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CT VS MRI

I have had this conversation with Dr. Von Mehren at Fox Chase many times during the 9 years I have had GIST. She honestly says that it is easier for her to read the CT than the MRI. She further says that she thinks the CT can detect abdominal GISTs better, but admits that a very trained radiologist can probably track them sufficiently. I think she likes to read the scans herself and she can do that quicker than the MRI. I think also that not all MRI machines are created equal.

I just wonder if in time, more people will be trying MRIs since there is such talk lately about the radiation exposure and we are living longer now. Maybe the technology will be advancing to limit the radiation.


Dr. Haesun Choi (expert radiologist for GIST at MD Anderson) addressed MRIs in a recent paper, and here is the quote:

"MRI is superior to contrast-enhanced CT in evaluating the hepatic metastasis and rectal GIST with superior soft-tissue contrast and direct multiplanar acquisition capability. However, MRI is not the primary imaging modality of choice in evaluating GIST patients because of its general limited sensitivity in detecting peritoneal tumors. However, thorough analysis of well-designed, dedicated MRI (thin-section, such as <5 mm, fat-saturated T1-weighed images), can provide good visualization of the peritoneal cavity in most patients.

On MRI, GISTs are generally well defined; the solid portions of the masses are typically of low- to intermediate-signal intensity on T1-weighted images and high signal intensity on T2-weighted images. As in CT, the tumors enhance after administration of an intravenous contrast agent.56 Intravenous contrast helps to delineate viable solid oomponents and nonenhanced necrotic areas. Internal hemorrhage may have signal intensity varying from high to low on both T1- and T2-weighted images, depending on the age.57 MRI can be used to differentiate the possible high-density intratumoral mass shown on CT images from hemorrhage. Dynamic contrast-enhanced MRI can be used to evaluate tumor viability and to quantitate the status of angiogenesis. However, to the authors' knowledge, no published series has evaluated the value of this imaging technique in management of GISTs."end of quote


So the one drawback of MRI is greater difficulty in detecting peritoneal mets, but Dr. Choi seems to be suggesting techniques to get around that.

Below are some abstracts about using MRI for GIST and other peritoneal tumors. MRI is clearly better than CT for the liver. Its only deficiency is for the mesentery and peritoneum. So these papers address that. If you have impaired kidney function, if you are allergic to iodine dye, or if you want to reduce radiation, then you can talk with your radiologist and oncologist about MRI.

Here is a paragraph from the Levy Shaw & Sobin paper (first abstract below):

"Although magnetic resonance imaging (MRI) is not as widely used as CT for imaging the peritoneal cavity, its superior contrast resolution makes it very useful for evaluating the peritoneal cavity. Peritoneal carcinomatosis enhances slowly after the intravenous administration of gadolinium and therefore is best shown on images obtained 5-10 minutes after injection. Because the normal peritoneum enhances similar to the degree of enhancement in the liver, abnormal enhancement should be suspected when the peritoneum is enhancing greater than the liver or has associated thickening, nodularity, or mass (15). Conventional CT has a low sensitivity (60%-79%) for the detection of peritoneal carcinomatosis (12,16). In more recent studies, in which helical CT scanners were used, CT demonstrated improved overall sensitivity (85%-93%) but poor sensitivity (25%-50%) for detection of tumor implants less than 1 cm (17). In contrast, MR imaging has been shown to have better sensitivity (85%-90%) than CT for the detection of tumor nodules less than 1 cm and an overall sensitivity for all peritoneal tumor nodules of 84% (18)." end of quote


Radiographics. 2009 Mar-Apr;29(2):347-73.

Secondary tumors and tumorlike lesions of the peritoneal cavity: imaging features with pathologic correlation.

Levy AD, Shaw JC, Sobin LH.

