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MR features of gastrointestinal stromal tumors
Journal of Clinical Imaging 29 (2005) 251 – 254
MR features of gastrointestinal stromal tumors T. Caramellaa,T, S. Schmidta, P. Chevalliera, M. Saint Paulb, J.L. Bernardc, R. Bidolid, J.N. Brunetona a
Department of Radiology, Centre Hospitalier Re´gional et Universitaire de Nice, Hoˆpital Archet II, 151 route de Saint-Antoine de Ginestie`re, BP 3079, Nice 06202, France b Department of Anatomopathology, Centre Hospitalier Re´gional et Universitaire de Nice, Hoˆpital Archet II, 151 route de Saint-Antoine de Ginestie`re, BP 3079, Nice 06202, France c Department of Abdominal Surgery, Centre Hospitalier Re´gional et Universitaire de Nice, Hoˆpital Archet II, 151 route de Saint-Antoine de Ginestie`re, BP 3079, Nice 06202, France d Department of Hepatogastroenterology, Centre Hospitalier Re´gional et Universitaire de Nice, Hoˆpital Archet II, 151 route de Saint-Antoine de Ginestie`re, BP 3079, Nice 06202, France Received 29 September 2004
Abstract We report on two patients presenting with gastrointestinal stromal tumors (GIST). The important tumor size and the marked tissular hypersignal seen on T2-weighted magnetic resonance images (MRI) should be considered as magnetic resonance (MR) features strongly indicating diagnosis of GIST. D 2005 Elsevier Inc. All rights reserved. Keywords: Gastrointestinal stromal tumor (GIST); Gastrointestinal tract, MR; Gastrointestinal system, neoplasm
1. Introduction
2. Case 1
Gastrointestinal stromal tumors (GIST) are rare digestive neoplasms originating from the cells of Cajal, a complex cell network located within the bowel wall with pacemaker function. The detection of specific immunological markers has recently led to the revision of their histopathological classification [1]. They are presently defined as stromal tumors, including spindle-shaped and epithelial cells with the expression of the KIT protein (CD 117) while being of uncertain evolution [2]. We report on two cases of GISTs investigated by magnetic resonance imaging (MRI) in our department.
A 72-year-old woman was investigated for incidentally detected important hepatomegaly (Fig. 1). Ultrasonography and computed tomography (CT) had shown a hypoechogenic and hypodense mass without contrast enhancement, respectively, being in continuity with the left liver lobe without any clear demarcation from the latter. Gastroendoscopy revealed extrinsic gastric compression without intraluminal tumor; however, air insufflation was difficult and restricted. Complementary MRI was performed (Gyroscan NT10 1 T, Philipps Medical Systems, Best, The Netherlands) with fat suppressed T2-weighted spin-echo sequences (spectral presaturation with inversion recovery SPIR/TSE: TE = 80 ms, TR = 1800 ms), followed by T1-weighted gradient-echo sequences (BH: TE = 4.5 ms, TR =118 ms) before and after the intravenous injection of gadolinium at a dose of 0.2 ml/kg (Dotarem 0.5 mmol/ml; Guerbet, Roissy CdG, France).
T Corresponding author. E-mail address: [email protected] (T. Caramella). 0899-7071/05/$ – see front matter D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.clinimag.2004.12.001
252
T. Caramella et al. / Journal of Clinical Imaging 29 (2005) 251–254
on SPIR sequences relative to liver parenchyma. One could distinguish two internal components, a fibrous central hyposignal seen on T1-weighted images without enhancement, even on delayed phase after intravenous contrast medium injection, and a contrast-enhanced tissular rim. Starting in the arterial phase, enhancement was increasing towards the center during the portal phase. Tumor extension to the gastric antrum was observed measuring 25 mm in its largest diameter, indicating its gastric origin (dumbbell tumor). Four ultrasound-guided percutaneous biopsies were performed, using an automatic coaxial 14 G needle of 10-cm length (Barde, Covington, USA). Macroscopically tumor cells appeared epitheloid; immunostaining revealed the expression of KIT protein. After surgical resection, histology was confirmed. No postoperative complication occurred; no adjunct therapy was performed. Repeated MRI after 6 months did not show any tumor recurrence.
