- Email: [email protected]
Magnetic resonance imaging in hydatid disease
Clinical Radiology (1987) 38, 141-144
Magnetic Resonance Imaging in Hydatid Disease D. L. MORRIS, J. BUCKLEY, R. GREGSON and B. S. W O R T H I N G T O N
Departments of Surgery and Radiology, University Hospital, Nottingham
Magnetic resonance imaging was evaluated in 12 patients with hydatid disease (Echinococcus granulosus). Patients also underwent real time ultrasound and computed tomography imaging. Clear images of hepatic hydatid cysts were produced by magnetic resonance imaging, and intracyst structures were demonstrated. Changes in the appearance of cysts were seen following chemotherapy. Whilst not cost effective at present, if further improvements allow differentiation of simple (epithelial) and hydatid cysts or viable and dead hydatid cysts this technique could be of clinical value.
The spin sequence utilised for the magnetic resonance images was a TR 500 TE 40 spin echo sequence giving relatively T1 weighted images, the advantages of this sequence being a relatively high signal to noise ratio and good contrast between solid and fluid contents within a cyst. The three imaging modalities were performed or supervised by radiologists experienced in these respective fields independently and without consultation. RESULTS
While hydatid disease is relatively uncommon in the UK (Stallbaumer et al., 1983), it is still an extremely important world health problem (Matossian et al., 1977). The ultrasound and computed tomography appearances of hydatid disease due to Echinococcus granulosus are well established (Alltree, 1979; Niron and Ozer, 1981; Beggs, 1983). Both modalities are useful and often allow a definite diagnosis on the basis of the characteristic appearance of daughter cysts and other intracyst debris. The advent of chemotherapy for hydatid disease (Schantz et al., 1982; Morris et al., 1985) has provided the need for repeated radiological monitoring during therapy to assess response and both computed tomography and ultrasound have been used (Morris et al., 1984; Singcharoen et al., 1985). While radiation exposure during computed tomography is small, clearly it would be better to avoid repeated exposure in assessing response in young patients with this benign disease. METHOD
Twelve patients with hydatid disease were imaged by computed tomography, real time ultrasound and magnetic resonance imaging. Three patients were also re-examined following treatment with albendazole (Zentel, Smith, Kline and French) 10mg/kg for 1 month. The site of the cysts is shown in Table 1. All the cysts were proved histologically to be E. granulosus. The ultrasound examinations were performed on IGE Datason and Philips SDU 3000 machines and the computed tomography using a Picker 1200 SX 4th generation machine. Patients were scanned 20min after the oral administration of 3 % sodium meglumine diatrizoate (Gastrografin, Schering) solution to outline the upper gastro-intestinal tract and slices throughout the liver were obtained at 15 to 20min intervals. During the procedure, an intravenous infusion of 100 ml of iopamidol (Niopam 300, Merck) was administered. The instrument used was a Picker 0.15 Tesla resistive unit and a body coil was employed for examinations. Respiratory gating was not available.
