Markus S. Juchems

Pitfalls in Abdominal Diffusion-Weighted Imaging: How Predictive is Restricted Water Diffusion for Malignancy

OBJECTIVE As diffusion-weighted imaging is increasingly implemented into routine protocols of abdominal MRI, abnormal findings in expected and unexpected locations become more common. The aim of our retrospective study was to investigate the specificity of restricted diffusion in differentiation of benign from malignant abdominal disease. MATERIALS AND METHODS Two hundred thirty consecutively registered patients underwent abdominal MRI including diffusion-weighted imaging (single-shot spin-echo echo-planar sequence) with b values of 0, 150, 500, and 1,000 s/mm(2). Lesions were detected by two blinded readers using only the images with a b value of 1,000 s/mm(2), and representative apparent diffusion coefficients were measured. Lymph nodes were not documented. RESULTS Fifty-two of the 230 patients had a total of 55 lesions with restricted diffusion (23.9%). The mean apparent diffusion coefficient was 809 mm(2)/s. Forty-three lesions (78.2%) were malignant. The 12 benign lesions were liver hemangioma, liver adenoma, autoimmune pancreatitis, pancreatic teratoma, two abscesses, three cases of inflammatory bowel wall thickening due to Crohns disease, Bartholin cyst, hemorrhagic ovarian cyst, and renal Rosai-Dorfman disease. CONCLUSION Restricted diffusion is generally considered to be associated with malignant tumors because of the high cellularity of these tumors. However, in interpretation of diffusion-weighted images, it should be kept in mind that a number of benign lesions, as many as 22% in our cohort, can exhibit restricted diffusion on images with high b values, thus mimicking malignant lesions.

Diffusion-weighted MR imaging in comparison to integrated [18F]-FDG PET/CT for N-staging in patients with lung cancer

PURPOSE The purpose of this study was to prospectively determine the diagnostic accuracy of diffusion-weighted imaging (DWI) using MRI in the staging of thoracic lymph nodes in patients with lung cancer, and to compare the performance to that of PET/CT. PATIENTS AND METHOD 20 consecutive patients (pts) with histologically proven lung cancer were included in this study. In all pts FDG-PET/CT was routinely performed to stage lung carcinoma. Additionally, MRI (1.5T) was performed including native T1w, T1w post contrast medium, T2w, and DWI sequences. Regarding the N stage based on the results of the PET/CT there were 5 patients with N0, 3 patients with N1, 5 patients with N2 and 7 patients with N3. Image analysis was performed by two radiologists (R1 and R2), respectively. The reviewers had to chose between 1 (at least one lymph node within a station is malignant) or 0 (no lymph nodes suspicious for malignancy). First the T1 post contrast sequence was analyzed. In a second step the DWI sequence (b=800) was analyzed. Both steps were performed in a blinded fashion. RESULTS MR imaging with or without DWI only agreed with the results of the PET/CT regarding the N stage in 80% of the patients-15% were understaged and 5% overstaged. There was excellent interobserver agreement; the N-staging result only differed in 1 patient for DWI, resulting in correlation coefficients of 0.98 for DWI and 1.0 for MRI. Compared to PET-CT MRI overstaged one and understaged 4 patients, while DWI overstaged one and understaged 3 patients. This resulted in correlation coefficients of 0.814 (R1 and R2) for MRI and 0.815 (R1) and 0.804 (R2) for DWI. Regarding the ADC values there were no significant differences between ipsilateral hilar (1.03 mm(2)/s ± 0.13), subcarinal (0.96 mm(2)/s±0.24), ipsilateral mediastinal (1.0mm(2)/s ± 0.18), contralateral mediastinal (0.93 mm(2)/s ± 0.23) and supraclavicular (0.9 mm(2)/s ± 0.23) lymph nodes. CONCLUSION Diffusion-weighted imaging does not show a clear advantage over conventional MR protocols in the N-staging of lung cancer. MRI with or without DWI shows a moderately correlation with PET/CT with a tendency for understaging.

Coronary plaque imaging with 256-slice multidetector computed tomography: interobserver variability of volumetric lesion parameters with semiautomatic plaque analysis software

The purpose of this study was to evaluate the potential clinical value of coronary plaque imaging with a new generation CT scanner and the interobserver variability of coronary plaque assessment with a new semiautomatic plaque analysis application. Thirty-five isolated plaques of the left anterior descending coronary artery from 35 patients were evaluated with a new semiautomatic plaque analysis application. All patients were scanned with a 256-slice MDCT scanner (Brilliance iCT, Philips Healthcare, Cleveland OH, USA). Two independent observers evaluated lesion volume, maximum plaque burden, lesion CT number mean and standard deviation, and relative lesion composition. We found 10 noncalcified, 16 mixed, and 9 calcified lesions in our study cohort. Relative interobserver bias and variability for lesion volume were −37%, −13%, −49%, −44% and 28%, 16%, 37%, and 90% for all, noncalcified, mixed, and calcified lesions, respectively. Absolute interobserver bias and variability for relative lesion composition were 1.2%, 0.5%, 1.5%, 1.3% and 3.3%, 4.5%, 7.0%, and 4.4% for all, noncalcified, mixed, and calcified lesions, respectively. While mixed and calcified lesions demonstrated a high degree of lesion volume interobserver variability, noncalcified lesions had a lower degree of lesion volume interobserver variability. In addition, relative noncalcified lesion composition had a very low interobserver variability. Therefore, there may a role for MDCT in serial noncalcified plaque assessment with semiautomatic analysis software.

