Baris Bakir

Diffusion weighted MR imaging of pancreatic islet cell tumors

PURPOSE The aim of our study is to demonstrate the feasibility of body diffusion weighted (DW) MR imaging in the evaluation of pancreatic islet cell tumors (ICTs) and to define apparent diffusion coefficient (ADC) values for these tumors. MATERIALS AND METHODS 12 normal volunteers and 12 patients with histopathologically proven pancreatic ICT by surgery were included in the study. DW MR images were obtained by a body-phased array coil using a multisection single-shot echo planar sequence on the axial plane without breath holding. In addition, the routine abdominal imaging protocol for pancreas was applied in the patient group. We measured the ADC value within the normal pancreas in control group, pancreatic ICT, and surrounding pancreas parenchyma. Mann-Whitney U-test has been used to compare ADC values between tumoral tissues and normal pancreatic tissues of the volunteers. Wilcoxon Signed Ranks Test was preferred to compare ADC values between tumoral tissues and surrounding pancreatic parenchyma of the patients. RESULTS In 11 patients out of 12, conventional MR sequences were able to demonstrate ICTs succesfully. In 1 patient an indistinct suspicious lesion was noted at the pancreatic tail. DW sequence was able to demonstrate the lesions in all of the 12 patients. On the DW images, all ICTs demonstrated high signal intensity relative to the surrounding pancreatic parenchyma. The mean and standard deviations of the ADC values (x10(-3)mm(2)/s) were as follows: ICT (n=12), 1.51+/-0.35 (0.91-2.11), surrounding parenchyma (n=11) 0.76+/-0.15 (0.51-1.01) and normal pancreas in normal volunteers (n=12), 0.80+/-0.06 (0.72-0.90). ADC values of the ICT were significantly higher compared with those of surrounding parenchyma (p<0.01) and normal pancreas (p<0.001). CONCLUSION DW MR imaging does not appear to provide significant contribution to routine MR imaging protocol in the evaluation of pancreatic islet cell tumors. But it can be added to MR imaging protocol to detect the lesion in a limited number of patients with clinical suspicion for pancreatic ICT with negative or suspicious imaging findings.

Diagnostic value of PET/CT is similar to that of conventional MRI and even better for detecting small peritoneal implants in patients with recurrent ovarian cancer.

ObjectiveThe aim of this study was to evaluate the diagnostic value of 2-(fluorine-18)-fluoro-2-deoxy-D-glucose (18F-FDG) PET/CT in comparison with MRI for the detection of recurrent ovarian cancer. MethodsForty-seven patients with suspected ovarian cancer recurrence after total ablative or cytoreductive surgery, as well as neoadjuvant or adjuvant chemotherapy, who had undergone 18F-FDG PET/CT imaging were recruited for the present study. All patients also underwent MRI within a month of 18F-FDG PET/CT for the same purpose. Recurrent cancer in the abdomen and pelvis was evaluated in each of the 47 patients and classified as either distant metastasis or local pelvic recurrence involving the vaginal stump, peritoneal implants, supradiaphragmatic region, and/or abdominal and pelvic lymph nodes. Special attention was paid to peritoneal implants. These were divided into five groups according to size of the implants: less than 0.5 cm (group 1), 0.5–1 cm (group 2), 1–2 cm (group 3), 2–3 cm (group 4), and larger than 3 cm (group 5). PET/CT findings were compared with abdominopelvic MR findings. Statistical analysis was carried out using the Wilcoxon signed rank test. ResultsThirty-nine of 47 patients were found to have recurrent ovarian cancer. Both PET/CT and MRI were negative for recurrence in six patients. Overall sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of PET/CT were 97.5, 100, 100, 87.5, and 97.8%, respectively, whereas those of MRI were 95, 85.7, 97.4, 75, and 93.6%, respectively. For the peritoneal implants in groups 2 and 3, the sensitivity, negative predictive value, and diagnostic accuracy values of PET/CT were significantly better than those of MRI (P<0.05). ConclusionThe present study revealed that PET/CT is similar to conventional MRI for the detection of recurrent ovarian cancer. PET/CT has greater accuracy in the detection of small-to-medium-sized (<2 cm) peritoneal implants compared with MRI. This may affect surgical decision making.