Our initial experience with patients 1 and 2 using magnetic resonance was unsatisfactory and, whilst a hepatic abnormality was demonstrated with this method, it was far from clear. The next two patients were kindly imaged with magnetic resonance for us at the Hammersmith Hospital. In these and the remaining eight patients examined in Nottingham good images were obtained. Some difficulty was experienced in patient 7 due to the patient's bony deformity (fixed hip flexion due to involvement of the left hip joint by hydatid disease). However, the abnormal bone was clearly demonstrated in this case. Daughter cysts were demonstrated in seven of the nine patients in whom they were detected by ultrasound or computed tomography. The unsatisfactory scans at the beginning of the series accounted for the remaining two. Examples of computed tomography and magnetic resonance images from patient 5 are given (Fig. 1). It will be seen that the characteristic appearance of the daughter cysts within the main cyst cavity are seen on the magnetic resonance image with exceptional clarity. Figs 2a and 2b shows a hepatic cyst in another patient which is thick walled and lying in the left lobe of the liver. This was subsequently confirmed at operation. A comparative computed tomography scan (Fig. 2c) is no clearer than the magnetic resonance image. The final magnetic resonance illustration (Fig. 2d) shows a thick walled cyst in the left upper quadrant of the abdomen. Complex cysts were also imaged successfully. In patient 4 an irregular cavity communicating with the biliary tree was identified. Magnetic resonance imaging, whilst clearly identifying the cyst, did not show any specific feature in those hydatid cysts without characteristic intracyst debris (daughter cysts) that would allow their differentiation from simple hepatic cysts. Changes in the appearances of cysts during chemotherapy were seen in the three patients who were rescanned. Patient 5 (KG) had a repeat magnetic resonance examination after an interval of 4 weeks. The first demonstrated a large, well-defined, multiloculated cyst in the right lobe of the liver while the repeat showed no change in the size of the cyst. There was an increase in complexity with a greater number of intracystic septae and a slight
142
CLINICAL RADIOLOGY
Table 1 - Comparison of 3 scanning modalities in hydatid disease Patient
Site
1. EP 2. PW 3. TM 4. MM 5. KG 6. PG 7. MP 8. HT 9. GB 10. MG 11. YM 12. RR
Liver/femur Liver Liver Liver Liver Liver Bone (pelvis) Liver Liver Liver Spleen/peritoneum Liver
Computed tomography
Ultrasound
Magnetic resonance imaging
DC DC Complex cavity DC No DC Clearly defined DC Thick walled DC Thick walled DC
DC DC DC 0 DC No DC 0 DC DC DC DC DC
Not clear Not clear DC Complex.cavity DC No DC Abnormal bone structure DC DC DC DC DC
DC Daughter cyst seen.
lesion postero-laterally. Patient 12 (RR) was found at presentation to have a large cyst with multiple daughter cysts and a considerable amount of intracystic solid material in the right lobe of the liver. The second examination 4 weeks later demonstrated an increase in the size of the cyst. Multiple daughter cysts remained
increase in the solid components within the cyst. Patient 10 (MG) had a large multiloculated cyst at the inferior margin of the right lobe of the liver with a smaller cyst present antero-lateral to the right psoas muscle. The second examination 5 weeks later demonstrated an increase in the solid component of the
(b) (a)
(e) Fig. 1 - (a) Patient 5. Computed tomography scan showing a hydatid cyst containing multiple daughter cysts, in the right lobe of the liver. (b) Magnetic resonance image. Transverse section showing the large hepatic cyst with clear visualisation of daughter cysts within. (c) Magnetic resonance image. Longitudinal section, showing the relationship of the cyst to the remaining liver tissue and the diaphragm.
143
M A G N E T I C R E S O N A N C E I M A G I N G IN H Y D A T I D D I S E A S E
(a)
(b)
(c)
(d)
Fig 2. - (a) Patient 9. Magnetic resonance image of hydatid cyst in the left lobe of the liver. (b) Magnetic resonance image. Close up of cyst clearly showing a thick fibrous wall. (c) Computed tomography showing the thick walled cavity in the left lobe. (d) Magnetic resonance image of the thick walled left upper abdominal cyst lying posterior to the stomach and anterior to the kidney. and these had also increased in size. There was a more marked increase in the amount of solid material within the cyst.
DISCUSSION Magnetic resonance examination produces images of exceptional structural clarity but avoids repeated radiation exposure. It is capable of detecting changes in appearance of hydatid cysts during chemotherapy. At present, we could not advocate its widespread use because of cost and this is likely to remain a problem. Ultrasound thus remains the most cost effective means of imaging hepatic hydatid disease. We feel that computed t o m o g r a p h y is however most useful in providing structural information for the surgeon (road map) and perhaps magnetic resonance imaging could replace it in this role. Magnetic resonance imaging offers the advantage of multi-planar imaging and bowel gas does not reduce image quality as it does with ultrasound. Its m a j o r disadvantage remains the relatively long imaging time, with consequent artefact due to respiratory move-
ment, which is largely overcome if respiratory gating is employed. This was not available during this study and, thus, an i m p r o v e m e n t in picture quality is to be expected when it is employed. It achieves superior soft tissue contrast in comparison with c o m p u t e d tomography and we believe that with further refinement it may well be able to differentiate between simple (epithelial) hepatic cysts and those due to Echinococcus. This would be of some importance because, whilst aspiration m a y be therapeutic for simple cysts, anaphylaxis and peritoneal dissemination are real risks of aspirating hydatid cysts. The changes seen on magnetic resonance imaging also provide encouragement for the belief that in the future we m a y be able to differentiate viable and dead cysts, again with considerable clinical benefit. Acknowledgements. We are most grateful to the NMR unit at the Hammersmith Hospital, London, for imaging patients 3 and 4.
