedures for pituttary adenomas is mentioned. Computerized Cisternography
tomography
Pituitary
adenoma
Craniophaqngioma
Meningioma
Glloma
INTRODUCTION
Because of the presence of surrounding anatomical structures such as bone. brain, CSF and air in the sphenoid sinus which differ widely in attenuation on the one hand and the need to differentiate on the other, the diagnosis of pituitary adenoma with or without suprasellar extension has been considered a special challenge in computed tomography (CT) [l-6]. CT is still an effective method for evaluating patients with potential pituitary adenoma and other sellar or parasellar lesions. Our experience on the diagnosis and differential diagnosis of pituitary adenomas is presented as follows. METHODS
AND
MATERIALS
The study comprises 85 cases of pituitary adenomas. Forty-four cases have been operated on and of the pathological diagnosis made in each case. 20 were chromophobic adenoma, 13 were eosinophilic and chromophobic mixed adenoma, and 11 were eosinophilic adenoma: 41 cases were diagnosed by their typical endocrinologic changes and clinical manifestations. Another 39 cases (Table 1) which involved the sellar and parasellar region and were verified by operation and pathology were also analyzed for comparison. All of these cases were examined by CT from May 1979 to October 1980 in Hua Shan Hospital, Shanghai, People’s Republic of China. The CT examinations were performed on the CT-H2 head scanner with a 256 x 256 matrix. It takes approximately 2 min 50 set to perform one scan which reconstructs 2 contiguous images. The slice thickness was 10mm. At least 6 cuts of the pre-enhancement scan which contain the sellar region and its contiguous area were taken. Except for 2 patients who had a positive sensitivity test. all the other patients received 100 ml of 60”. glucamine diatrizoate (about 28 g of iodine) intravenously for enhancement and the sections through the sella were repeated. In 31 cases not only was
Table
I. Lesions involved the sellar and parasellar region __Number
Diagnosis Pituitary adenoma Craniopharyngioma Meningioma Glioma Hemangioma Chordoma Chondromyxoid fibroma Aneurysm Total
125
of cases
x5 ‘I x h
I I I I 124
Fig. 2
Fig. I
transverse tomography out in 7 cases.
performed,
but also coronal
sections.
Amipaque
cisternography
was carried
RESULTS The CT appearancrs
of
pituiturql adenomas
In the 85 cases of unenhanced scanning, the suprasellar cistern is obliterated in 10 cases and a filling defect is demonstrated in the anterior portion of the suprasellar cistern in 60 cases. The posterior margin of the filling defect is often shown clearly and its anterior margin often blended in with the base of frontal lobes (Fig. 1). In the 79 cases which revealed an abnormal suprasellar cistern, the density of the tumor region is homogenous (Fig. 2) in 53 cases (67.1’:;;) and nonhomogeneous in 26 cases (32.9’!,). In 53 cases with homogeneous lesions, the density is similar to the normal brain (35.4-40.8 H, average 39.0 H) in 47 cases (88.7?,,), that means these lesions are isodense. The density of the lesion is slightly higher than the normal brain, and the CT value is between 42-50 H in 6 cases (11.33,,); these lesions were hyperdense tumor (Fig. 3). In 26 cases with nonhomogeneous lesion, we find isodense areas mixed with low density regions (Fig. 5) in 6 cases (23.0:,{,) and isodensity mixed with high density lesion in 1 case (4.03,,). The low density area is often comparatively small and located in the center of the lesion. Occasionally it is located in an unusual position. As observed at operation, most of the low density areas correspond to the cystic change areas (Fig. 4 and 5) and some of them correspond to the necrotic areas. In the 85 cases. only 2 reveal tumor calcification (2.4”J. After intravenous injection of contrast media in 83 cases, the density of the lesion increases by 7-49.2 H in 81 cases (97.6’::) including 2 whose unenhanced study was negative. Compared with the original density of the lesions, the density increases 14.0- 144.7’:,, post contrast. Except for 9 cases (1 l.lp,,), all the increments in density are under 80”,,. After enhancement. the contour of the lesion and the cystic area are demonstrated more clearly. In the majority the suprasellar portions of the pituitary adenoma often present as round or oval shaped, but some are labulated (Fig. 6). The margin of the tumor usually is smooth and sharp (Figs 7 and 8). The size of the tumor usually is 2- 4 cm in diameter (Figs 8 and 9). but occasionally its diameter may reach 7 cm (Fig. 6). The anterior portion of the third ventricle is obliterated by tumor compression in 36 cases, of which the diameter of the tumor always exceeds 3 cm. When the tumor is larger, compression of the inner margin of the anterior horns of the lateral ventricles may be seen. In 2 cases. the tumor grows