3. Case 2 An 84-year-old-woman presented with a recently appeared abdominal mass. Initial ultrasonography revealed a heterogeneous prepancreatic tumor with large central necrosis and trabecular pattern (Fig. 2). Using the same sequences as in the first patient, MRI revealed a large intraperitoneal tumor of 14 cm, strongly hyperintense on T2-weighted images. T1-weighted images after intravenous Gadolinium injection allowed the distinction of two components of this hypersignal: a central necrosis and a hypervascularized tissular rim. The strong relationship of the tumor with the stomach displaced posterioly strongly suggested gastric origin without definitive proof, however, because there was no intraluminal growth. Neither coronal nor sagittal plane could establish diagnosis. Ultrasound-guided biopsy was equally performed using the same technique as described above. Histopathology revealed a large necrotic tumor composed of spindle-shaped cells, with a strong expression of CD117 marker without mitosis.
4. Discussion Fig. 1. Case 1. (A) T2 axial SPIR: homogeneous hypersignal relative to liver parenchyma. Tumor extension to the gastric antrum is well visible (*). (B and C) T1 axial after gadolinium injection arterial and veinous phase. Two internal components: a fibrous central hyposignal without enhancement and a contrast-enhanced tissular rim.
MRI revealed a large tumor of 221130 cm extending from left subphrenic space to the middle abdomen, characterized by a strong homogeneous hypersignal seen
GISTs are rare stromal tumors representing 3.6% of gastric tumors [1]. Accounting for 5% of all gastrointestinal sarcomas, they are observed in men and women equally at a mean age of 60 years, rarely below 40 years. Seventy percent of GISTs arise from the stomach, 20% from the small bowel, and 10% from another origin (colon, rectum, and esophagus). They are mostly incidentally discovered despite an initial tumor size varying between 1 and 20 cm because there are
T. Caramella et al. / Journal of Clinical Imaging 29 (2005) 251–254
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Fig. 2. Case 2. (A) Ultrasound: heterogeneous tumor with large central necrosis and trabecular pattern. (B) T2 coronal view. Large intraperitoneal tumor strongly hyperintense. (C and D) T1 axial without and after gadolinium injection. Two internal components: a central necrosis and a hypervascularized tissular rim.
no or little specific clinical symptoms. Even large GISTs do not typically cause compression or occlusion. These tumors have rarely been described on MRI [3–7]. A recent revision of their anatomopathological classification based on immunoreactivity for KIT suggests that some of these lesions have been incorrectly identified up to now. The important tumor size at detection can conceal their exact origin. Neither endoscopy nor ultrasound in both of our cases, neither CT in one of them could clearly determine the gastric origin. MRI was able to confirm this origin in one case by visualization of intraluminal exophytic tumor growth and to indicate it strongly in the second case. The multiplanar imaging modalities of MRI might also be useful in difficult cases. Furthermore, these tumors mostly have a double morphology, i.e., a necrotic (sometimes hemorrhaged) and tissular component, both characterized as strong hypersignal on T2-weighted images relative to liver parenchyma [6,7], proven by our observations. According to our two cases, this T2-weighted hypersignal is remarkably intense: Soft tissue components showed similar hyperintensity on T2-weighted MR images as that
of cerebrospinal fluid and were difficult to distinguish from central necrosis, even being fluid. T1-weighted hypointense solid components of the tumor strongly enhanced after the intravenous Gadolinium injection seen on delayed phase images best and reflecting hypervascularization, as described on CT already [8]. In our two patients, tissular components were predominantly peripheral. The center was fibrous in the first, and necrotic in the second case. This central fibrosis has not yet been reported, according to our knowledge. In the second case, there were also focal hyperintensities on T1-weighted nonenhanced MR images, representing hemorrhage as it has already been described several times [6].
5. Differential diagnosis The most difficult differential diagnosis on MRI includes all the other mesenchymal neoplasms (leiomyomas, leiomyosarcomas, schwannomas, schwannosarcomas, neurofibromas, and neuroendocrine tumors), being the more difficult because little has been known about.