REFERENCES
Alltree, M (1979). Scanning in hydatid disease. Clinical Radiology, 30, 691-697.
144
CLINICAL RADIOLOGY
Beggs, I (1983). The radiological appearances of hydatid disease of the liver. Clinical Radiology, 34, 555-563. Matossian, RM, Rukord, MD & Smyth, JD (1977). Hydatidosis - a global problem of increasing importance. WHO Chronicle, 55, 499-507. Morris, DL Skeene-Smith, H, Hayes, A & Burrows, FEO (1984) Abdominal hydatid disease - computed tomography and ultrasound changes during albendazole therapy. Clinical Radiology, 35, 297-300. Morris, DL, Dykes, PW, Marriner, S, et al. (1985). Albendazoleobjective evidence of response in human hydatid disease. Journal of the American Medical Association, 253, 2053-2057.
Niron, E A & Ozer, H (1981). Ultrasound appearances of liver hydatid disease. British Journal of Radiology, 54, 335-338. Schantz, PM, Van den Bossche, H & Eckert, J (1982). Chemotherapy for larval Echinoccoccus in animals and humans - Report of a workshop. Zentbal. ParasitenKunde, 67, 5-26. Singcharoen, T, Mahanonda~ N, Powell, LW & Baddeley, H (1985). Sonographic changes of hydatid cyst of the liver after treatment with mebendazole and albendazole. British Journal of Radiology, 58, 905-907. Stallbaumer, MF, Clarkson, M J, Pritchard, F, Borley, KW & Morris, DL (1983) Serological diagnosis and current epidemiology of hydatid disease in England and Wales. Gut, 24, A996.
Magnetic Resonance Imaging in Hydatid Disease D. L. MORRIS, J. BUCKLEY, R. GREGSON and B. S. W O R T H I N G T O N
Departments of Surgery and Radiology, University Hospital, Nottingham
Magnetic resonance imaging was evaluated in 12 patients with hydatid disease (Echinococcus granulosus). Patients also underwent real time ultrasound and computed tomography imaging. Clear images of hepatic hydatid cysts were produced by magnetic resonance imaging, and intracyst structures were demonstrated. Changes in the appearance of cysts were seen following chemotherapy. Whilst not cost effective at present, if further improvements allow differentiation of simple (epithelial) and hydatid cysts or viable and dead hydatid cysts this technique could be of clinical value.
The spin sequence utilised for the magnetic resonance images was a TR 500 TE 40 spin echo sequence giving relatively T1 weighted images, the advantages of this sequence being a relatively high signal to noise ratio and good contrast between solid and fluid contents within a cyst. The three imaging modalities were performed or supervised by radiologists experienced in these respective fields independently and without consultation. RESULTS
While hydatid disease is relatively uncommon in the UK (Stallbaumer et al., 1983), it is still an extremely important world health problem (Matossian et al., 1977). The ultrasound and computed tomography appearances of hydatid disease due to Echinococcus granulosus are well established (Alltree, 1979; Niron and Ozer, 1981; Beggs, 1983). Both modalities are useful and often allow a definite diagnosis on the basis of the characteristic appearance of daughter cysts and other intracyst debris. The advent of chemotherapy for hydatid disease (Schantz et al., 1982; Morris et al., 1985) has provided the need for repeated radiological monitoring during therapy to assess response and both computed tomography and ultrasound have been used (Morris et al., 1984; Singcharoen et al., 1985). While radiation exposure during computed tomography is small, clearly it would be better to avoid repeated exposure in assessing response in young patients with this benign disease. METHOD
Twelve patients with hydatid disease were imaged by computed tomography, real time ultrasound and magnetic resonance imaging. Three patients were also re-examined following treatment with albendazole (Zentel, Smith, Kline and French) 10mg/kg for 1 month. The site of the cysts is shown in Table 1. All the cysts were proved histologically to be E. granulosus. The ultrasound examinations were performed on IGE Datason and Philips SDU 3000 machines and the computed tomography using a Picker 1200 SX 4th generation machine. Patients were scanned 20min after the oral administration of 3 % sodium meglumine diatrizoate (Gastrografin, Schering) solution to outline the upper gastro-intestinal tract and slices throughout the liver were obtained at 15 to 20min intervals. During the procedure, an intravenous infusion of 100 ml of iopamidol (Niopam 300, Merck) was administered. The instrument used was a Picker 0.15 Tesla resistive unit and a body coil was employed for examinations. Respiratory gating was not available.
