Abnormal language-related oscillatory responses in primary progressive aphasia.

Patients with Primary Progressive Aphasia (PPA) may react to linguistic stimuli differently than healthy controls, reflecting degeneration of language networks and engagement of compensatory mechanisms. We used magnetoencephalography (MEG) to evaluate oscillatory neural responses in sentence comprehension, in patients with PPA and age-matched controls. Participants viewed sentences containing semantically and syntactically anomalous words that evoke distinct oscillatory responses. For age-matched controls, semantic anomalies elicited left-lateralized 8-30 Hz power decreases distributed along ventral brain regions, whereas syntactic anomalies elicited bilateral power decreases in both ventral and dorsal regions. In comparison to controls, patients with PPA showed altered patterns of induced oscillations, characterized by delayed latencies and attenuated amplitude, which were correlated with linguistic impairment measured offline. The recruitment of right hemisphere temporo-parietal areas (also found in controls) was correlated with preserved semantic processing abilities, indicating that preserved neural activity in these regions was able to support successful semantic processing. In contrast, syntactic processing was more consistently impaired in PPA, regardless of neural activity patterns, suggesting that this domain of language is particularly vulnerable to the neuronal loss. In addition, we found that delayed peak latencies of oscillatory responses were associated with lower accuracy for detecting semantic anomalies, suggesting that language deficits observed in PPA may be linked to delayed or slowed information processing.

Multidisciplinary retroperitoneal and pelvic soft-tissue sarcoma case conferences: the added value that radiologists can provide.

Clinical Vignette: A 50-year-old woman presents to the emergency department with increasing abdominal pain. Abdominal computed tomography imaging reveals an expanded inferior vena cava-filling defect that is suspicious for a retroperitoneal sarcoma, possibly a primary leiomyosarcoma of the inferior vena cava. The surgery team discusses the case with the radiologist, and all agree that there are multiple challenges with obtaining a tissue diagnosis and determining resectability. Thus, it is decided that this patient should be discussed at a multidisciplinary case conference. In the present article, we feature a case-based scenario focusing on the role of the radiologist in this type of multidisciplinary team.

Assessing the utilization of functional imaging in multiparametric prostate MRI in routine clinical practice.

AIM: To evaluate the utilization of functional imaging tests in multiparametric (mp)-MRI of the prostate in routine practice and to assess whether education improves usage. MATERIALS AND METHODS: With research ethics board approval, 254 patients underwent mp-MRI [diffusion-weighted imaging (DWI) and dynamic contrast enhancement (DCE)] over a 1-year period at a single tertiary-care referral centre for prostate disease. All studies were reported by fellowship-trained abdominal radiologists. To determine to what extent parametric tests were used, radiology reports were searched for terms indicating usage of DWI/DCE and studies were reviewed to determine whether post-processing of DCE was performed. Midway through the study, an internal continuing medical education (CME) programme was instituted (consisting of lectures, electronic reading material, intra- and inter-departmental prostate rounds) and a standardized reporting template was introduced. Utilization of functional imaging was compared between radiologists by years of experience and by number of examinations interpreted, by study indication, and before and after CME. RESULTS: Overall, both DWI and DCE were used in 50.7% of examinations. DWI (67.3%) was more frequently used than DCE (56.3%). DCE contrast curves were generated in 33.5% of studies, and quantitative analysis was performed in only one patient. Use of parametric tests was higher after CME (60.6% versus 40.4%), p = 0.009. There was no correlation between the use of parametric tests and years of experience, (p = 0.94), and there was no association with the number of examinations interpreted (p = 0.19-0.97). There was no association between the use of parametric tests and study indication, (p = 0.16); however, contrast curves were produced more frequently in non-staging studies, (p = 0.027). CONCLUSION: Parametric tests were underutilized in routine practice. DWI was used more commonly than DCE. CME was associated with increased utilization of mp-MRI.

Ten uncommon and unusual variants of renal angiomyolipoma (AML): radiologic-pathologic correlation.