A Retrospective Evaluation of Patient Acceptance of Computed Tomography Colonography (“Virtual Colonoscopy”) in Comparison with Conventional Colonoscopy in an Average Risk Screening Population

Purpose: To evaluate patient acceptance of computed tomography (CT) colonography compared with conventional colonoscopy by means of a self-assessed questionnaire. Material and Methods: Four-hundred-and-one patients with valid address information from our patient collective were preselected. Patient acceptance was evaluated retrospectively using a self-assessed questionnaire. The patients underwent CT colonography in our institution using 4× or 16× multi-detector row (MDR) CT. Two-hundred-and-forty-six patients returned a completed questionnaire, 157 of these indicating that they had undergone both virtual and conventional colonoscopy. Results: One-hundred-and-twenty (76.4%) of the 157 patients would undergo another CT colonography if necessary, while only 14 patients would not. One-hundred-and-sixteen (73.9%) patients favored the actual examination procedure of CT colonography (P<0.0001), while only 6.4% preferred the conventional method. Preparation prior to CT colonography was experienced as more convenient than preparation prior to conventional colonoscopy (52.2% versus 14%). Conclusion: CT colonography was preferred in terms of both preparation and the actual procedure itself.

Sensitive and Specific Immunohistochemical Diagnosis of Human Alveolar Echinococcosis with the Monoclonal Antibody Em2G11

Background Alveolar echinococcosis (AE) is caused by the metacestode stage of Echinococcus multilocularis. Differential diagnosis with cystic echinococcosis (CE) caused by E. granulosus and AE is challenging. We aimed at improving diagnosis of AE on paraffin sections of infected human tissue by immunohistochemical testing of a specific antibody. Methodology/Principal Findings We have analysed 96 paraffin archived specimens, including 6 cutting needle biopsies and 3 fine needle aspirates, from patients with suspected AE or CE with the monoclonal antibody (mAb) Em2G11 specific for the Em2 antigen of E. multilocularis metacestodes. In human tissue, staining with mAb Em2G11 is highly specific for E. multilocularis metacestodes while no staining is detected in CE lesions. In addition, the antibody detects small particles of E. multilocularis (spems) of less than 1 µm outside the main lesion in necrotic tissue, liver sinusoids and lymphatic tissue most probably caused by shedding of parasitic material. The conventional histological diagnosis based on haematoxylin and eosin and PAS stainings were in accordance with the immunohistological diagnosis using mAb Em2G11 in 90 of 96 samples. In 6 samples conventional subtype diagnosis of echinococcosis had to be adjusted when revised by immunohistology with mAb Em2G11. Conclusions/Significance Immunohistochemistry with the mAb Em2G11 is a new, highly specific and sensitive diagnostic tool for AE. The staining of small particles of E. multilocularis (spems) outside the main lesion including immunocompetent tissue, such as lymph nodes, suggests a systemic effect on the host.

CT colonography: an update

Computed tomographic (CT) colonography (CTC)—also known as “virtual colonoscopy”—was first described more than a decade ago. As advancements in scanner technology and three-dimensional (3D) postprocessing helped develop this method to mature into a potential option in screening for colorectal cancer, the fundamentals of the examination remained the same. It is a minimally invasive, CT-based procedure that simulates conventional colonoscopy using 2D and 3D computerized reconstructions. The primary aim of CTC is the detection of colorectal polyps and carcinomas. However, studies reveal a wide performance variety in regard to polyp detection, especially for smaller polyps. This article reviews the available literature, discusses established indications as well as open issues and highlights potential future developments of CTC.