Our initial experience with patients 1 and 2 using magnetic resonance was unsatisfactory and, whilst a hepatic abnormality was demonstrated with this method, it was far from clear. The next two patients were kindly imaged with magnetic resonance for us at the Hammersmith Hospital. In these and the remaining eight patients examined in Nottingham good images were obtained. Some difficulty was experienced in patient 7 due to the patient's bony deformity (fixed hip flexion due to involvement of the left hip joint by hydatid disease). However, the abnormal bone was clearly demonstrated in this case. Daughter cysts were demonstrated in seven of the nine patients in whom they were detected by ultrasound or computed tomography. The unsatisfactory scans at the beginning of the series accounted for the remaining two. Examples of computed tomography and magnetic resonance images from patient 5 are given (Fig. 1). It will be seen that the characteristic appearance of the daughter cysts within the main cyst cavity are seen on the magnetic resonance image with exceptional clarity. Figs 2a and 2b shows a hepatic cyst in another patient which is thick walled and lying in the left lobe of the liver. This was subsequently confirmed at operation. A comparative computed tomography scan (Fig. 2c) is no clearer than the magnetic resonance image. The final magnetic resonance illustration (Fig. 2d) shows a thick walled cyst in the left upper quadrant of the abdomen. Complex cysts were also imaged successfully. In patient 4 an irregular cavity communicating with the biliary tree was identified. Magnetic resonance imaging, whilst clearly identifying the cyst, did not show any specific feature in those hydatid cysts without characteristic intracyst debris (daughter cysts) that would allow their differentiation from simple hepatic cysts. Changes in the appearances of cysts during chemotherapy were seen in the three patients who were rescanned. Patient 5 (KG) had a repeat magnetic resonance examination after an interval of 4 weeks. The first demonstrated a large, well-defined, multiloculated cyst in the right lobe of the liver while the repeat showed no change in the size of the cyst. There was an increase in complexity with a greater number of intracystic septae and a slight
142
CLINICAL RADIOLOGY
Table 1 - Comparison of 3 scanning modalities in hydatid disease Patient
Site
1. EP 2. PW 3. TM 4. MM 5. KG 6. PG 7. MP 8. HT 9. GB 10. MG 11. YM 12. RR
Liver/femur Liver Liver Liver Liver Liver Bone (pelvis) Liver Liver Liver Spleen/peritoneum Liver
Computed tomography
Ultrasound
Magnetic resonance imaging
DC DC Complex cavity DC No DC Clearly defined DC Thick walled DC Thick walled DC
DC DC DC 0 DC No DC 0 DC DC DC DC DC
Not clear Not clear DC Complex.cavity DC No DC Abnormal bone structure DC DC DC DC DC
DC Daughter cyst seen.
lesion postero-laterally. Patient 12 (RR) was found at presentation to have a large cyst with multiple daughter cysts and a considerable amount of intracystic solid material in the right lobe of the liver. The second examination 4 weeks later demonstrated an increase in the size of the cyst. Multiple daughter cysts remained
increase in the solid components within the cyst. Patient 10 (MG) had a large multiloculated cyst at the inferior margin of the right lobe of the liver with a smaller cyst present antero-lateral to the right psoas muscle. The second examination 5 weeks later demonstrated an increase in the solid component of the
(b) (a)
(e) Fig. 1 - (a) Patient 5. Computed tomography scan showing a hydatid cyst containing multiple daughter cysts, in the right lobe of the liver. (b) Magnetic resonance image. Transverse section showing the large hepatic cyst with clear visualisation of daughter cysts within. (c) Magnetic resonance image. Longitudinal section, showing the relationship of the cyst to the remaining liver tissue and the diaphragm.