254
T. Caramella et al. / Journal of Clinical Imaging 29 (2005) 251–254
Gastric schwannoma [9] show slight hyperintensity on T1-weighted and moderately to strongly hypersignal on T2-weighted MR images. After the intravenous injection of Gadolinium, slow but homogeneous contrast enhancement is observed. Leiomyomas have mostly been described as masses arising from the uterus [10] with a low signal intensity on T2-weighted MR images and an isosignal relative to the myometrium on T1-weighted MR images enhancing strongly after intravenous Gadolinium injection. Gastric leiomyoma [11] may demonstrate central T2-weigted hyperintensity due to pseudocystic transformation. There might also be a horizontal hypointense level seen on T1- and T2-weighted MR images resulting from former hemorrhage. The size of these two benign tumors, gastric schwannoma and leiomyoma, is mostly small, which is inferior to 5 cm. Leiomyosarcoma demonstrates central necrosis with focal parietal contrast enhancement. For sure, this is the tumor with the most similar MR characteristics to GISTs. In case of tumor dissemination, radiological appearance of secondary liver lesions may help because liver metastases due to leiomyosarcoma are hypervascularized, therefore best seen on early phase after intravenous contrast enhancement. Epidemiologically, leimoyomas, leiomyosarcomas, and schwannomas exceptionnally arise from the stomach, in any case, far less often than GISTs. All these tumors are hypervascularized lesions on CT [8]. The other differential diagnoses include large solid abdominal masses. Adenocarcinomas only rarely demonstrate exophytic growth [6], but more often cause hemorrhage and luminal stenosis; therefore, symptoms appear at an earlier stage as with GISTs. Because adenocarcinomas are known for primarily lymphatic dissemination, epigastric and pericoeliac lymph node metastases rapidly occur, which is not typically seen with GISTs metastasizing in lymph nodes exceptionally only. Desmoid tumors are rare and benign, but frequently recurrent tumors, isolated or associated with Gardener syndrome. The main localization is the mesentery. Classic MRI features are hypointensity on T1- and T2-weighted sequences. There might also be a moderate hypersignal on T2-weighted MR images; contrast enhancement has never been reported after intravenous Gadolinium injection [12]. Histological diagnosis of GISTs can easily be obtained by imaging guided biopsy. Several authors report on the complications after biopsy because of skin metastases found along the needle path [13]. Therefore, we recommend a sheath of protection by using a coaxial system, allowing for multiple core biopsy while avoiding skin contamination. Ideally, you might mark the point of incision on the skin for later excision during surgical intervention. The potential curative treatment of GIST is complete surgical resection. Prognosis is serious, with mean survival of 20 months in case of tumor dissemination [1].
Recently, a new molecule, Imatinib (Glivec, Novartis, Switzerland), a specific KIT-receptor inhibitor, has increasingly been used for the chemotherapy of GIST. Although published on a limited series only, first results are very promising. The main indication is, at present, primarily metastasizing tumors, but it might also be used for adjuvant or neoadjuvant treatment in the future [1].
6. Conclusion Based on tumor features of localization, volume, and signal intensity, the diagnosis of GIST can be advocated on MRI.
