Sukru Mehmet Erturk

High-b Value Diffusion-Weighted MRI for Detecting Pancreatic Adenocarcinoma: Preliminary Results

OBJECTIVE The objective of our study was to evaluate the usefulness of high-b value diffusion-weighted MRI (DWI) in the detection of pancreatic adenocarcinoma. SUBJECTS AND METHODS Twenty-six patients with pancreatic adenocarcinoma were included in the study. Twenty-three other patients who were being followed up due to pancreatic diseases other than adenocarcinoma were included as control subjects. All patients and subjects underwent DWI, and the images were evaluated by three blinded radiologists. RESULTS Receiver operating characteristic (ROC) curve analysis yielded A(z) values (i.e., area under the ROC curve) of 0.998, 0.998, and 0.995 for the three radiologists. The mean sensitivity and specificity for the detection of pancreatic adenocarcinoma were 96.2% and 98.6%, respectively. The kappa values indicating interobserver agreement between different pairs of radiologists were in the category of excellent. CONCLUSION High-b value DWI allows the detection of pancreatic adenocarcinoma with a high sensitivity and specificity.

High-B-value diffusion-weighted MRI in colorectal cancer.

OBJECTIVE The purpose of this article is to evaluate the usefulness of high-b-value diffusion-weighted MRI (DW-MRI) in the detection of colorectal adenocarcinoma. CONCLUSION High-b-value DW-MRI allows detection of colorectal adenocarcinoma with a high sensitivity and specificity.

Computed tomography features of nonalcoholic steatohepatitis with histopathologic correlation

Objective: This study was conducted to describe the computed tomography (CT) features of nonalcoholic steatohepatitis (NASH) and to evaluate if the CT features could be used to diagnose and stage NASH. Methods: From 1994 until 2004, pathology records revealed 68 patients with NASH. Of these, 12 patients underwent CT scans before (n = 6), on the same day as (n = 3), or after (n = 3) a liver biopsy. Using the same database, 9 patients with steatosis alone evaluated with a CT scan before (n = 2), on the same day as (n = 3), or after (n = 4) the liver biopsy were selected as a control group. Two radiologists measured liver attenuation (compared with spleen) and assessed the pattern of steatosis, craniocaudal liver span, caudate-to-right lobe ratio, preportal space distance, and presence of porta hepatis lymph nodes and ascites. Biopsy specimens were assessed by a pathologist, and the degree of necroinflammatory activity, steatosis, and fibrosis was determined. Histopathologic and CT findings were compared between patients with NASH and patients with steatosis alone using the Mann-Whitney U test and Fisher exact test. Results: In patients with NASH, the mean liver-to-spleen attenuation ratio was 0.66 (range: 0.1-1.1). Steatosis was diffuse (n = 9), geographic or nonlobar (n = 2), or diffuse with an area of focal sparing (n = 1). The liver craniocaudal span varied from 17.5 to 25.5 cm (mean = 21.4 cm), and hepatomegaly was present in 11 (91.7%) patients. The caudate-to-right-lobe ratio (mean = 0.43) and preportal space (mean = 4.5 mm) were normal in all cases. Porta hepatis lymph nodes were present in 7 (58.3%) patients; their mean dimensions were 16 mm × 11 mm. Ascites was absent in all patients. On histopathology, the degree of necroinflammatory activity was mild (n = 9), moderate (n = 1), or severe (n = 2). The degree of steatosis was 33% to 66% (n = 5) or >67% (n = 7). All but 3 patients had fibrosis; 6 had focal nonbridging fibrosis, 1 had multifocal nonbridging fibrosis, and 2 had bridging fibrosis. There was a significant correlation between the degree of steatosis on pathologic examination and the liver-to-spleen attenuation ratio on CT (P = 0.048). The severity of inflammation and stage of fibrosis on pathologic examination did not correlate with the CT features. Among patients with steatosis alone, the mean liver-to-spleen attenuation ratio was 0.80 (range: 0.3-1.2); the craniocaudal liver span varied from 12 to 20 cm (mean = 16 cm); hepatomegaly was present in 2 (22.2%) patients; the caudate-to-right lobe ratio was normal in all patients, with a mean of 0.36 (range: 0.22-0.47); the preportal space distance was enlarged in 2 cases (mean = 7.5 mm, range: 1-16 mm); porta hepatis lymph nodes were present in 7 (77.8%) patients, and their mean dimensions were 11 mm × 8 mm (large axis range: 6-19 mm, short axis range: 4-14 mm); and no patient had ascites. There was a significant difference in the craniocaudal liver span between patients with NASH (mean = 21 cm) and patients with steatosis (mean = 16 cm) (P < 0.05). The caudate-to-right-lobe ratio was also significantly different between patients with NASH (mean = 0.43) and patients with steatosis (mean = 0.36) (P < 0.05). There were no significant differences in liver-to-spleen attenuation ratios, measurements of preportal space, or the presence of porta hepatic lymph nodes. Conclusion: The CT features of NASH include steatosis, hepatomegaly, and porta hepatis lymph nodes, and the liver-to-spleen attenuation ratio correlated with the degree of steatosis on histopathology. Patients with NASH had a greater liver span and increased caudate-to-right-lobe-ratio compared with patients with steatosis alone.