127
Fig. 9
Fig. IO
superiorly and laterally beside the third ventricle. just like thalamic tumors. However, misdiagnosis can be avoided, because the tumor arises from the sella and the suprasellar cistern. In the coronal section, it can be clearly demonstrated that the tumor comes from the pituitary fossa and involves the suprasellar cistern, the anterior portion of the third ventricle and anterior horns of lateral ventricles (Fig. 10). However, fixing the patient’s head in this position is so difficult that the artifacts often make the images non-diagnostic. Cisternography was performed in 5 cases. The filling defects in the suprasellar cistern were seen in 4 cases (Fig. 11). The lesions which can be shown after enhancement only. and lesions which can be shown in the cisternography only. are the smaller ones whose diameter is often less than 2 cm. In another patient, all three studies (plain scan, the enhanced scan and cisternography) are negative, but the plain films show signs of intrasellar tumor and the empty sella has been ruled out by encephalogram. Therefore, this tumor has not grown up to the suprasellar cistern. To summarize, most of the pituitary tumors (89.9’:J growing up to the suprasellar cistern present the typical signs: they appear as a filling defect in the suprasellar cistern or obliterate this cistern on plain scan. Generally they are isodense lesions or their density is increased slightly. The cystic area is not often present or is comparatively small. After enhancement their density increases 25.3 H on average, and the increment in density less than 80”,,. Most of them are round or oval in shape and 2-~4 cm in diameter.
The suprasellar cistern is abnormal in all 21 cases of carniopharyngiomas. In 11 cases, the tumor presents itself as a low density lesion (about 25 H), the shape is round or oval and its width is 2.5 -5.Ocm. In 7 of these 11 cases a shell-like or ring-like calcification defined the margin of the lesion, and suggests that the wall of the cyst is calcified (Fig. 12). After the injection of contrast media, only the uncalcified part of the wall of the cyst is enhanced and presents as a curved or circular opaque line (Fig. 13). In 4 cases. a massive calcification larger than 1 cm is shown in the suprasellar cistern (Fig. 14). After enhancement there is not any change in the density of the lesions and in one of these 4 cases there is a cystic lucent area around the calcification. In one case the tumor presented as an isodense lesion with many dispersed calcified spots. This is similar to the rare pituitary adenoma with calcification, but the number of the calcified spots is much more than we see in pituitary adenoma. In this case after enhancement the density of the isodense part increases by 24 H. In 5 cases, before and after the enhancement the appearances of the tumor are similar to the typical appearances of the pituitary adenoma. In one of these 5 cases, the displacement of the circle of Willis is shown. In another of these 5 cases, a round filling defect 1.5 cm in diameter is revealed in
CT in the diagnosis
Fig. 1I
of pituitary
adenoma
Fig. 12
the suprasellar cistern on the cisternography. In addition, the larger tumor also caused a series of third and lateral ventricle changes which are similar to the pituitary adenoma in the suprasel lar cistern. In brief, most of the craniopharyngiomas (71.4”,,) show one of the following two kinds of typic :a1 is appearances: (1) the plain scanning, a low density lesion with shell-like or circular calcification demonstrated within the suprasellar cistern. After enhancement, a curved enhanced line may be seen along the non-calcified margin of the lesion. (2) A comparatively large massive calcification with or without low density area presents in the suprasellar cistern. Of course, about one fourth of t he craniopharyngiomas can’t be differentiated from the pituitary adenomas based only on the results of the CT scan. The CT apprarances
of meninyiomas
