Sandra Pauls

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.

Is a preoperative multidiagnostic approach to predict surgical resectability of periampullary tumors still effective

BACKGROUND Multimodality staging is recommended in patients with periampullary tumors to optimize preoperative determination of resectability. We investigated the potency of currently used diagnostic procedures in order to determine resectability. METHODS Ninety-five consecutive patients with periampullary tumors prehospitally staged resectable underwent preoperative diagnostic tests: helical-computed tomography (CT) with maximum intensity projection of arterial vessels (MIP), magnetic resonance imaging (MRI), magnetic resonance cholangiopancreaticography (MRCP), endoscopic ultrasonography (EUS), endoscopic retrograde cholangiopancreaticography (ERCP), digital subtraction angiography (DSA), and positron emission tomography (PET). Diagnoses were verified by surgery and histopathology. RESULTS In 45 patients with benign and 50 patients with malignant periampullary tumors sensitivity for tumor diagnosis was 89% to 96% in CT, MRI, EUS, and PET. Small tumors were best diagnosed by EUS (100%). Diagnosis of malignancy was made with 85% (EUS), 83% (CT), 82% (PET), and 72% (MRI) accuracy. Arterial vessel infiltration was best predicted by CT/MIP with an accuracy of 85%. For venous vessel infiltration MRI reached 85% accuracy. Accuracy rates for local nonresectability were 93% (EUS), 92% (MRI), and 90% (CT). Two and 4 of 8 patients with distant metastases were identified by CT and PET, respectively. The correct diagnosis of malignancy and determination of resectability was made by CT in 71% and by MRI in 70%. Biliary stenting reduced accuracy of CT diagnosis of malignancy from 88% to 73%. CONCLUSIONS CT obtained before stenting was the single most useful test, providing correct diagnosis in 88% and resectability in 71% of patients. If no tumor is depicted in CT, EUS should be added. Uncertain venous vessel infiltration can be verified by MRI or EUS. Angiography should no longer be a routine diagnostic procedure. Equivocal tumors or possible metastasis may be further examined with PET.

Contrast-enhanced wideband harmonic imaging ultrasound (SonoVue®): A new technique for quantifying bowel wall vascularity in Crohn's disease

Objective. To assess the possibility of quantitative determination of bowel wall vascularity using contrast-enhanced (SonoVue®) wideband harmonic imaging ultrasound and the HDI-Lab software in patients with Crohns disease. Material and methods. Twenty-one patients (13 F, 8 M, average age 33.8±12.7 years, range 21–60 years) with histologically confirmed Crohns disease and bowel wall thickness ≥5 mm were recruited for the study. All ultrasound examinations were performed using a Philips HDI 5000 scanner. Bowel wall vascularity was determined at the site of maximum bowel wall thickness at baseline and at 30, 60, 90 and 120 s following application of the contrast enhancer SonoVue (1.2 ml) using the HDI-Lab software. Results. The mean length of bowel segments exhibiting increased wall thickness was 122.3 mm (range: 23–350±74.7 mm), with a mean wall thickness of 7.6±1.2 mm. Onset of echo enhancement secondary to contrast medium application was observed after an average 13.4 s (range 7–19±4.2 s). Echo intensity corresponding to maximum vascularity was measured 30 s after application of contrast medium. Maximum average contrast medium uptake was 217.5% (range 118–466±100.1%). Conclusions. It is possible to quantify bowel wall vascularity accurately in patients with Crohns disease using contrast-enhanced pulse inversion ultrasound (low-MI).

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.

Clinical value of 18F-fluorodihydroxyphenylalanine positron emission tomography/computed tomography (18F-DOPA PET/CT) for detecting pheochromocytoma

PurposeIn detecting pheochromocytoma (PHEO), positron emission tomography (PET) with the radiolabelled amine precursor 18F-fluorodihydroxyphenylalanine (18F-DOPA) offers excellent specificity, while computed tomography (CT) provides high sensitivity and ability to localize lesions; therefore, the combination of these modalities could be advantageous in this setting. The aim of this study was to investigate whether combined 18F-DOPA PET/CT more accurately detects and localizes PHEO lesions than does each modality alone.Methods18F-DOPA PET, CT and 18F-DOPA PET/CT images of 25 consecutive patients undergoing diagnostic scanning of suspected sporadic or multiple endocrine neoplasia type 2 syndrome-associated PHEO were reviewed retrospectively in randomized sequence. Two blinded observers scored the images regarding the likelihood of PHEO being present and localizable. Results were correlated with subsequent clinical history and, when available, histology.ResultsOf the 19 lesions detected by all three modalities, PET identified each as positive for PHEO, but was unable to definitively localize 15 of 19 (79%). CT could definitively localize all 19 lesions, but could not definitively diagnose or exclude PHEO in 18 of 19 (95%) lesions. Furthermore, CT falsely identified as negative for PHEO one lesion which was judged to be positive for this tumor by both PET and PET/CT. Only in PET/CT scans were all 19 lesions accurately characterized and localized. On a per-patient basis, the sensitivity of 18F-DOPA PET/CT for PHEO was 100% and the specificity 88%, with a 100% positive predictive value and an 88% negative predictive value.Conclusion18F-DOPA PET/CT more accurately diagnoses and localizes adrenal and extra-adrenal masses suspicious for PHEO than do 18F-DOPA PET or CT alone.