CT-Guided Percutaneous Catheter Drainage of Acute Necrotizing Pancreatitis: Clinical Experience and Observations in Patients with Sterile and Infected Necrosis

OBJECTIVE The purpose of this study was to report on clinical experience with and observations made during primary CT-guided percutaneous catheter drainage of acute necrotizing pancreatitis and to compare results among patients with sterile and those with infected necrosis. MATERIALS AND METHODS We reviewed clinical, radiologic, and bacteriologic data on 35 patients (23 men, 12 women; mean age, 50 years; range, 21-83 years) with acute necrotizing pancreatitis refractory to standard medical care who underwent CT-guided percutaneous catheter drainage with 12- to 22-French catheters. Experiences with two subgroups were compared. One group consisted of 22 patients, 10 with multisystem organ failure, who presented with sterile necrosis (median Atlanta score, 1.3; range, 0-3). The other group consisted of 13 patients, one with multisystem organ failure, who presented with infected necrosis (median Atlanta score, 0.4; range, 0-3). Differences between the group with sterile and the group with infected necrosis were analyzed with the Fisher-Holton exact and Mann-Whitney U tests. RESULTS Among 35 patients, 17 (49%) were treated successfully with CT-guided percutaneous catheter drainage alone. The effectiveness of CT-guided percutaneous catheter drainage in patients with sterile necrosis (11/22, 50%) was not significantly different from that of drainage in patients with infected necrosis (6/13, 46%). Among 11 patients with multisystem organ failure (10 with sterile necrosis, one with infected necrosis), only four (36%) were treated successfully with CT-guided percutaneous catheter drainage alone; five patients (45%) died. Among 24 patients without multisystem organ failure, 13 (54%) were treated successfully with CT-guided percutaneous catheter drainage alone; one patient died. CONCLUSION In our experience, primary CT-guided percutaneous catheter drainage was successful for approximately one half of the patients with acute necrotizing pancreatitis. The presence of multisystem organ failure appears to be a more important indicator of outcome than does the presence of infection.

Diffusion-Weighted MR Imaging in the Evaluation of Pancreatic Exocrine Function Before and After Secretin Stimulation

OBJECTIVES: To evaluate diffusion weighted MR imaging before and after secretin stimulation in the assessment of pancreatic exocrine function in the setting of chronic pancreatitis.METHODS: Nine patients with severe chronic pancreatitis and sixteen patients without chronic pancreatitis but with a history of chronic alcohol consumption were enrolled in the chronic pancreatitis and risk groups, respectively. Thirty-eight patients without any pancreatic disease or history of alcohol consumption were included in the control group. Diffusion weighted images were obtained before and after secretin administration in all patients. The peak ADC values and times were determined and intergroup differences were compared. A receiver operating characteristic curve (ROC) was used to identify the cutoff values of the peak ADC times for discrimination of control group from risk and chronic pancreatitis groups.RESULTS: In the control group, a peak increase in ADC value of 57–120% (median: 75%) was observed between 90 s and 4 min (median: 2 min) after administration of secretin (Pattern 1). In the risk group, in 13 patients, a peak increase of 52–150% was observed between 4 and 8 min (median: 7 min; Pattern 2). Peak times were significantly longer in risk group (p < 0.01). In three patients in the risk group, and in all patients in the chronic pancretitis group, no ADC peak was observed within 10 min following secretin administration (Pattern 3). Using a peak time of 4 min as the cut-off value, a sensitivity of 100% and specificity of 94.7% were achieved in discriminating the control group from the combined risk and chronic pancreatitis groups.CONCLUSION: Diffusion-weighted MR imaging before and after secretin administration could yield clinically useful information for detecting pathophysiologic alterations in the setting of chronic pancreatitis.