143
M A G N E T I C R E S O N A N C E I M A G I N G IN H Y D A T I D D I S E A S E
(a)
(b)
(c)
(d)
Fig 2. - (a) Patient 9. Magnetic resonance image of hydatid cyst in the left lobe of the liver. (b) Magnetic resonance image. Close up of cyst clearly showing a thick fibrous wall. (c) Computed tomography showing the thick walled cavity in the left lobe. (d) Magnetic resonance image of the thick walled left upper abdominal cyst lying posterior to the stomach and anterior to the kidney. and these had also increased in size. There was a more marked increase in the amount of solid material within the cyst.
DISCUSSION Magnetic resonance examination produces images of exceptional structural clarity but avoids repeated radiation exposure. It is capable of detecting changes in appearance of hydatid cysts during chemotherapy. At present, we could not advocate its widespread use because of cost and this is likely to remain a problem. Ultrasound thus remains the most cost effective means of imaging hepatic hydatid disease. We feel that computed t o m o g r a p h y is however most useful in providing structural information for the surgeon (road map) and perhaps magnetic resonance imaging could replace it in this role. Magnetic resonance imaging offers the advantage of multi-planar imaging and bowel gas does not reduce image quality as it does with ultrasound. Its m a j o r disadvantage remains the relatively long imaging time, with consequent artefact due to respiratory move-
ment, which is largely overcome if respiratory gating is employed. This was not available during this study and, thus, an i m p r o v e m e n t in picture quality is to be expected when it is employed. It achieves superior soft tissue contrast in comparison with c o m p u t e d tomography and we believe that with further refinement it may well be able to differentiate between simple (epithelial) hepatic cysts and those due to Echinococcus. This would be of some importance because, whilst aspiration m a y be therapeutic for simple cysts, anaphylaxis and peritoneal dissemination are real risks of aspirating hydatid cysts. The changes seen on magnetic resonance imaging also provide encouragement for the belief that in the future we m a y be able to differentiate viable and dead cysts, again with considerable clinical benefit. Acknowledgements. We are most grateful to the NMR unit at the Hammersmith Hospital, London, for imaging patients 3 and 4.
REFERENCES
Alltree, M (1979). Scanning in hydatid disease. Clinical Radiology, 30, 691-697.
144
CLINICAL RADIOLOGY
Beggs, I (1983). The radiological appearances of hydatid disease of the liver. Clinical Radiology, 34, 555-563. Matossian, RM, Rukord, MD & Smyth, JD (1977). Hydatidosis - a global problem of increasing importance. WHO Chronicle, 55, 499-507. Morris, DL Skeene-Smith, H, Hayes, A & Burrows, FEO (1984) Abdominal hydatid disease - computed tomography and ultrasound changes during albendazole therapy. Clinical Radiology, 35, 297-300. Morris, DL, Dykes, PW, Marriner, S, et al. (1985). Albendazoleobjective evidence of response in human hydatid disease. Journal of the American Medical Association, 253, 2053-2057.
Niron, E A & Ozer, H (1981). Ultrasound appearances of liver hydatid disease. British Journal of Radiology, 54, 335-338. Schantz, PM, Van den Bossche, H & Eckert, J (1982). Chemotherapy for larval Echinoccoccus in animals and humans - Report of a workshop. Zentbal. ParasitenKunde, 67, 5-26. Singcharoen, T, Mahanonda~ N, Powell, LW & Baddeley, H (1985). Sonographic changes of hydatid cyst of the liver after treatment with mebendazole and albendazole. British Journal of Radiology, 58, 905-907. Stallbaumer, MF, Clarkson, M J, Pritchard, F, Borley, KW & Morris, DL (1983) Serological diagnosis and current epidemiology of hydatid disease in England and Wales. Gut, 24, A996.