Dermoid cyst of the pancreas

Dear Editor: Dermoid cysts (cystic teratoma) are congenital developmental abnormalities of germ cell origin derived from any of the three germinal layers, e.g., ectoderm, entoderm, mesoderm. As true cysts, dermoid cysts are usually benign, welldifferentiated lesions. Along the pathway of ectodermal cell migration, they are commonly found in the ovary, testes, and retroperitoneum. The pancreas is extremely rare as a primary site. A 40-year-old Caucasian male presented with a short history of recurrent upper abdominal pain. The patient was in an excellent state of health with a body mass index of 24 kg/m2. Laboratory examination showed normal values except for increased gamma glutamyltransferase by 1.66fold (91 U/l; upper normal limit, 55 U/l) and carbohydrate antigen 19-9 (CA 19-9) by 1.94-fold (62 IU/ml; upper normal limit, 32 IU/ml). Abdominal ultrasound revealed an inhomogenic mass in the area of the pancreas allocated into the pancreas by subsequent endoscopic ultrasound. Magnetic resonance tomography showed a well-defined cystic tumor measuring 64×49×38 mm arising at the border of the pancreatic head to body with a central necrosis. The duodenum and the stomach were displaced ventrally/laterally. The pancreatic main duct was not altered. No signs of irresectability were found. Gastric and duodenal infiltration was excluded by esophagogastroduodenoscopy. There were no signs of metastatic spread. A cytologic (fine-needle aspiration cytology (FNAC)) or histologic assessment before resection was not performed. A symptomatic tumor of more than 2 cm in size is associated with a high risk of malignancy. Therefore, primary surgery was performed. The cystic tumor was found to originate from the border of the pancreatic head and body protruding the major curvature of the stomach and the duodenal bulb and with contact to the portal vein on the backside. Meticulous mobilization finally allowed for pyloric preserving partial duodenopancreatectomy with a resection margin in the pancreas, 3 cm left of the vena mesenterica superior. The postoperative course was uneventful except for a self-limiting low-output pancreatic fistula treated conservatively. Macroscopically, the tumor consisted of an intact lobulated cyst, encapsulating yellow-brown pasty material. Cutting the surface of the tumor revealed a pasty sebaceous filling. On histological examination, the cyst wall was lined by mature stratified squamous epithelium, surrounded by lymphoid tissue containing germinal centers and sebaceous glands. In the lumen of the cyst, masses of keratinous debris were detected. In absence of any atypia, the final diagnosis was a dermoid cyst of the pancreas. In contrast to lympho-epithelial cysts, dermoid cysts are rarely found in the pancreatic tail and with only slightly more frequency in men than in women. There is no predominance of age as they present in all stages of life. This observation underscores the strictly benign nature of this pancreatic tumor without tendency of malign transformation. The majority of patients are symptomatic at the J. Scheele : J. Strasburg :M. Kornmann (*) :D. Henne-Bruns Clinic of General, Visceral, and Transplantion Surgery, University of Ulm, Steinhoevelstrasse 9, 89075 Ulm, Germany e-mail: marko.kornmann@uniklinik-ulm.de

Liver perfusion with dynamic multidetector-row computed tomography as an objective method to evaluate the efficacy of chemotherapy in patients with colorectal cancer.

A total of 24 liver metastases of colorectal cancer were evaluated by dynamic multiphasic CT. Under chemotherapy, follow-up examinations were performed every 3 months. The tumor marker CEA before vs. after chemotherapy correlated with the mean contrast enhancement within the margin of metastases. The total size of metastases correlated with the size of central necrosis as well as with the size of marginal contrast enhancement. CT is able to quantify perfusion and local activity of liver metastases to determine the efficacy of chemotherapy.

Strongyloides stercoralis: a rare cause of obstructive duodenal stenosis.

Background: Strongyloidiasis is a rare helminthic infection in Europe, and it may cause duodenal obstruction. Methods: We report a patient who was admitted to our Medical Department with nausea and repeated vomiting since 10 years until food intake became impossible. Subsequent investigations revealed a duodenal obstruction at the upper third of the duodenum, as well as enterocolitis of the terminal ileum with eosinophils dispersed throughout the mucosa. Since food intake was still not possible after treatment with a course of i.v. PPI and prokinetic applications, we decided to perform a resection of the upper duodenum with Y-Roux reconstruction. Results: The histopathological examination of the resected specimen revealed strongyloidiasis. Conclusion: Parasite infections such as strongyloidiasis represent a rare differential diagnosis of duodenal obstruction especially if patients originate from endemic regions.

Objective evaluation of vessel attenuation in multidetector-row computed tomographic pulmonary angiography using high-density contrast material for the detection of pulmonary embolism.

Objective: The purpose of this study was to analyze the pulmonary vessel enhancement obtainable using high-density contrast material and saline flushing with automated bolus tracking for multidetector-row computed tomographic (MDCT) pulmonary angiography in a routine clinical setting. Methods: Attenuation values of pulmonary vessels were retrospectively measured in 51 CT scans performed on a 40-channel MDCT for unselected emergency patients with clinically suspected pulmonary embolism. Results: Mean vascular attenuation measured 326.7 ± 104 Hounsfield units (HU) in the pulmonary trunk and 299.1 ± 102 HU in the left distal lower lobe artery. Mean vascular attenuation values in the distal lower lobe artery were equal or higher than 150 HU for 94.1% (48/51) of patients. Conclusions: In conclusion, the combination of high-density contrast media and saline flushing with automated bolus tracking on a fast CT scanner reliably results in a homogenously high attenuation of pulmonary vessels, allowing precise delineation of clots down to the subsegmental level in MDCT pulmonary angiography.