MDCT of Pancreatic Adenocarcinoma: Optimal Imaging Phases and Multiplanar Reformatted Imaging

OBJECTIVE The objective of our study was to evaluate the individual contributions of arterial, pancreatic parenchymal, and portal venous phase (PVP) images and the utility of coronal and sagittal multiplanar reformatted (MPR) images in the assessment of pancreatic adenocarcinoma using triple-phase MDCT. MATERIALS AND METHODS Thirty-one patients with and 35 patients without pancreatic adenocarcinoma underwent triple-phase MDCT. Three radiologists independently attempted to detect pancreatic adenocarcinoma and assess local extension using the MDCT images in five sessions. The first three sessions involved sets of images obtained in arterial phase, pancreatic parenchymal phase, and PVP separately and respectively. In the fourth session, a combination of axial images from all phases was evaluated. During the fifth session, radiologists had access to coronal and sagittal MPR images together with the axial images obtained in all phases. Results were compared with surgical findings using receiver operating characteristic (ROC) analysis and kappa statistics. RESULTS Regarding tumor detection, the image set composed of coronal and sagittal MPR images and of axial images obtained in all phases had a significantly higher value for the area under the ROC curve (A(Z), 0.98 +/- 0.01) than the other image sets and yielded the highest sensitivity (93.5%). The sensitivity of the arterial phase image set (80.6%) was significantly lower than that of all other image sets. Whereas the image set composed of coronal and sagittal MPR images and axial images obtained in all phases yielded the highest kappa values for all local extension factors evaluated, the image set composed of only arterial phase images yielded the lowest kappa values for almost all of the factors. CONCLUSION A combination of pancreatic parenchymal phase and PVP imaging is necessary and efficient for the assessment of pancreatic adenocarcinoma. The addition of coronal and sagittal MPR images increased the performance of MDCT, especially in the evaluation of local extension.

CT Features of Hepatic Venoocclusive Disease and Hepatic Graft-Versus-Host Disease in Patients After Hematopoietic Stem Cell Transplantation

OBJECTIVE We conducted this study to evaluate whether CT scans could be used to differentiate hepatic venoocclusive disease from hepatic graft-versus-host disease in patients treated with hematopoietic stem cell transplantation. SUBJECTS AND METHODS We retrospectively evaluated 18 patients (eight women, 10 men; mean age, 42.4 years) after hematopoietic stem cell transplantation with biopsy-proven hepatic venoocclusive disease (n = 5), hepatic graft-versus-host disease (n = 6), or both (n = 7). Two radiologists reviewed abdominal and pelvic CT scans for hepatomegaly (> 18 cm), splenomegaly (> 13 cm), size of main portal and right hepatic veins, presence of periportal edema, gallbladder wall edema, hydropic gallbladder, ascites, and small-bowel wall thickening. CT and histopathology findings were correlated using analysis of variance and Fisher-Free-man-Holton tests. RESULTS Ascites and periportal edema were present in all five patients with venoocclusive disease, but of six patients with graft-versus-host disease, ascites was seen in two (p < 0.05) and periportal edema in only one (p < 0.05). Small-bowel wall thickening was encountered in five patients with graft-versus-host disease and in none with venoocclusive disease (p < 0.05). The right hepatic vein diameter in patients with venoocclusive disease (mean, 0.27 cm) was significantly smaller than the right hepatic vein diameter in patients with graft-versus-host disease (mean, 0.87 cm; p < 0.05). CONCLUSION In patients treated with hematopoietic stem cell transplantation, CT findings of periportal edema, ascites, and a narrow right hepatic vein suggest venoocclusive disease rather than graft-versus-host disease. Small-bowel wall thickening suggests graft-versus-host disease.

Use of 3.0-T MR imaging for evaluation of the abdomen.