Role of Diffusion-weighted MR Imaging in the Differentiation of Benign Retroperitoneal Fibrosis from Malignant Neoplasm: Preliminary Study

PURPOSE To evaluate diffusion-weighted imaging (DWI) features and signal intensity values at T2-weighted magnetic resonance (MR) imaging for differential diagnosis of benign retroperitoneal fibrosis (RPF) and plaque-like retroperitoneal malignant neoplasms. MATERIALS AND METHODS Institutional review board approval and informed consent were obtained for this retrospective study. Fifty-one patients with plaque-like confluent retroperitoneal soft-tissue masses were divided into three groups: group I, 25 patients with malignant RPF and retroperitoneal malignant neoplasm; group II, 16 patients with chronic RPF; and group III, 10 patients with active RPF. On T1-weighted (unenhanced and contrast material-enhanced), T2-weighted, and DWI (b = 1000 sec/mm(2)) images, apparent diffusion coefficient (ADC) values and quotients of postcontrast signal intensities between lesions and psoas muscle were evaluated. The χ(2) test was used to compare categorical values; one-way analysis of variance and Kruskal-Wallis tests were used to compare groups. RESULTS Overall sensitivity, specificity, and positive and negative predictive values of DWI findings were 92% (23 of 25 patients), 62% (16 of 26 patients), 70% (23 of 33 patients), and 89% (16 of 18 patients), respectively. Mean ADC values were 0.79 ± 0.19 in group I, 1.43 ± 0.16 in group II, and 0.91 ± 0.14 in group III. When comparing values, differences between groups I and II (ADC values, P < .0001; DWI quotients, P < .0001; postcontrast quotients, P = .001) and groups II and III (ADC values, P < .0001; DWI quotients, P = .016; postcontrast quotients, P = .04) were significant. There was no significant difference between groups I and III or between the three groups when T2-weighted values were compared. CONCLUSION ADC of chronic RPF was higher than that for active RPF or malignant RPF and retroperitoneal malignant neoplasm. DWI can contribute to differential diagnosis of chronic RPF and malignant neoplasms with RPF morphology. Lesions in the malignant group and active RPF group had similar enhancement patterns, while those in the chronic RPF group demonstrated less enhancement. Signal intensity values on T2-weighted images were not useful for differentiating these conditions.

CT and MR characteristics of hibernoma: six cases

PURPOSE The purpose of this study was to describe the computed tomography (CT) and magnetic resonance (MR) imaging findings of hibernoma. MATERIALS AND METHODS We retrospectively evaluated imaging findings of CT and MR examinations of six patients (three men and three woman, aged 27-48 years) with histopathological diagnosis of hibernoma. RESULTS On CT examination, the lesions were slightly hyperdense, and on T1- and T2-weighted MR images, they were isointense or slightly hypointense compared to the subcutaneous fat. All of these lesions showed contrast enhancement and one out of the six lesions had internal linear septations. CONCLUSION Hibernoma has a wide spectrum of CT and MR imaging findings, which should be considered in differential diagnosis, especially with other lipomatous lesions.

Semantic Description of Liver CT Images: An Ontological Approach

Radiologists inspect CT scans and record their observations in reports to communicate with physicians. These reports may suffer from ambiguous language and inconsistencies resulting from subjective reporting styles, which present challenges in interpretation. Standardization efforts, such as the lexicon RadLex for radiology terms, aim to address this issue by developing standard vocabularies. While such vocabularies handle consistent annotation, they fall short in sufficiently processing reports for intelligent applications. To support such applications, the semantics of the concepts as well as their relationships must be modeled, for which, ontologies are effective. They enable the software to make inferences beyond what is present in the reports. This paper presents the open-source ontology ONLIRA (Ontology of the Liver for Radiology), which is developed to support such intelligent applications, such as identifying and ranking similar liver patient cases. ONLIRA is introduced in terms of its concepts, properties, and relations. Examples of real liver patient cases are provided for illustration purposes. The ontology is evaluated in terms of its ability to express real liver patient cases and address semantic queries.

Hepatic adenomatosis may mimic metastatic lesions of liver with 18F-FDG PET/CT.