Meningiomas in the sella region come from the tuberculum sellae, diaphragma sellae and Ithe inner third of the sphenoidal ridge. In 4 cases, the appearances are different from pituitary adenor na,
Fig. 13
Fig. 14
Fig. IS
Fig. I6
the tumor is located in the suprasellar cistern eccentrically and is oval in shape. The margin of the tumor is smooth and sharp. The density of the plain scan is more than 50 H and therefore higher than the pituitary adenoma (Fig. 15). The density post-enhancement increases more than 50 H, and exceeds the usual increment in pituitary adenoma (Fig. 16). In 4 cases the pre- and post-enhanced appearances are similar to the pituitary adenoma. The CT appearances
qf’q1iomu.s
Of the 6 cases, 5 are gliomas of the anterior portion of the third ventricle and one is the glioma of the optic nerve. In the histological examination, one case is astrocytoma of grade three. Three cases are astrocytomas grade two and the other two cases are grade one. In all of the 6 cases. the anterior portion of the third ventricle is abnormal. The suprasellar cistern is normal in 2 cases and abnormal in 4 cases. In 5 cases the lesion is non-homogeneous. One has several calcified spots within the tumor (Fig. 17) and the others have a large low density component mixed with a small isodense component. The other case was an isodense lesion. Before the enhancement, the margin of the lesion is not clear-cut in 5 cases and fairly clear-cut in one. After the injection of contrast media, the density of the lesion increases slightly and irregularly. In one case the lesion is oval in shape (Fig. 18) and the others are irregular in shape. The cisternography was performed in one case and demonstrates the lesion is lobulated and irregular (Fig. 19). The CT uppearance
of other lesions
One hemangioma presents as a suprasellar lobulated high dense lesion, after the injection of contrast media its density increases for 102 H, its margin is very clear-cut, just like a high density meningioma (Figs 20 and 21). In one chordoma (Figs 22 and 23) and one chondromyxoid fibroma (Figs 24 and 25), the principal changes are bone hypertrophy and destruction, the intracranial soft tissue component is comparatively small, and in the chordoma a calcified mass is seen. The postenhancement scan of the chordoma is hardly differentiated from the pituitary adenoma. An aneurysm of the anterior communicating artery presents as a round filling defect in the suprasellar cistern (Fig. 26). After injection of the contrast media, the lesion is enhanced markedly (Figs 27 and 28).
DI
Fig. 18
Fig. 17
Fig. 19
Fig. 20
Fig. 22
Fig. 21 131
Fig. 23
Fig. 25
Fig. 74
Fig. 76
CT m the diagnosis of pittmary
adenoma
133
employed, the intrasellar pituitary adenoma can be shown 17, 81. When the pituitary adenoma involves the suprasellar cistern and the diameter of its suprasellar portion is larger than 2 cm it can be demonstrated easily by the pre- and post-enhancement CT. When the suprasellar portion of the tumor is smaller than 2 cm it may be missed by plain and enhanced scan, but it can be shown clearly by cisternography. Therefore, applying CT to localize the pituitary adenoma involving suprasellar cistern is very accurate. The appearance of tumors in the sellar and parasellar region is variable. Different features can present in one kind of tumor, and the same features can present in several kinds of tumors. Some lesions which are not tumors such as suprasellar aneurysms may also present features which can be seen in the pituitary adenoma. However. every kind of tumor in the sellar and parasellar region still has some special characteristics. According to our material, 89.9’5,) of the pituitary adenomas present the aforementioned typical CT appearances, and only a small number of craniopharyngiomas, meningiomas and gliomas share these appearances. Consequently, when these appearances are demonstrated, especially when the clinical manifestations of pituitary dysfunction and the findings of intrasellar tumor on the plain film are present, the diagnosis should be pituitary adenoma growing into the suprasellar cistern. Otherwise, the craniopharyngioma, meningioma or glioma should be considered depending on the appearance of the scan. Many craniopharyngiomas present the aforementioned two kinds of typical appearances. Based on these appearances, especially the shall-like or circular calcification and relatively large dense calcification in the suprasellar cistern. and furthermore if these findings occur in the young patient, the