Department of Radiology and Radiological Sciences, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799, USA. alevy@usuhs.mil

Tumors and tumorlike lesions that secondarily involve the mesothelial or submesothelial layers of the peritoneum are a diverse group of disorders that range in biologic behavior from benign to highly malignant. The anatomy of peritoneal ligaments and mesenteries and the normal circulation of peritoneal fluid dictate location and distribution of these diseases within the peritoneal cavity. Peritoneal carcinomatosis is the most common secondary tumor to affect the peritoneal cavity. When it arises from carcinomas of the gastrointestinal tract or ovary, the prognosis is grave. However, when low-grade mucinous adenocarcinoma of the appendix spreads to the peritoneal cavity, the consequence is typically pseudomyxoma peritonei, which is a clinical syndrome, characterized by recurrent and recalcitrant voluminous mucinous ascites due to surface growth on the peritoneum without significant invasion of underlying tissues. Carcinomas from elsewhere in the body, as well as lymphomas and sarcomas, may also produce diffuse peritoneal metastasis. Granulomatous peritonitis is the consequence of disseminated infection such as tuberculosis or histoplasmosis, foreign materials, or rupture of a tumor or hollow viscus. Finally, a group of benign miscellaneous conditions that range from common disorders such as endometriosis and splenosis to very rare conditions such as gliomatosis peritonei and melanosis may also affect the peritoneum diffusely. Secondary tumors and tumorlike lesions of the peritoneum have overlapping imaging features when compared with each other and primary peritoneal tumors. Knowledge of peritoneal anatomy, normal fluid circulation within the peritoneal cavity, and clinical and pathologic features of secondary peritoneal lesions is essential for identification of these lesions.

PMID: 19325052 [PubMed - indexed for MEDLINE] FREE ACCESS to full paper at this link


AJR Am J Roentgenol. 2009 Aug;193(2):461-70.

Diffusion-weighted MRI of peritoneal tumors: comparison with conventional MRI andsurgical and histopathologic findings--a feasibility study.

Low RN, Sebrechts CP, Barone RM, Muller W.


OBJECTIVE: The purpose of our study was to evaluate the utility of single-shot spin-echo echo-planar diffusion-weighted imaging (DWI) using a b value of 400-500 s/mm(2) for depicting peritoneal tumors. MATERIALS AND METHODS: Thirty-four consecutive oncology patients underwent preoperative abdominal and pelvic MRI for tumor staging. MRI included breath-hold DWI with a b value of 400-500 s/mm(2),T1-weighted spoiled gradient-echo, T2-weighted fast spin-echo, and 0- and 5-minute delayed gadolinium-enhanced imaging. At three separate sessions, two observers independently reviewed images for peritoneal tumors at 16 anatomic sites. First DWI alone was reviewed, followed by conventional MRI alone, and then conventional MRI, including DWI, was reviewed. Results of laparotomy and histopathologic evaluation were compared with MRI results. Sensitivity, specificity, and accuracy were calculated for DWI, conventional MRI, and combined DWI and conventional MRI for peritoneal tumor depiction. RESULTS: Two-hundred fifty-five sites of peritoneal tumor were proven by surgical and histopathologic findings. The combination of DWI and conventional MRI was most sensitive and accurate for peritoneal tumors, depicting 230 and 214 tumor sites for the two observers (sensitivity, 0.90, 0.84; and accuracy, 0.91, 0.88) compared with DWI alone, which depicted 182 and 182 tumor sites with sensitivity (0.71, 0.71; and accuracy, 0.81, 0.81), and conventional MRI alone, which depicted 185 and 132 tumor sites (sensitivity, 0.73, 0.52; and accuracy, 0.81, 0.72). Peritoneal tumor showed restricted diffusion on DWI and ascites was of low signal intensity, increasing tumor conspicuity. CONCLUSION: Adding DWI to routine MRI improves the sensitivity and specificity for depicting peritoneal metastases. Breath-hold DWI is now routinely used in all oncology patients referred for abdominal MRI at our institution.

PMID: 19620444 [PubMed - indexed for MEDLINE]



J Magn Reson Imaging. 2007 Apr;25(4):848-58.

Diffusion-weighted MRI (DWI) in the oncology patient: value of breathhold DWI compared to unenhanced and gadolinium-enhanced MRI.

Low RN, Gurney J.