Classic (triphasic) renal angiomyolipoma (AML) is currently classified as a neoplasm of perivascular epithelioid cells. For diagnosis of AML, the use of thin-section non-contrast enhanced CT (NECT) improves diagnostic accuracy; however, identifying gross fat within a very small AML is challenging and often better performed with chemical-shift MRI. Although the presence of gross intra-tumoural fat is essentially diagnostic of AML; co-existing intra-tumoural fat and calcification may represent renal cell carcinoma (RCC). Differentiating AML from retroperitoneal sarcoma can be difficult when AML is large; the feeding vessel and claw signs are suggestive imaging findings. AML can haemorrhage, with intra-tumoural aneurysm size >5 mm a more specific predictor of future haemorrhage than tumor size >4 cm. Diagnosis of AML in the setting of acute haemorrhage is complex; comparison studies or follow-up imaging may be required. Not all AML contain gross fat and imaging features of AML without visible fat overlap with RCC; however, homogeneity, hyperdensity at NECT, low T2-weighted signal intensity and, microscopic fat are suggestive features. Patients with tuberous sclerosis often demonstrate a combination of classic and minimal fat AML, but are also at a slightly increased risk for RCC and should be imaged cautiously. Several rare pathological variants of AML exist including AML with epithelial cysts and epithelioid AML, which have distinct imaging characteristics. Classic AML, although benign, can be locally invasive and the rare epithelioid AML can be frankly malignant. The purpose of this review is to highlight the imaging manifestations of 10 uncommon and unusual variants of AML using pathological correlation.

Pitfalls of adrenal imaging with chemical shift MRI.

Chemical shift (CS) MRI of the adrenal glands exploits the different precessional frequencies of fat and water protons to differentiate the intracytoplasmic lipid-containing adrenal adenoma from other adrenal lesions. The purpose of this review is to illustrate both technical and interpretive pitfalls of adrenal imaging with CS MRI and emphasize the importance of adherence to strict technical specifications and errors that may occur when other imaging features and clinical factors are not incorporated into the diagnosis. When performed properly, the specificity of CS MRI for the diagnosis of adrenal adenoma is over 90%. Sampling the in-phase and opposed-phase echoes in the correct order and during the same breath-hold are essential requirements, and using the first echo pair is preferred, if possible. CS MRI characterizes more adrenal adenomas then unenhanced CT but may be non-diagnostic in a proportion of lipid-poor adenomas; CT washout studies may be able to diagnose these lipid-poor adenomas. Other primary and secondary adrenal tumours and supra-renal disease entities may contain lipid or gross fat and mimic adenoma or myelolipoma. Heterogeneity within an adrenal lesion that contains intracytoplasmic lipid could be due to myelolipoma, lipomatous metaplasia of adenoma, or collision tumour. Correlation with previous imaging, other imaging features, clinical history, and laboratory investigations can minimize interpretive errors.

Non-neoplastic hepatic vascular diseases: spectrum of CT and MRI appearances.

The unique dual blood supply of the liver makes it one of the common sites for various vascular neoplastic and non-neoplastic diseases. Increasing use of multiphase contrast-enhanced computed tomography (CT) and dynamic magnetic resonance imaging (MRI) has led to increased identification of numerous non-neoplastic vascular entities apart from already well-known neoplastic lesions. The objective of this review is to describe the causes and clinical features and to familiarize the reader with the key imaging features of various non-neoplastic vascular diseases affecting the liver. Non-neoplastic vascular diseases are classified broadly as those affecting the hepatic veins, portal veins, hepatic artery, intrahepatic shunts, and other miscellaneous conditions.

Low-Radiation-Dose Modified Small Bowel CT for Evaluation of Recurrent Crohn's Disease.

Crohn's disease affects any part of the GI tract, commonly the terminal ileum. To decrease radiation exposure we developed a low-radiation-dose unenhanced CT (modified small Bowel CT, MBCT) to evaluate the small bowel using hyperdense oral contrast. Technique. MBCT was investigated in patients with pathologically proven Crohn's disease presenting with new symptoms from recurrent inflammation or stricture. After ethics board approval, 98 consecutive patients were retrospectively evaluated. Kappa values from two independent reviewers were calculated for presence of obstruction, active inflammation versus chronic stricture, and ancillary findings. Forty-two patients underwent surgery or colonoscopy within 3 months. Results. Kappa was 0.84 for presence of abnormality versus a normal exam and 0.89 for differentiating active inflammation from chronic stricture. Level of agreement for presence of skip areas, abscess formation, and fistula was 0.62, 0.75, and 0.78, respectively. In the subset with "gold standard" follow-up, there was 83% agreement. Conclusions. MBCT is a low-radiation technique with good to very good interobserver agreement for determining presence of obstruction and degree of disease activity in patients with Crohn's disease. Further investigation is required to refine parameters of disease activity compared to CT enterography and small bowel follow through.