Search

Objective: To retrospectively assess the value of adding gadolinium-enhanced dynamic imaging to standard ununenhanced magnetic resonance imaging (MRI) for characterising hypoattenuating hepatic lesions that are too small to characterise with multi-detector computed tomography (MDCT).Methods: Informed consent was waved, and institutional review board approval was obtained. Three hundred and forty-six small (≤ 2 cm) lesions (63 metastatic, 283 benign) in 183 patients with underlying carcinoma who underwent hepatic MRI after CT were retrospectively analysed. Two radiologists independently reviewed images and diagnoses were graded on an ordinal scale from 1 (definitely benign) to 5 (definitely malignant). Receiver operating characteristic analysis was used. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were also determined.Results: The areas under the curve of the ununenhanced images alone and with dynamic images were 0.837 and 0.850 for reader 1 (p = 0.616) and 0.771 and 0.783 for reader 2 (p = 0.700). Descriptive statistical values demonstrated sensitivities of 76% and 80%, specificities of 93% and 95%, PPVs of 69% and 79%, NPVs of 95% and 95% and accuracies of 90% and 92%, respectively.Conclusion: The value of adding three-phase contrast-enhanced MRI to unenhanced imaging did not reach statistical significance for characterising small hypoattenuating hepatic lesions on MDCT. [ABSTRACT FROM AUTHOR]

Objective: To determine whether intravenous administration of gadoxetic acid disodium (Gd-EOB-DTPA) affects lesion conspicuity and apparent diffusion coefficient (ADCs) in diffusion-weighted imaging (DWI) for hepatic magnetic resonance imaging (MRI) at 3.0 T.Methods: Thirty-four patients with 50 focal hepatic lesions (18 hepatocellular carcinomas, 12 metastases, 1 cholangiocarcinoma, 7 haemangiomas, 12 cysts) underwent DWI at 3.0 T before and after administration of Gd-EOB-DTPA. Non-breath-hold DWI was performed with b values of 0, 200, 400 and 800 s/mm(2). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of each lesion, and ADCs of the liver and lesion were calculated for unenhanced and enhanced images. Statistical differences between unenhanced and enhanced data were assessed.Results: SNRs and ADCs of the liver on enhanced images were significantly lower than on unenhanced images. On DW images at b = 200 s/mm(2), CNRs of malignant and overall lesions were significantly higher on enhanced than on unenhanced images. CNRs of focal lesions tended to be higher, especially in malignant lesions, on DW images at b = 0 and 400 s/mm(2), but without reaching statistical significance. ADCs of focal hepatic lesions were not significantly different before and after administration of contrast agent.Conclusion: DWI after Gd-EOB-DTPA administration can be used as a substitute for unenhanced DWI at 3.0 T without compromising CNR and ADC of focal hepatic lesions. [ABSTRACT FROM AUTHOR]

We examined 20 prediagnostic CTs from 16 patients for whom the diagnosis of pancreatic cancer was delayed until full diagnostic CT was performed. Three radiologists independently reviewed the prediagnostic CTs along with 50 CTs of control subjects, including patients without pancreatic disease (n = 38) or with chronic pancreatitis without calcification visible on CT (n = 12). The reviewers recorded the presence of biliary or pancreatic ductal dilation, interruption of the pancreatic duct, distal parenchymal atrophy, contour abnormality and focal hypoattenuation. Frequency, sensitivity and specificity of the significant findings were calculated. Logistic regression analysis was performed. Findings indicative of pancreatic cancer were seen on 85% (17/20) of the prediagnostic CTs. Patients with pancreatic cancer were significantly (p < 0.05) more likely to show focal hypoattenuation, pancreatic duct dilation, interruption of the pancreatic duct, and distal parenchymal atrophy, with sensitivities and specificities of 75%/84%, 50%/78%, 45%/82% and 45%/96%, respectively. Focal hypoattenuation and distal parenchymal atrophy were the independent predictors of pancreatic cancer with odds ratios of 20.92 and 11.22, respectively. In conclusion, focal hypoattenuation and pancreatic duct dilation with or without interruption, especially when accompanied by distal parenchymal atrophy, were the most useful findings for avoiding delayed diagnosis of pancreatic cancer. [ABSTRACT FROM AUTHOR]

Gastric submucosal tumors (SMTs) consist of various lesions arising from the deep layers of the stomach. Gastrointestinal stromal tumors (GISTs) are undoubtedly the commonest malignant SMTs of the stomach, and therefore the attitude towards the general diagnostic approach for GISTs defines the extended diagnostic plan for SMTs. Two recent consensus meetings were assembled concerning the classification and therapeutic plans for GISTs. These meetings shed light upon the need for the modification of the current role of imaging modalities, including endoscopic ultrasound (EUS) and computed tomography (CT). According to the revised concepts of GISTs, the most important and plausible current role of imaging for the diagnostic approach of gastric SMTs is to differentiate GISTs from other gastric SMTs. This review discusses the newly established diagnostic role of radiology according to the revised classification of GISTs and provides the differential diagnoses based on EUS and CT findings. [ABSTRACT FROM AUTHOR]