References [1] Connolly EM, Gaffney E, Reynolds JV. Gastrointestinal stromal tumours. Br J Surg 2003;90:1178 – 86. [2] Petitjean B, Beaulieu S, Loubouti-Sanchez A, Bergue A. Tumeurs stromales digestives: Anatomopathologie, diagnostic et traitement. Encycl Me´d Chir (Editions Scientifiques Me´dicales Elsevier SAS, Paris), Gastro-enterologie, 9-027-A-15, 2003 [6 pp]. [3] Hasegawa S, Semelka RC, Noone TC, Woosley JT, Marcos HB, Kenney PJ, Siegelman ES. Gastric stromal sarcomas: correlation of MR imaging and histopathologic findings in nine patients. Radiology 1998;208:591 – 5. [4] Naitoh I, Okayama Y, Masaaki H, Kitajima Y, Hayashi K, Okamoto T, Akita S, Gotoh K, Mizusima M, Sano H, Ohara H, Nomura T, Joh T, Yokoyama Y, Itoh M. Exophytic pedunculated gastrointestinal stromal tumor with remarkable cystic change. J Gastroenterol 2003;38: 1181 – 4. [5] Mignon F, Julie C, Izzillo R, Luciani A, Guichoux F, Mesurolle B, El Hajam M, Qanadli SD, Chagnon S, Lacombe P. Imaging features of gastric stromal tumors: radiologic–pathologic correlation. Report of 4 cases. J Radiol 2000;81:875 – 81. [6] Levy AD, Remotti HE, Thompson WM, Sobin LH, Miettinen M. Gastrointestinal stromal tumors: radiologic features with pathologic correlation. Radiographics 2003;23:283 – 304. [7] Jost D, Stroszczynski C, Chmelik P, Gaffke G, Schlecht I, Pink D, Reichart P, Schneider U, Hohenberger P, Felix R. Morphologie gastrointestinaler Stromatumoren im fortgeschrittenen Stadium der Erkrankung: Ausgangsbefunde vor Chemotherapie mit Imatinib. Fortschr Rfntgenstr 2003;175:791 – 8. [8] Ghanen N, Altehoefer C, Furtwangler A, Winterer J, Schafer O, Springer O, Kotter E, Langer M. Computed tomography in gastrointestinal stromal tumors. Eur Radiol 2003;13:1669 – 78. [9] Karabulut N, Martin DR, Yang M. Case report: gastric schwannoma: MRI findings. Br J Radiol 2002;75:624 – 6. [10] Szklaruk J, Tamm EP, Haesun C, Varavithya V. MR Imaging of common and uncommon large pelvic masses. Radiographics 2003;23: 403 – 24. [11] Marcy PY, Franc¸ois E, Bruneton JN, Peroux JL, Balu-Maestro C, Melia P, Dubruque F, Aviotti-Gasperoni A. Gastric leiomyosarcoma Ultrasonographic endoscopy and MRI. J Radiol 1993;74:583 – 8. [12] Greget M, Veillon F, Meyer C, Tongio J, Imler M. Tumeur desmoide dans le cadre du syndrome de Gadner. A propos d’un cas e´value´ en e´chographie, TDM et IRM. J Radiol 1994;75:199 – 202. [13] Burkill GJ, Badran M, Al-Muderis O, Meirion Thomas J, Judson IR, Fisher C, Moskovic EC. Malignant gastrointestinal stromal tumor: distribution, imaging features, and pattern of metastatic spread. Radiology 2003;226:527 – 32.
MR features of gastrointestinal stromal tumors T. Caramellaa,T, S. Schmidta, P. Chevalliera, M. Saint Paulb, J.L. Bernardc, R. Bidolid, J.N. Brunetona a
Department of Radiology, Centre Hospitalier Re´gional et Universitaire de Nice, Hoˆpital Archet II, 151 route de Saint-Antoine de Ginestie`re, BP 3079, Nice 06202, France b Department of Anatomopathology, Centre Hospitalier Re´gional et Universitaire de Nice, Hoˆpital Archet II, 151 route de Saint-Antoine de Ginestie`re, BP 3079, Nice 06202, France c Department of Abdominal Surgery, Centre Hospitalier Re´gional et Universitaire de Nice, Hoˆpital Archet II, 151 route de Saint-Antoine de Ginestie`re, BP 3079, Nice 06202, France d Department of Hepatogastroenterology, Centre Hospitalier Re´gional et Universitaire de Nice, Hoˆpital Archet II, 151 route de Saint-Antoine de Ginestie`re, BP 3079, Nice 06202, France Received 29 September 2004
Abstract We report on two patients presenting with gastrointestinal stromal tumors (GIST). The important tumor size and the marked tissular hypersignal seen on T2-weighted magnetic resonance images (MRI) should be considered as magnetic resonance (MR) features strongly indicating diagnosis of GIST. D 2005 Elsevier Inc. All rights reserved. Keywords: Gastrointestinal stromal tumor (GIST); Gastrointestinal tract, MR; Gastrointestinal system, neoplasm
1. Introduction
2. Case 1
Gastrointestinal stromal tumors (GIST) are rare digestive neoplasms originating from the cells of Cajal, a complex cell network located within the bowel wall with pacemaker function. The detection of specific immunological markers has recently led to the revision of their histopathological classification [1]. They are presently defined as stromal tumors, including spindle-shaped and epithelial cells with the expression of the KIT protein (CD 117) while being of uncertain evolution [2]. We report on two cases of GISTs investigated by magnetic resonance imaging (MRI) in our department.