Relevant imaging findings of cerebral aspergillosis on MRI: a retrospective case‐based study in immunocompromised patients

The aim of the study was to assess neuroimaging patterns of cerebral aspergillosis with magnetic resonance imaging (1.5 T). The clinical and imaging data of nine patients were reviewed. Patients were included in the study if the diagnosis of aspergillosis was confirmed by either biopsy, autopsy, aspergillus antigen determination and/or neuroradiological and clinical response to specific treatment. Four patients had single or multiple abscesses presenting as ring‐enhancing lesions on T1‐weighted images, hypointensity of the ring on T2‐weighted MR images and low to high signal intensity on diffusion‐weighted imaging. Four patients had single or multiple infarctions affecting all compartments of the brain with hyperintensities on T2‐weighted images in three of four patients, irregular parenchymal contrast enhancement in all patients and hemorrhagic transformation of the infarcted parenchyma in one patient. Diffusion‐weighted images were positive in all ischemic areas. One patient with paranasal sinusitis developed a mycotic aneurysm of the internal carotid artery. Cerebral aspergillosis presents three principal neuroimaging findings: areas consistent with infarction; ring lesions consistent with abscess formation following infarction; and dural or vascular infiltration originating from paranasal sinusitis or orbital infiltration. Recognition of these patterns in cerebral aspergillosis may lead to more timely and effective diagnosis and treatment.

Prospective comparison of endoscopic ultrasound and endoscopic retrograde cholangiopancreatography in the preoperative assessment of masses in the pancreatic head.

Aims: To compare the diagnostic value of endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP) in the differentiation of malignant from benign masses in the pancreatic head. Methods: Within 14 months 95 prospective patients with masses in the pancreatic head were assigned for preoperative EUS and ERCP. Both procedures were performed and recorded according to a standardized protocol. Based on intraoperative findings and histology, 50 patients (53%) suffered from malignant and 45 patients (47%) from benign (inflammatory) tumors. Results: Success rates were 96% for EUS and 95% for ERCP. The overall results for EUS and ERCP to predict malignant masses were, respectively: sensitivity 78 and 81%, specificity 93 and 88%, positive predictive value 93 and 89%, negative predictive value 78 and 80%, and diagnostic accuracy 85 and 84%. When EUS and ERCP were taken together, the sensitivity was 92% (specificity 85%), but the diagnostic accuracy (89%) was not significantly enhanced. The results for EUS to diagnose lymph node metastases preoperatively were: sensitivity 55%, specificity 91%, positive predictive value 69%, negative predictive value 84%, and accuracy 81%. Conclusions: EUS and ERCP have similar diagnostic accuracies to separate malignant from benign masses in the pancreatic head. Combination of both procedures is not superior to the use of one modality alone. Abnormal lymph nodes visualized on EUS in patients with inflammatory masses in the pancreatic head due to chronic pancreatitis should be interpreted cautiously.

Assessment of COPD severity by computed tomography: correlation with lung functional testing

CT scans of 474 patients with suspected chronic obstructive pulmonary disease (COPD) were retrospectively evaluated by automated software. There was a correlation between the total lung capacity (TLC) and the total lung volume (TLV) (r=.675, P<.001), between the TLC and the total emphysema volume (r=.571, P<.001), as well as between the TLC and the emphysema index (r=.532, P<.001), respectively. The correlation between the TLC and the TLV was dependent on the COPD severity according to the Global Initiative for Chronic Obstructive Lung Disease classification (chi(2)=6.3079, P=.043). The TLC allows a prediction of clinical illness severity.

CT-guided lung biopsy: incidence of pneumothorax after instillation of NaCl into the biopsy track

This study was conducted to evaluate whether instillation of NaCl 0.9% solution into the biopsy track reduces the incidence of pneumothoraces after CT-guided lung biopsy. A total of 140 consecutive patients with pulmonary lesions were included in this prospective study. All patients were alternatingly assigned to one of two groups: group A in whom the puncture access was sealed by instillation of NaCl 0.9% solution during extraction of the guide needle (n = 70) or group B for whom no sealing was performed (n = 70). CT-guided biopsy was performed with a 18-G coaxial system. Localization of lesion (pleural, peripheral, central), lesion size, needle-pleural angle, rate of pneumothorax and alveolar hemorrhage were evaluated. In group A, the incidence of pneumothorax was lower compared to group B (8%, 6/70 patients vs. 34%, 24/70 patients; P < 0.001). All pneumothoraces occurred directly post punctionem after extraction of the guide needle. One patient in group A and eight patients in group B developed large pneumothoraces requiring chest tube placement (P = 0.01). The frequency of pneumothorax was independent of other variables. After CT-guided biopsy, instillation of NaCl 0.9% solution into the puncture access during extraction of the needle significantly reduces the incidence of pneumothorax.

Use of integrated FDG-PET/CT in sarcoidosis

We studied five patients with mediastinal lymph node enlargement suggestive of malignant lymphoma, lung cancer, or sarcoidosis. Integrated [(18)F]fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) was performed on all patients. Sarcoidosis can be a pitfall in PET/CT imaging, which may lead to false-positive results of malignancy. Increased FDG uptake in mediastinal lymph nodes is often comparable with malignant lymphoma or lymph node metastases. Histological confirmation of the lesions should be mandatory, except for patients in whom sarcoidosis can be accurately confirmed by other diagnostic methods.