Children's MRI Center, San Diego, California 92123, USA. rlow@ucsd.edu

PURPOSE: To evaluate the feasibility and added value of single breathhold diffusion-weighted (DW) imaging (DWI) in oncology patients undergoing abdominal MRI. MATERIALS AND METHODS: A total of 169 patients with malignancy underwent abdominal MRI at 1.5T, including T1-weighted (T1W), T2-weighted (T2W), and dynamic gadolinium-enhanced imaging. Axial DWI was performed with a single-shot spin-echo (SE) echo-planar imaging (EPI) sequence using a b-value of 500 seconds/mm2. A total of 24 slices were obtained during a 20-second breathhold. Two observers reviewed the conventional MR images for tumor. Next, the DW images were reviewed for additional tumor not depicted on conventional MR images RESULTS: For the 169 patients, additional tumors were noted on the DW images in 77 (0.46) for observer 1 and 67 (0.40) for observer 2. For observer 1 the additional tumor included lymphadenopathy (47), peritoneal metastases (15), renal (1), liver (12), and osseous (2), while for observer 2 the corresponding values were lymphadenopathy (40), peritoneal (12), renal (1), liver (6), osseous (4), and gastrointestinal (1). The DW images resolved as benign findings noted on the conventional MR images in three patients for observer 1 and four patients for observer 2. The conventional MR exam was entirely normal while the DW images showed tumor in 12 (0.07) patients for observer 1 and 10 (0.06) patients for observer 2. CONCLUSION: DWI is feasible in a single breathhold and provides additional clinically important information in oncology patients when added to routine abdominal MR sequences. Copyright (c) 2007 Wiley-Liss, Inc.

PMID: 17335018 [PubMed - indexed for MEDLINE]


Diagn Interv Radiol. 2009 Jun;15(2):121-6.

Radiologic findings in malignant gastrointestinal stromal tumors.

Ulusan S, KoƧ Z.

Department of Radiology, Baskent University School of Medicine, Adana, Turkey. sulusan@hotmail.com

In this pictorial essay, we describe the computed tomographic and magnetic resonance imaging appearances of primary and metastasized gastrointestinal stromal tumors. These nonepithelial tumors arise from the muscularis propria in the wall of the gastrointestinal tract and are thought to originate from Cajal cells in the interstitium of intestinal pacemaker tissue. These tumors are found in the stomach, small bowel, colon, rectum, and esophagus; they may also develop as primary tumors of the omentum, mesentery, or retroperitoneum. The clinical features and radiologic differential diagnosis of gastrointestinal stromal tumorsare discussed.

PMID: 19517382 [PubMed - indexed for MEDLINE]



Here are more papers relevant to this topic. You can link to PubMed to read the abstracts, and several are FREE access to read the entire paper. You can show this list to your radiologist if you want to discuss MRI for GIST monitoring.


1: Amano M, Okuda T, Amano Y, Tajiri T, Kumazaki T. Magnetic resonance imaging of gastrointestinal stromal tumor in the abdomen and pelvis. Clin Imaging. 2006 Mar-Apr;30(2):127-31. PubMed PMID: 16500544.


2: Antoch G, Herrmann K, Heusner TA, Buck AK. [Imaging procedures for gastrointestinal stromal tumors]. Radiologe. 2009 Dec;49(12):1109-16. Review. German. PubMed PMID: 19787329.


3: Caramella T, Schmidt S, Chevallier P, Saint Paul M, Bernard JL, Bidoli R, Bruneton JN. MR features of gastrointestinal stromal tumors. Clin Imaging. 2005 Jul-Aug;29(4):251-4. PubMed PMID: 15967315.


4: Chourmouzi D, Sinakos E, Papalavrentios L, Akriviadis E, Drevelegas A. Gastrointestinal stromal tumors: a pictorial review. J Gastrointestin Liver Dis. 2009 Sep;18(3):379-83. Review. PubMed PMID: 19795038. FREE ACCESS


5: Crusco F, Pugliese F, Maselli A, Pelliccia G, Mariani E, Farroni F, Giovagnoni A. Malignant small-bowel neoplasms: spectrum of disease on MR imaging. Radiol Med. 2010 Dec;115(8):1279-91. Epub 2010 Sep 17. Review. English, Italian. PubMed PMID: 20852962.