A 72-year-old woman was investigated for incidentally detected important hepatomegaly (Fig. 1). Ultrasonography and computed tomography (CT) had shown a hypoechogenic and hypodense mass without contrast enhancement, respectively, being in continuity with the left liver lobe without any clear demarcation from the latter. Gastroendoscopy revealed extrinsic gastric compression without intraluminal tumor; however, air insufflation was difficult and restricted. Complementary MRI was performed (Gyroscan NT10 1 T, Philipps Medical Systems, Best, The Netherlands) with fat suppressed T2-weighted spin-echo sequences (spectral presaturation with inversion recovery SPIR/TSE: TE = 80 ms, TR = 1800 ms), followed by T1-weighted gradient-echo sequences (BH: TE = 4.5 ms, TR =118 ms) before and after the intravenous injection of gadolinium at a dose of 0.2 ml/kg (Dotarem 0.5 mmol/ml; Guerbet, Roissy CdG, France).
T Corresponding author. E-mail address: [email protected] (T. Caramella). 0899-7071/05/$ – see front matter D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.clinimag.2004.12.001
252
T. Caramella et al. / Journal of Clinical Imaging 29 (2005) 251–254
on SPIR sequences relative to liver parenchyma. One could distinguish two internal components, a fibrous central hyposignal seen on T1-weighted images without enhancement, even on delayed phase after intravenous contrast medium injection, and a contrast-enhanced tissular rim. Starting in the arterial phase, enhancement was increasing towards the center during the portal phase. Tumor extension to the gastric antrum was observed measuring 25 mm in its largest diameter, indicating its gastric origin (dumbbell tumor). Four ultrasound-guided percutaneous biopsies were performed, using an automatic coaxial 14 G needle of 10-cm length (Barde, Covington, USA). Macroscopically tumor cells appeared epitheloid; immunostaining revealed the expression of KIT protein. After surgical resection, histology was confirmed. No postoperative complication occurred; no adjunct therapy was performed. Repeated MRI after 6 months did not show any tumor recurrence.
3. Case 2 An 84-year-old-woman presented with a recently appeared abdominal mass. Initial ultrasonography revealed a heterogeneous prepancreatic tumor with large central necrosis and trabecular pattern (Fig. 2). Using the same sequences as in the first patient, MRI revealed a large intraperitoneal tumor of 14 cm, strongly hyperintense on T2-weighted images. T1-weighted images after intravenous Gadolinium injection allowed the distinction of two components of this hypersignal: a central necrosis and a hypervascularized tissular rim. The strong relationship of the tumor with the stomach displaced posterioly strongly suggested gastric origin without definitive proof, however, because there was no intraluminal growth. Neither coronal nor sagittal plane could establish diagnosis. Ultrasound-guided biopsy was equally performed using the same technique as described above. Histopathology revealed a large necrotic tumor composed of spindle-shaped cells, with a strong expression of CD117 marker without mitosis.
4. Discussion Fig. 1. Case 1. (A) T2 axial SPIR: homogeneous hypersignal relative to liver parenchyma. Tumor extension to the gastric antrum is well visible (*). (B and C) T1 axial after gadolinium injection arterial and veinous phase. Two internal components: a fibrous central hyposignal without enhancement and a contrast-enhanced tissular rim.
MRI revealed a large tumor of 221130 cm extending from left subphrenic space to the middle abdomen, characterized by a strong homogeneous hypersignal seen
GISTs are rare stromal tumors representing 3.6% of gastric tumors [1]. Accounting for 5% of all gastrointestinal sarcomas, they are observed in men and women equally at a mean age of 60 years, rarely below 40 years. Seventy percent of GISTs arise from the stomach, 20% from the small bowel, and 10% from another origin (colon, rectum, and esophagus). They are mostly incidentally discovered despite an initial tumor size varying between 1 and 20 cm because there are
T. Caramella et al. / Journal of Clinical Imaging 29 (2005) 251–254
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Fig. 2. Case 2. (A) Ultrasound: heterogeneous tumor with large central necrosis and trabecular pattern. (B) T2 coronal view. Large intraperitoneal tumor strongly hyperintense. (C and D) T1 axial without and after gadolinium injection. Two internal components: a central necrosis and a hypervascularized tissular rim.