diagnosis of craniopharyngioma can be made with confidence. When craniopharyngioma presents as a rather large low density lesion, to differentiate it from the pituitary adenoma usually is not necessary. Of course, under this situation, it is very difficult to differentiate it from other cystic lesions such as arachnoid cyst and epidermoid cyst. The appearances of many meningiomas in the sellar and parasellar region are completely identical to the pituitary adenoma and the differential diagnosis between them is very difficult. But. it is noteworthy that the density of the lesion may be helpful to the differential diagnosis. We have a group of 25 cases of meningiomas proven by operation and pathology: half of them are highly dense lesions, in 6 cases (24.0?1,,) the density is higher than the high density pituitary adenomas in our group and the CT value is above 50 H, and after injection of contrast media the density increases much more than the pituitary adenoma. When these findings are encountered. we believe that the diagnosis of meningioma should be considered first, especially when it is located eccentrically and the patient does not have endocrine disorders. The majority of gliomas present as low density areas which occupy the main part of the lesion mixed with isodensity area. Its limits are not clear-cut in the pre- and post-enhancement. After the injection of contrast media, the density of the glioma increases non-homogeneously and its contour usually is irregular. Based on these appearances, it is easy enough to differentiate it from the pituitary adenoma. However, a part of the astrocytomas of first or second grade are very similar to the pituitary adenomas (Fig. 18). Bone tumors of the sellar region. such as the chondromyxoid fibroma and chordoma in this series and the metastatic bone tumors that mainly cause bone changes would rarely be misinterpreted as pituitary adenoma. Of course, it is very difficult to distinguish between the metastatic tumors which have invaded the brain deeply and pituitary adenomas which have destroyed the bone extensively. It is also very difficult to make a correct pathological diagnosis before operation on rare tumors and other lesions in the sellar and parasellar region, such as the hemangioma in this series. and the colloid cyst of third ventricle and ectopic pinealoma, etc. that are not contained in this series [9 I I]. Some of them may present appearances similar to the pituitary adenomas. Since the advent of CT the features of the radiological examination of the cranium and brain have been greatly changed. Because CT is a non-invasive and painless method, it has been used as a screening examination for brain tumors. There have been many radiological examinations for the diagnosis and differential diagnosis of the pituitary adenoma. but how to make the proper choice is very important. In our series, the plain films and the pre- and post-enhancement scanning (except 2 cases which are sensitive to the contrast media) have been made in all cases, cisternography CT has been performed in 7 cases, cerebral angiography has been carried out in 15 cases. pneumoencephalo-
134
YIN<,-ROX
(‘HF.%
CI
graphy has been performed in 7 cases and the water soluble contrast media ventriculography has been carried out in 2 cases. After analysis, we found that most pneumoencephalography and ventriculography and some of the cerebral arteriograms are superfluous and should be excluded. For the pituitary adenoma, we deem it necessary to take the plain films first. If the diagnosis cannot he decided, or the localization has not been clear, the size. range and character are not clear, then the CT scan is performed. When the patient has endocrine disorder. the CT scan is normal and plain film is negative or equivocal. then the multidirection tomography for the sella [ 121 has to be done in order to detect the pituitary microadenoma. When CT scanning cannot determine with certainty whether the suprasellar cistern is normal or not. especially when the plain film has demonstrated an enlarged sella, then cisternography CT or pneumoencephalography with multidirectional tomography 1131 may also be performed to rule out the empty sella and to determine if the pituitary adenoma has grown up into the suprasellar cistern. Further angiography should never be done, unless the encasement of the main blood vessel requires study and the aneurysm or the tumor with rich blood supply should be ruled out.
