Magnetic resonance imaging of cranial nerves at 7 Tesla.

PURPOSE: The aim of this study was to demonstrate the feasibility of cranial nerve (CN II-XII) imaging with 7 Tesla magnetic resonance imaging (MRI). METHODS: In this study four sequences were evaluated in three healthy volunteers using magnetization preparation rapid gradient echo (MPRAGE), constructive interference in steady state (CISS), true fast imaging with steady state precession (TrueFISP) and proton density (PD) T2-weighted turbo spin echo (TSE) sequences. RESULTS: It was found that MPRAGE did not always provide sufficient contrast to delineate in particular small CNs but displayed an overall good identification rate. The T2 sequence was not able to adequately differentiate the small CNs but showed a very good contrast between nerves and cerebrospinal fluid (CSF). As at lower magnetic fields steady state sequences displayed a high identification rate of all CNs in the axial plane but CISS suffered from susceptibility and pulsation artifacts, furthermore it was limited as no parallel imaging could be performed. The TrueFISP technique was reliable in identifying most CNs although suffering from banding artifacts. CONCLUSIONS: The TrueFISP sequence showed superior spatial resolution and contrast in comparison to the other sequences for imaging of CNs at 7 T.

[Whole-body diffusion-weighted imaging in oncology: technical aspects and practical relevance]. / Ganzkörperdiffusionsbildgebung in der Onkologie: Technische Aspekte und praktischer Stellenwert.

This review illustrates the relevance of whole-body diffusion-weighted imaging (WB-DWI) in the field of oncological imaging. WB-DWI is an alternative method to positron-emission tomography/computed tomography (PET/CT) due to the lack of radiation and lower examination costs. Technical aspects of WB-DWI and the current role of the method in cancer imaging regarding practical requirements in oncology are presented.

Suitability of semi-automated tumor response assessment of liver metastases using a dedicated software package.

PURPOSE: To evaluate the suitability of semi-automated compared to manual tumor response assessment (TRA) of liver metastases. MATERIALS AND METHODS: In total, 32 patients with colorectal cancer and liver metastases were followed by an average of 2.8 contrast-enhanced CT scans. Two observers (O 1, O 2) measured the longest diameter (LD) of 269 liver metastases manually and semi-automatically using software installed as thin-client on a PACS workstation (LMS-Liver, MEDIAN Technologies). LD and TRA ("progressive", "stable", "partial remission") were performed according to RECIST (Response Evaluation Criteria in Solid Tumors) and analyzed for between-method, interobserver and intraobserver variability. The time needed for evaluation was compared for both methods. RESULTS: All measurements correlated excellently (r>or=0.96). Intraobserver (semi-automated), interobserver (manual) and between-method differences (by O 1) in LD of 1.4+/-2.6 mm, 1.9+/-1.9 mm and 2.1+/-2.0 mm, respectively, were not significant. Interobserver (semi-automated) and between-method (by O 2) differences in LD of 3.0+/-3.0 mm and 2.6+/-2.0 mm, respectively, reflected a significant variability (p<0.01). The interobserver agreement in manual and semi-automated TRA was 91.4 %. The intraobserver agreement in semi-automated TRA was 84.5%. Between both methods a TRA agreement of 86.2% was obtained. Semi-automated evaluation (2.7 min) took slightly more time than manual evaluation (2.3 min). CONCLUSION: Semi-automated and manual evaluation of liver metastases yield comparable results in response assessments and require comparable effort.

[Liver biopsy under guidance of multislice computed tomography: comparison of 16G and 18G biopsy needles]. / Leberbiopsie mit Hilfe der Mehrschichtcomputertomographie : Vergleich zwischen 16-G- und 18-G-Biopsienadeln.

BACKGROUND: Percutaneous cutting needle biopsy of focal liver lesions under CT guidance has established itself as a standard method. The purpose of this study was to evaluate which diagnostic quality can be achieved under guidance of multislice CT (MSCT) and with the use of different needle sizes. METHODS: The data of 163 MSCT-guided core biopsies of focal liver lesions were evaluated. A 16G biopsy needle was used in 121 cases and an 18G needle in 42 cases. RESULTS: The sensitivity, specificity, and accuracy for all biopsies were 93.3, 100.0, and 94.5%. The corresponding values were 97.2, 100.0, and 97.5% for the 16G needle and 78.6, 100.0, and 85.7% for the 18G needle, respectively. A definite histological diagnosis could be obtained in 90.0% of the cases (16G 94.0%, 18G 75.8%). These differences were statistically highly significant. Bleeding complications were recognized in seven biopsies (4.3%). In one patient a fatal bleeding occurred after the biopsy. Median biopsy duration was 27 min. CONCLUSIONS: Core biopsy under MSCT guidance is a fast and very accurate method to obtain a histological diagnosis in focal liver lesions. The usage of a 16G needle in comparison to an 18G needle yielded a significantly higher rate of correct results with regard to differentiation between benign and malignant disease as well as establishing a definite histological diagnosis. For an accurate diagnosis of liver lesions a 16G needle is recommended. After biopsy, the patients have to be closely monitored.