no or little specific clinical symptoms. Even large GISTs do not typically cause compression or occlusion. These tumors have rarely been described on MRI [3–7]. A recent revision of their anatomopathological classification based on immunoreactivity for KIT suggests that some of these lesions have been incorrectly identified up to now. The important tumor size at detection can conceal their exact origin. Neither endoscopy nor ultrasound in both of our cases, neither CT in one of them could clearly determine the gastric origin. MRI was able to confirm this origin in one case by visualization of intraluminal exophytic tumor growth and to indicate it strongly in the second case. The multiplanar imaging modalities of MRI might also be useful in difficult cases. Furthermore, these tumors mostly have a double morphology, i.e., a necrotic (sometimes hemorrhaged) and tissular component, both characterized as strong hypersignal on T2-weighted images relative to liver parenchyma [6,7], proven by our observations. According to our two cases, this T2-weighted hypersignal is remarkably intense: Soft tissue components showed similar hyperintensity on T2-weighted MR images as that
of cerebrospinal fluid and were difficult to distinguish from central necrosis, even being fluid. T1-weighted hypointense solid components of the tumor strongly enhanced after the intravenous Gadolinium injection seen on delayed phase images best and reflecting hypervascularization, as described on CT already [8]. In our two patients, tissular components were predominantly peripheral. The center was fibrous in the first, and necrotic in the second case. This central fibrosis has not yet been reported, according to our knowledge. In the second case, there were also focal hyperintensities on T1-weighted nonenhanced MR images, representing hemorrhage as it has already been described several times [6].
5. Differential diagnosis The most difficult differential diagnosis on MRI includes all the other mesenchymal neoplasms (leiomyomas, leiomyosarcomas, schwannomas, schwannosarcomas, neurofibromas, and neuroendocrine tumors), being the more difficult because little has been known about.
254
T. Caramella et al. / Journal of Clinical Imaging 29 (2005) 251–254
Gastric schwannoma [9] show slight hyperintensity on T1-weighted and moderately to strongly hypersignal on T2-weighted MR images. After the intravenous injection of Gadolinium, slow but homogeneous contrast enhancement is observed. Leiomyomas have mostly been described as masses arising from the uterus [10] with a low signal intensity on T2-weighted MR images and an isosignal relative to the myometrium on T1-weighted MR images enhancing strongly after intravenous Gadolinium injection. Gastric leiomyoma [11] may demonstrate central T2-weigted hyperintensity due to pseudocystic transformation. There might also be a horizontal hypointense level seen on T1- and T2-weighted MR images resulting from former hemorrhage. The size of these two benign tumors, gastric schwannoma and leiomyoma, is mostly small, which is inferior to 5 cm. Leiomyosarcoma demonstrates central necrosis with focal parietal contrast enhancement. For sure, this is the tumor with the most similar MR characteristics to GISTs. In case of tumor dissemination, radiological appearance of secondary liver lesions may help because liver metastases due to leiomyosarcoma are hypervascularized, therefore best seen on early phase after intravenous contrast enhancement. Epidemiologically, leimoyomas, leiomyosarcomas, and schwannomas exceptionnally arise from the stomach, in any case, far less often than GISTs. All these tumors are hypervascularized lesions on CT [8]. The other differential diagnoses include large solid abdominal masses. Adenocarcinomas only rarely demonstrate exophytic growth [6], but more often cause hemorrhage and luminal stenosis; therefore, symptoms appear at an earlier stage as with GISTs. Because adenocarcinomas are known for primarily lymphatic dissemination, epigastric and pericoeliac lymph node metastases rapidly occur, which is not typically seen with GISTs metastasizing in lymph nodes exceptionally only. Desmoid tumors are rare and benign, but frequently recurrent tumors, isolated or associated with Gardener syndrome. The main localization is the mesentery. Classic MRI features are hypointensity on T1- and T2-weighted sequences. There might also be a moderate hypersignal on T2-weighted MR images; contrast enhancement has never been reported after intravenous Gadolinium injection [12]. Histological diagnosis of GISTs can easily be obtained by imaging guided biopsy. Several authors report on the complications after biopsy because of skin metastases found along the needle path [13]. Therefore, we recommend a sheath of protection by using a coaxial system, allowing for multiple core biopsy while avoiding skin contamination. Ideally, you might mark the point of incision on the skin for later excision during surgical intervention. The potential curative treatment of GIST is complete surgical resection. Prognosis is serious, with mean survival of 20 months in case of tumor dissemination [1].
