Diffusion-Weighted Zonal Oblique Multislice-EPI Enhances the Detection of Small Lesions with Diffusion Restriction in the Brain Stem and Hippocampus: A Clinical Report of Selected Cases.

Diffusion restriction is the morphologic hallmark of acute ischemic infarcts and excitotoxic brain injury in various cerebral pathologies. Diffusion restriction is visible as hyperintensity on DWI and as hypointensity on ADC maps. Due to the vicinity of multiple anatomic structures in the brain stem and hippocampus, very small lesions with diffusion restriction may result in severe clinical symptomatology, but these small lesions easily go undetected on standard cerebral DWI due to insufficient spatial resolution, T2* blurring, and image artifacts caused by susceptibility-related image distortions. Diffusion-weighted zonal oblique multislice-EPI with reduced FOV acquisition permits a considerable increase in spatial resolution and enhances the visualization of very small pathologic lesions in the brain stem and hippocampus. Improved performance in the depiction of different pathologic lesions with diffusion restriction in the brain stem and hippocampus using this sequence compared with standard DWI in selected cases is presented.

Displacement of malignant cells into the portal triad of the liver results in reduced liver perfusion, mimicking segmental Fatty liver.

Liver steatosis is often observed in different clinical situations. Oncological patients undergoing systemic therapy often develop liver steatosis, which can be diagnosed with normal routine scans such as CT and ultrasound. In this case report, we show that an isolated infiltration of the portal triad with tumor cells could mimic a fatty-like infiltration of the liver. Radiologists and clinicians should be aware of this pitfall and should perform a biopsy in cases of doubt.

Comparison of standardized pre- and postoperative functional pelvic cine-MRI in patients with a bulbourethral composite suspension due to post-prostatectomy incontinence.

OBJECTIVES: To compare functional pelvic cine-MRI in patients with post-prostatectomy incontinence before and after implantation of a bulbourethral composite suspension. PATIENTS AND METHODS: Functional pelvic 1.5 T cine-MRI was performed at rest, under standardized Valsalva pressure and during micturition in six patients with post-prostatectomy incontinence before and 3 months after a bulbourethral composite suspension. Visibility and positioning of the implant as well as membranous urethral length (MUL) and positioning of the bladder neck (BN) in comparison with the pubococcygeal line (PCL) were evaluated. Clinical outcome was measured by patient-reported pad use and standardized questionnaires (ICIQ-UI SF and I-QOL). Paired data were tested with a Wilcoxon signed-ranks test. RESULTS: Surgery was successfully performed in all patients. All patients returned to complete voiding. The ICIQ-UI SF score decreased significantly from median 16.5 to 5 (p = 0.016). I-QOL increased significantly from 70.5 to 93.5 (p = 0.047). Pad use improved from median 2 pads to 0 pads postoperatively (p = 0.031). Four of six patients were completely pad-free, and 2 were failures with persisting urinary incontinence. MRI revealed significant differences of the MUL at rest with median of 8 mm pre- and 13 mm postoperatively (p = 0.016). BN showed a significant elevation with respect to PCL under Valsalva with in median 0.5 to 5 mm postoperatively (p = 0.016). No significant MRI differences were found between patients showing clinical success or failure. CONCLUSIONS: The bulbourethral composite suspension was associated with an increase in urethral length, urethral coaptation zone and bladder neck elevation, implying a non-compressive mode of action.

Combining fMRI and DTI: a framework for exploring the limits of fMRI-guided DTI fiber tracking and for verifying DTI-based fiber tractography results.

A powerful, non-invasive technique for estimating and visualizing white matter tracts in the human brain in vivo is white matter fiber tractography that uses magnetic resonance diffusion tensor imaging. The success of this method depends strongly on the capability of the applied tracking algorithm and the quality of the underlying data set. However, DTI-based fiber tractography still lacks standardized validation. In the present work, a combined fMRI/DTI study was performed, both to develop a setup for verifying fiber tracking results using fMRI-derived functional connections and to explore the limitations of fMRI based DTI fiber tracking. Therefore, a minor fiber bundle that features several fiber crossings and intersections was examined: The striatum and its connections to the primary motor cortex were examined by using two approaches to derive the somatotopic organization of the striatum. First, an fMRI-based somatotopic map of the striatum was reconstructed, based on fMRI activations that were provoked by unilateral motor tasks. Second, fMRI-guided DTI fiber tracking was performed to generate DTI-based somatotopic maps, using a standard line propagation and an advanced fast marching algorithm. The results show that the fiber connections reconstructed by the advanced fast marching algorithm are in good agreement with known anatomy, and that the DTI-revealed somatotopy is similar to the fMRI somatotopy. Furthermore, the study illustrates that the combination of fMRI with DTI can supply additional information in order to choose reasonable seed regions for generating functionally relevant networks and to validate reconstructed fibers.