Signal characteristic and enhancement patterns of pancreatic adenocarcinoma: evaluation with dynamic gadolinium enhanced MRI.
ABSTRACT To determine the signal characteristics and enhancement patterns of proven pancreatic adenocarcinomas at 1.5 T and to compare these results with contrast enhanced computed tomography (CECT).
Twenty-five patients, mean age 73 years, with proven pancreatic adenocarcinoma were imaged at 1.5 T using in- and opposed-phase, gradient-echo (GRE), T1-weighted sequences, T2 weighting using either a short tau inversion recovery (STIR) or frequency selective, fat-suppressed turbo spin echo (TSE) sequence, and with a three-dimensional (3D), fat-suppressed, GRE T1 sequence before, during the arterial, venous, and equilibrium phases after Gadolinium administration. Fourteen of the 25 patients underwent CECT. Magnetic resonance imaging (MRI) examinations were evaluated by two observers in consensus for size, signal characteristics, and enhancement patterns, and the results were compared with CECT.
The mean size of pancreatic adenocarcinomas was 32 mm. On unenhanced T1-weighted images, 12 of 25 lesions (48%) were hypointense, 13 (52%) were isointense. On STIR/T2, 11 of 25 (44%) pancreatic adenocarcinomas were hyperintense, 14 (56%) were isointense. All 25 (100%) adenocarcinomas were hypointense during the arterial phase. Twenty (80%) and 17 (68%) remained hypointense in the venous phase and equilibrium phases, respectively. In seven of 14 (50%) cases, the pancreatic mass was iso-attenuating to the pancreatic parenchyma during both the pancreatic and venous phases of CECT.
The results of the present study showed that all 25 pancreatic adenocarcinomas were hypointense to pancreatic parenchyma during the arterial phase. Moreover, MRI may be useful in patients with a high suspicion of pancreatic carcinoma that is not visualized during CECT.
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ABSTRACT: The prognosis for pancreatic cancer is poor, and early diagnosis is essential for surgical management. By comparison with its classic form, the presence of acute or chronic inflammatory signs will hinder its detection and delay its diagnosis. The atypical forms of acute pancreatitis need to be known in order to detect patients who require additional morphological investigations to search for an underlying tumour. In contrast, pseudotumoral forms of inflammation (chronic pancreatitis, cystic dystrophy in heterotopic pancreas, autoimmune pancreatitis) may simulate a cancer, and make up 5-10% of the surgical procedures for suspected cancer. Faced with these pseudotumoral masses, interpretation relies on various differentiating signs and advances in imaging.06/2013; 46. DOI:10.1016/j.diii.2013.03.013
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ABSTRACT: OBJECTIVE. The purpose of this article is to evaluate factors associated with the likelihood that abdominopelvic MRI examinations performed for characterization of lesions identified on other imaging modalities will provide information that adds value to patient management. MATERIALS AND METHODS. One thousand one hundred thirty-two lesions in 863 patients undergoing MRI for further characterization after detection by an alternative imaging modality were identified. Reports of the MRI examinations and of previous studies were reviewed to classify cases in terms of patient-, examination-, and lesion-related factors. MRI reports were also classified in terms of measures reflecting inclusion of content with the potential to add value to patient management. Data were analyzed using logistic regression for correlated data. RESULTS. MRI provided a definitive diagnosis in 79.2% (897/1132), upgraded the severity of the favored diagnosis in 5.3% (60/1132), downgraded the severity of the favored diagnosis in 34.5% (390/1132), and showed an absence of the suspected lesion in 12.1% (137/1132) of cases. Provision of a definitive diagnosis (most common in liver, kidney, gallbladder, bowel, myometrium, and adrenal gland) was significantly associated with the organ containing the lesion (p < 0.001). A change in severity of the favored diagnosis (most common after CT or PET/CT) and the absence of the suspected lesion (most common after PET/CT) were significantly associated with the prior imaging modality (p ≤ 0.001). Among the lesions that were upgraded in severity, 76.7% subsequently underwent intervention or change in medical management. CONCLUSION. Abdominopelvic MRI examinations performed for further lesion characterization may affect clinical management in a high fraction of cases, the likelihood of which is influenced by factors related to the given examination.American Journal of Roentgenology 05/2014; 202(5):1037-42. DOI:10.2214/AJR.13.11071 · 2.74 Impact Factor
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ABSTRACT: To identify the MRI sequences producing the greatest pancreatic adenocarcinoma conspicuity and to assess correlations linking MRI signal intensity and apparent diffusion coefficient to histopathological findings. We retrospectively included 22 patients with pancreatic adenocarcinoma who underwent MRI (1.5 or 3 T) before surgical resection. Fat-suppressed (FS) T1- and T2-weighted sequences; 3D FS dynamic T1-weighted gadolinium-enhanced gradient-echo (GRE) imaging at the arterial, portal, and delayed phases; and diffusion-weighted imaging (DWI) with b values of 600-800 s/mm(2) were reviewed. On each sequence, we assessed tumor conspicuity both qualitatively (3-point scale) and quantitatively (tumor-to-proximal and -distal pancreas contrast ratios), and we performed paired Wilcoxon tests to compare these data across sequences. We evaluated correlations between histopathological characteristics and MRI features. 21/22 (95%) tumors were hypointense by 3D FS T1 GRE arterial phase imaging, which produced the greatest tumor conspicuity (p a parts per thousand currency sign 0.02). By DWI, 5/20 (25%) of tumors were isointense. The correlation between size by histology and MRI was strongest with DWI. A progressive enhancement pattern was associated with extensive and dense fibrous stroma (p a parts per thousand currency sign 0.03). 3D FS T1 GRE arterial phase imaging produces greater pancreatic adenocarcinoma conspicuity compared to DWI but underestimates tumor size. DWI provides the best size evaluation but fails to delineate the tumor in one-fourth of cases.Abdominal Imaging 07/2014; 40(1). DOI:10.1007/s00261-014-0196-8 · 1.73 Impact Factor