Recently, a new molecule, Imatinib (Glivec, Novartis, Switzerland), a specific KIT-receptor inhibitor, has increasingly been used for the chemotherapy of GIST. Although published on a limited series only, first results are very promising. The main indication is, at present, primarily metastasizing tumors, but it might also be used for adjuvant or neoadjuvant treatment in the future [1].
6. Conclusion Based on tumor features of localization, volume, and signal intensity, the diagnosis of GIST can be advocated on MRI.
References [1] Connolly EM, Gaffney E, Reynolds JV. Gastrointestinal stromal tumours. Br J Surg 2003;90:1178 – 86. [2] Petitjean B, Beaulieu S, Loubouti-Sanchez A, Bergue A. Tumeurs stromales digestives: Anatomopathologie, diagnostic et traitement. Encycl Me´d Chir (Editions Scientifiques Me´dicales Elsevier SAS, Paris), Gastro-enterologie, 9-027-A-15, 2003 [6 pp]. [3] Hasegawa S, Semelka RC, Noone TC, Woosley JT, Marcos HB, Kenney PJ, Siegelman ES. Gastric stromal sarcomas: correlation of MR imaging and histopathologic findings in nine patients. Radiology 1998;208:591 – 5. [4] Naitoh I, Okayama Y, Masaaki H, Kitajima Y, Hayashi K, Okamoto T, Akita S, Gotoh K, Mizusima M, Sano H, Ohara H, Nomura T, Joh T, Yokoyama Y, Itoh M. Exophytic pedunculated gastrointestinal stromal tumor with remarkable cystic change. J Gastroenterol 2003;38: 1181 – 4. [5] Mignon F, Julie C, Izzillo R, Luciani A, Guichoux F, Mesurolle B, El Hajam M, Qanadli SD, Chagnon S, Lacombe P. Imaging features of gastric stromal tumors: radiologic–pathologic correlation. Report of 4 cases. J Radiol 2000;81:875 – 81. [6] Levy AD, Remotti HE, Thompson WM, Sobin LH, Miettinen M. Gastrointestinal stromal tumors: radiologic features with pathologic correlation. Radiographics 2003;23:283 – 304. [7] Jost D, Stroszczynski C, Chmelik P, Gaffke G, Schlecht I, Pink D, Reichart P, Schneider U, Hohenberger P, Felix R. Morphologie gastrointestinaler Stromatumoren im fortgeschrittenen Stadium der Erkrankung: Ausgangsbefunde vor Chemotherapie mit Imatinib. Fortschr Rfntgenstr 2003;175:791 – 8. [8] Ghanen N, Altehoefer C, Furtwangler A, Winterer J, Schafer O, Springer O, Kotter E, Langer M. Computed tomography in gastrointestinal stromal tumors. Eur Radiol 2003;13:1669 – 78. [9] Karabulut N, Martin DR, Yang M. Case report: gastric schwannoma: MRI findings. Br J Radiol 2002;75:624 – 6. [10] Szklaruk J, Tamm EP, Haesun C, Varavithya V. MR Imaging of common and uncommon large pelvic masses. Radiographics 2003;23: 403 – 24. [11] Marcy PY, Franc¸ois E, Bruneton JN, Peroux JL, Balu-Maestro C, Melia P, Dubruque F, Aviotti-Gasperoni A. Gastric leiomyosarcoma Ultrasonographic endoscopy and MRI. J Radiol 1993;74:583 – 8. [12] Greget M, Veillon F, Meyer C, Tongio J, Imler M. Tumeur desmoide dans le cadre du syndrome de Gadner. A propos d’un cas e´value´ en e´chographie, TDM et IRM. J Radiol 1994;75:199 – 202. [13] Burkill GJ, Badran M, Al-Muderis O, Meirion Thomas J, Judson IR, Fisher C, Moskovic EC. Malignant gastrointestinal stromal tumor: distribution, imaging features, and pattern of metastatic spread. Radiology 2003;226:527 – 32.