The most important advantage of 3.0-T magnetic resonance (MR) imaging systems is their increased signal-to-noise ratio (SNR) compared with 1.5-T systems. The higher SNR can be used to shorten acquisition time, achieve higher spatial resolution, or a combination of the two, thereby improving image quality and clinical diagnosis. In fact, 3.0-T MR imaging systems have already proved superior to 1.5-T systems in neuroradiologic and musculoskeletal applications. In the abdomen, 3.0-T MR imaging is uniquely beneficial for techniques such as enhanced and nonenhanced hepatic imaging, diffusion-weighted imaging, angiography, MR pancreatography, and colonography. Admittedly, 3.0-T abdominal imaging has important technical limitations, such as standing wave artifact, chemical shift artifact, susceptibility artifact, and safety issues such as increased energy deposition within the patients body. Furthermore, 3.0-T abdominal MR imaging is still in the early stages of development and requires substantial modifications of the pulse sequences and hardware components used for 1.5-T imaging. Nevertheless, the ability to obtain physiologic and functional information within reasonably short acquisition times with 3.0-T abdominal MR imaging bodies well for the future of this imaging technique.

Dynamic MR Defecography: Assessment of the Usefulness of the Defecation Phase

OBJECTIVE The purpose of this study was to assess the usefulness of the defecation phase during dynamic MR defecography. MATERIALS AND METHODS The images from 85 MR defecographic examinations (83 patients; age range, 20-88 years; mean, 52.7) were retrospectively reviewed in consensus by two observers. Images from each of four phases (rest, maximal sphincter contraction and squeezing, maximal straining, and defecation) were evaluated and scored independently with a modified previously published grading system. Features evaluated included the presence and degree of bladder, vaginal, and rectal descent and the presence and size of rectocele, enterocele, and intussusception. Statistical analysis was performed with a variety of tests. RESULTS Compared with images obtained in the other phases, defecation phase images helped in identification of additional cases of abnormal bladder descent in 43 examinations (50.6%), abnormal vaginal descent in 52 examinations (61.2%), and abnormal rectal descent in 11 examinations (12.9%). Similarly, only defecation phase images depicted previously undetected rectoceles 2 cm or larger in 31 examinations (36.5%), enteroceles in 34 examinations (40%), and intussusceptions in 22 examinations (25.9%). The number of additional cases of abnormalities identified on defecation phase images was significantly greater than the number identified on images obtained in the other phases (p < 0.005). The average total scores for the rest, squeeze, strain, and defecation phases were 1.4, 0.7, 2.3, and 6.6. The average total defecation phase score was significantly greater than the average total score in any of the other phases (p < 0.001). CONCLUSION During dynamic MR defecography, defecation phase imaging yields important additional information on the presence and degree of pelvic floor abnormalities and is therefore an essential component of MR defecographic examinations.

Sensitivity of Immediate and Delayed Gadolinium-Enhanced MRI After Injection of 0.5 M and 1.0 M Gadolinium Chelates for Detecting Multiple Sclerosis Lesions

OBJECTIVE The purpose of our study was to compare the efficacy of cranial MR images obtained immediately after, 5 minutes after, and 10 minutes after the injection of 0.5-mol/L (Magnevist) and 1.0-mol/L (Gadovist) gadolinium chelates in the detection of active multiple sclerosis (MS) lesions. MATERIALS AND METHODS Thirty patients with MS were examined with MRI first with 0.5-mol/L and then, after 24-48 hours, with 1.0-mol/L gadolinium chelates. T1-weighted spin-echo images with magnetization transfer were obtained immediately, 5 minutes, and 10 minutes after the injection of the contrast material. Three radiologists evaluated the gadolinium-enhanced T1-weighted images on a remote MR console (Advantage Windows) in six separate sessions and counted the number of enhancing lesions in consensus. RESULTS Significantly fewer enhancing lesions were seen on MR images immediately after the injection of 0.5- and 1.0-mol/L gadolinium chelates (n = 18 and n = 36, respectively; p < 0.05) than at 5 minutes (n = 32 and n = 54; p < 0.05) and 10 minutes (n = 34 and n =55; p < 0.05) after the injection (p < 0.05). Likewise, significantly fewer patients with at least one enhancing lesion after the injection of 0.5- and 1.0-mol/L gadolinium chelates (n = 10 and n = 16; p < 0.05) were found immediately after injection than were found 5 minutes (n = 18 and n = 24; p < 0.05) and 10 minutes (n = 18 and n = 24; p < 0.05) after injection (p < 0.01). CONCLUSION The use of 1.0-mol/L gadolinium chelate enables us to detect an increased number of enhancing lesions and patients with active disease. A delay of 5 minutes after the injection of the gadolinium chelate might be sufficient to detect active lesions in patients with MS.