Hepatic adenomatosis is an uncommon benign neoplasm, with the presence of multiple adenomas (generally more than 4) within the liver. A 52-year-old woman presented with multiple (>10) solid liver lesions detected with abdominal ultrasonography and verified with magnetic resonance imaging (MRI). Subsequently, F-18 FDG PET/CT demonstrated increased uptake in these lesions. Histology revealed hepatic adenomatosis. F-18 FDG PET/CT cannot reliably differentiate hepatic adenomas from malignant processes on the basis of uptake.

MR Colonography after Oral Administration of Polyethylene Glycol–Electrolyte Solution

This prospective study was approved by the local institutional ethics committee, and written informed consent was obtained from all patients. The aim of this study was to determine whether the oral administration of a polyethylene glycol (PEG)-electrolyte solution induces adequate luminal distention for magnetic resonance (MR) colonography to be performed and to assess patient acceptance of this procedure. Fifty-five patients (26 women, 29 men; mean age, 60.5 years +/- 14 [standard deviation]; age range, 40-75 years) who were referred for optical colonoscopy (OC) owing to symptoms and findings that included rectal bleeding, altered bowel habits, and positive fecal occult blood test results participated in this study. Standard bowel preparation was performed 1 day before the procedure. MR colonography was performed and followed by OC on the same day. Before undergoing MR colonography, the patients received 2.0-2.5 L of the PEG-electrolyte solution orally. Adequate distention of all colonic segments was achieved in 50-53 (91%-96%) of patients imaged in the supine position and in 51-53 (93%-96%) of patients imaged in the prone position. Oral administration of the solution yielded uniform luminal darkening and sufficient colonic distention for MR colonography in 91%-96% of patients.

Vesicouterine fistula presenting with urinary incontinence 30 years after primary Cesarean: Case report and review of the literature.

A vesicouterine fistula is an abnormal communication between the bladder and the uterus. The most common cause is lower segment Cesarean section. Conservative treatment may be applied in some cases, but surgery is the definitive treatment. We present a 55-year-old woman with vesicouterine fistula after primary Cesarean section; she presented with urinary incontinence 30 years later. Methylene blue dye test was performed and drainage of urine dyed with methylene blue through the uterine cervix was observed. Diagnosis was confirmed with magnetic resonance imaging. Total abdominal hysterectomy and bilateral oophorectomy was performed and the bladder wall was sutured in a double layer with 2/0 polyglycolic suture. No complications developed and the patient did not suffer from any urinary incontinence afterwards. Vesicouterine fistula should be suspected in cases presenting with urinary incontinence even years after Cesarean section; diagnostic tests and, if necessary, appropriate surgery should be performed.

Congenital Portal Vein Aneurysm Associated with Peliosis Hepatis and Intestinal Lymphangiectasia

Portal vein aneurisym (PVA), peliosis hepatis (PH) and intestinal lymphangiectasia (IL) all are very uncommon entities. Herein, we presented a unique patient with these three rare entities who was admitted to our hospital because of portal hypertensive ascites rich in protein and lymphocyte. PVA was extrahepatic and associated with coronary vein aneurysm. Peliosis hepatis was of microscopic form. Lymphangiectasia was present in peritoneum and small intestine. Diagnoses of these rare entities were made by imaging techniques and histopathological findings. Patient also had hydronephrosis caused by ureteropelvic junction narrowing. Best of our knowledge, there is no such a case reported previously with the association of PVA, PH and IL. Therefore, we propose PVAPHIL syndrome to define this novel association.

Role of diffusion weighted MRI in the differential diagnosis of endometrial cancer, polyp, hyperplasia, and physiological thickening

Our purpose was to evaluate the role of diffusion-weighted imaging (DWI) in the diagnosis of various common pathologies of the uterine cavity, by comparing them with contrast-enhanced MRI findings. One hundred sixty-four patients with lesions in endometrial cavity were included in the study. The patients were grouped in four (one malignant and three benign groups). We have observed that the differences of the apparent diffusion coefficient, b1000q, and Cq values between various common benign and malignant lesions were statistically significant (P<.001). However, the differences of the values between benign groups were not statistically significant (P>.05). Alternatively, endometrial polyp groups signal intensity on DWI was different than the other groups.