SUMMARY The CT appearance of 85 cases of pituitary adenoma were studied and another 39 verified cases of other lesions in the sellar and parasellar region were also analyzed for comparison. The common lesions involving the sellar and parasellar region are pituitary adenoma, craniopharyngioma, meningioma and glioma; among them the pituitary adenoma encompasses about 70’!,,. The appearances of lesions in the sellar and parasellar region are variable, different features can present in one kind of lesion and the same appearance can present in several kinds of lesions. However, each kind of the common lesions in this region still has some special identifying characteristics. In this series, 89.9O,, of the pituitary adenomas growing into the suprasellar cistern present typical signs. A filling defect in the suprasellar cistern or obliteration of this cistern are very common. The density of the lesion is the same as or a little bit higher than the normal brain. The cystic change area is not often present or is comparatively small. After injection of contrast media its density increases to 25.3 H on average and the increment is usually less than 80”,,. It is usually 2~-4 cm in diameter and round or oval in shape. Many craniopharyngiomas present as a low density lesion with shell-like calcification or relatively large calcified mass in the suprasellar cistern. It is hard to misinterpret them as a pituitary adenoma, especially in the young patient. The density of most meningiomas in the pre- and post-enhancement scan is much higher than the high density pituitary adenoma. This may be helpful to differentiate the meningioma from the pituitary adenoma. The majority of gliomas in the pre- and post-enhancement scan present as non-homogenous lesions with large low density areas and irregular and undefined margins. Based on these appearances, it is easy enough to differentiate it from the pituitary adenoma. However, it is worthy of notice that some of the common lesions and many of the rare lesions in the sellar and parasellar region may present an appearance similar to pituitary adenoma. Our policy about how to choose the procedures for the diagnosis of the pituitary adenoma is discussed. REFERENCES I. C. M. Citrin and D. 0. Davis. Computerized tomography in the evaluation of pituitary adenoma. Inres~. Rad. I, 27 35 (1977). 2. D. F. Danoff, S. Pripstein, N. Grace, S. Kramer and K. F. Lee, The value of computerized tomography in delineatmg suprasellar extension of pituitary adnoma for radiotherapeutic mangement. Cancer 42, 10661072 (1978). 3. C. Glydensted and A. Karle, Computed tomography of intra and juxtasellar lesions, 14, 5 13 (1977). 4. T. P. Naidich. T. P. R. S. Pinto, M. J. Kushner. J. P. Lin, 1. I. Kricheff. N. E. Leeds and N. E. Chase, Evaluatton of sellar and parasellar masses by computed tomography, Radiology 120, 91-99 (1976). 5. S. M. Wolpert, K. D. Post, B. J. Biller and M. E. Molitch, The value of computed tomography in evaluating patients with prolactinoma, Rudioloyy 131, 117-119 (1979). 6. A. Hatem. M. Bergstrom and T. Greitz, Diagnosis of sellar and parasellar lesions by computed tomography, Nwrorudiology 18, 2499258 (1979). 7. A. Syvertsen. V. M. Haughton, A. L. Williams and J. F. Cusick. The computed tomographic appearance of the normal pituitary gland and pituitary microadfenoma. Rudiolog~ 133, 385 391 (1979).
CT in the diagnosis
of pttuitary
I35
adenoma
8. I. 1. Kricheff, The radiology diagnosis of pituitary adenoma. Rrrdioloy~~ 131, 263 265. 1979. 9. N. E. Leeds and T. P. Naidich. Computerized tomography in the diagnosis of scllar and parasellar lessons. Scwin Romry. 12. 1’1-135 (1977). IO. D. I. Sung. L. Harisiadis and C. H. Chang. mtdline pineal tumors and suprasellar germinomas: high]) curable by irradiation. Rudioloy~ 128, 7455751 (1978). 1 I. A. B. Dublm A. B. and J. R. Youmans. Computer assisted ventriculography. J. Comput. trssi.sr. Tomogr. 2, 162 164 (1978). 13. W. D. Robertson and T. H. Newton. Radiologic assessment of pituitary microadenoma. .4rn. J. Rocwlgq. 131. 4X9 492 (1978). 13. J. C. Johnson, M. Lubow and J. Steam. Polytomoencephalographic of the optic chiasm and adjacent structures. Rtrdio/og~~ 114, 629-634 (1975). About the Author-TIAN-ZHEN SHEN M.D.. female, 41-yr old, graduated from College in 1963. Now, she is the attending doctor in Department of Radiology Shanghai First Medical College, Shanghai, China.
Shanghai of Hua
First Medical Shan Hospital.
CHEN M.D., male, 48-yr old, graduated from Shanghai First Medical College in 1955. Now, he is the chief of Department of Neurosurgery of Hua Shan Hospital, Shanghai First Medical College. Shanghai, China.
About the AuthorpGONG-BAI
the Author SHEN-SHENG TANG M.D.. male, 43-yr old, graduated from College in 1959. Now, he is the attending doctor in Department of Neurosurgery Shanghai First Medical College. Shanghai. China.
About
Shanghai First Medical of Hua Shan Hospital,
CHEN M.D.. 50-yr old. graduated from Shanghai First Medical College in 1956. Presently Chief. Department of Radiology, Hua Shan Hospital. after serving as Visiting Professor of Radiology at Downstate Medical Center. State University of New York during 198&1981. Member of the Chinese Radiological Society, Commissioner of the Cllimw Jowt~ol of’Radioloy,. Associate Editor of the R~fw~wu of rho Fowiyn Medicine. Radiological Fascicle. About the Author-XING-RONG