6: Koike N, Cho A, Nasu K, Seto K, Nagaya S, Ohshima Y, Ohkohchi N. Role of diffusion-weighted magnetic resonance imaging in the differential diagnosis of focal hepatic lesions. World J Gastroenterol. 2009 Dec 14;15(46):5805-12. PubMed PMID: 19998501; PubMed Central PMCID: PMC2791273. FREE ACCESS


7: Kyriazi S, Collins DJ, Morgan VA, Giles SL, deSouza NM. Diffusion-weighted imaging of peritoneal disease for noninvasive staging of advanced ovarian cancer. Radiographics. 2010 Sep;30(5):1269-85. PubMed PMID: 20833850.


8: Levy A, Medjhoul A, Caramella C, Zareski E, Berges O, Chargari C, Boulet B, Bidault F, Dromain C, Balleyguier C. Interest of diffusion-weighted echo-planar MR imaging and apparent diffusion coefficient mapping in gynecological malignancies: a review. J Magn Reson Imaging. 2011 May;33(5):1020-7. doi: 10.1002/jmri.22546. PubMed PMID: 21509857.


9: Levy AD, Shaw JC, Sobin LH. Secondary tumors and tumorlike lesions of the peritoneal cavity: imaging features with pathologic correlation. Radiographics. 2009 Mar-Apr;29(2):347-73. Review. PubMed PMID: 19325052. FREE ACCESS


10: Lewis RB, Lattin GE Jr, Makhlouf HR, Levy AD. Tumors of the liver and intrahepatic bile ducts: radiologic-pathologic correlation. Magn Reson Imaging Clin N Am. 2010 Aug;18(3):587-609, xii. Review. PubMed PMID: 21094457.


11: Low RN, Sebrechts CP, Barone RM, Muller W. Diffusion-weighted MRI of peritoneal tumors: comparison with conventional MRI and surgical and histopathologic findings--a feasibility study. AJR Am J Roentgenol. 2009 Aug;193(2):461-70. PubMed PMID: 19620444. FREE ACCESS


12: Murphey MD, Ruble CM, Tyszko SM, Zbojniewicz AM, Potter BK, Miettinen M. From the archives of the AFIP: musculoskeletal fibromatoses: radiologic-pathologic correlation. Radiographics. 2009 Nov;29(7):2143-73. PubMed PMID: 19926768. FREE ACCESS


13: Nasu K, Kuroki Y, Sekiguchi R, Nawano S. The effect of simultaneous use of respiratory triggering in diffusion-weighted imaging of the liver. Magn Reson Med Sci. 2006 Oct;5(3):129-36. PubMed PMID: 17139138. FREE ACCESS


14: Nasu K, Kuroki Y, Nawano S, Kuroki S, Tsukamoto T, Yamamoto S, Motoori K, Ueda T. Hepatic metastases: diffusion-weighted sensitivity-encoding versus SPIO-enhanced MR imaging. Radiology. 2006 Apr;239(1):122-30. Epub 2006 Feb 21. PubMed PMID: 16493012. FREE ACCESS


15: Shankar S, Dundamadappa SK, Karam AR, Stay RM, van Sonnenberg E. Imaging of gastrointestinal stromal tumors before and after imatinib mesylate therapy. Acta Radiol. 2009 Oct;50(8):837-44. Review. PubMed PMID: 19735005.


16: Stroszczynski C, Jost D, Reichardt P, Chmelik P, Gaffke G, Kretzschmar A, Schneider U, Felix R, Hohenberger P. Follow-up of gastro-intestinal stromal tumours (GIST) during treatment with imatinib mesylate by abdominal MRI. Eur Radiol. 2005 Dec;15(12):2448-56. Epub 2005 Aug 13. PubMed PMID: 16132930.


17: Szklaruk J, Tamm EP, Choi H, Varavithya V. MR imaging of common and uncommon large pelvic masses. Radiographics. 2003 Mar-Apr;23(2):403-24. Review. PubMed PMID: 12640156. FREE ACCESS


18: Wang Y, Miller FH, Chen ZE, Merrick L, Mortele KJ, Hoff FL, Hammond NA, Vahid Y, Nikolaidis P. Diffusion-weighted MR imaging of solid and cystic lesions of the pancreas. Radiographics. 2011 May-Jun;31(3):E13-30. PubMed PMID: 21721197.