Hubert Gufler

MR imaging of the carpal tunnel

OBJECTIVE Investigations were conducted regarding changes of carpal tunnel shape during wrist motion and the variations of space for the median nerve as well as the preoperative signs of carpal tunnel syndrome (CTS) and the postoperative restitution. METHODS Axial MR images (1.0 T) were performed at the level of the distal radioulnar joint, pisiforme bone and hook of hamate level of 20 wrists of patients with clinical symptoms of CTS and further 20 wrists of volunteers. This was conducted with the wrist in neutral position, 45 degrees extension and 45 degrees flexion. T2-weighted signal intensity of the median nerve were measured in 18 patients pre- and postoperatively. RESULTS The increase of the cross-sectional area of the median nerve at the pisiform level and the flattening of the median nerve at the hook of hamate level as well as the volar bowing of the flexor retinaculum at the pisiform and hook of hamate level were significantly greater in patients with CTS than in those with normal wrists (P < 0.05-0.001). In postoperative follow-up studies the distal flattening of the median nerve recovered in 94%. The signal intensity of the median nerve on T2-weighted images decreased in 67%. CONCLUSIONS Flexion at the pisiform and hamate level as well as extension at the pisiform level narrows the space available for the median nerve potential leading to compression of the median nerve. MR imaging is accurate and reliable for diagnosis and postoperative follow-up of CTS.

Pelvic floor descent: Dynamic MR imaging using a half-fourier RARE sequence

Dynamic magnetic resonance imaging (MRI) using a single shot fast spin‐echo technique was evaluated as a noninvasive alternative to cystourethography or colpocystorectography in patients with pelvic organ prolapse and/or urinary incontinence. Thirty‐two patients were included in this prospective study. Colpocystorectography was performed in 10 patients who previously had undergone hysterectomy and in 2 patients without history of hysterectomy with clinical suspicion of rectoceles. Bead‐chain cystourethrography was performed in 20 patients without hysterectomy. For dynamic MRI, a single‐slice half‐Fourier RARE sequence (imaging time 2 seconds) was used to depict the pelvic organs at different levels of pelvic strain. The results obtained with dynamic MRI were correlated with the x‐ray findings. All 17 cystoceles, 10 rectoceles, 2 enteroceles, and 7 vaginal prolapses could be demonstrated on MRI. Diagnostic information gained from these images was equivalent to that obtained with colpocystorectography and superior to that obtained with cystourethrography; with the latter, important findings were missed (four rectoceles). We conclude that dynamic MRI of the pelvic floor with a half‐Fourier RARE sequence can reliably detect descents of all three pelvic compartments, that it requires no contrast agent, and that no radiation exposure is involved.J. Magn. Reson. Imaging 1999;9:378–383.

Cine-mr imaging of the shoulder

Purpose: Shoulder lesions are usually examined with the joint in only one or two positions. We examined the shoulder with the joint in a variety of positions. We also assessed the application of cine-MR to the detection of instability and impingement Material and Methods: the cine-MR examinations were performed in 30 patients and 15 healthy volunteers. We used an open 0.2 T system and a closed 1.0 T system. Spoiled gradient echo 2D T1-weighted images and turbo spin-echo T1- and T2-weighted images were obtained with a field of view of 180 mm. the examinations were videotaped and evaluated later Results: Normal variations of the glenohumeral joint were easy to recognize. Subluxations and luxations of the humeral head as well as rupture of the labrum were identified. It was also possible to identify the labrum with a signal change after arthroscopic refixation. and we were able to objectively assess distances between the osseous structures during dynamic movement Conclusion: Unlike static MR, cine-MR would appear to be useful in visualizing the capsular ligament complex of the gleno-humeral joint in impingement and instability. It also provides information on dynamic changes and may thus prove to be an important tool for shoulder diagnostics. the method may provide an early diagnosis in the sub-acromial impingement syndrome

Comparison of cystourethrography and dynamic MRI in bladder neck descent.

PURPOSE The purpose of this work was to test whether there are statistically significant differences between dynamic MR and lateral cystourethrogram measurement results in patients with bladder neck descent. METHOD Twenty-seven women (39-83 years old, mean 60.6 years old) with urinary incontinence and bladder neck descent were examined by dynamic MRI using a single shot fast spin echo sequence with half-Fourier data acquisition. Bladder neck position, angle of inclination of the urethral axis, posterior vesicourethral angle, and depth of cystoceles were measured at perineal contraction and at maximal pelvic strain. The nonparametric Wilcoxon test for paired values was used to analyze whether there were statistically significant differences between lateral cystourethrogram and dynamic MR measurement results. The Spearman correlation coefficient (rs) was calculated for all parameter pairs. RESULTS Measurements at maximal pelvic strain showed the greatest levels of agreement between MRI and cystourethrography. The best results were attained for the cystocele measurements (p > 0.5, rs = 0.95). Bladder neck position showed the second best agreement; if MR measurements were corrected by 0.46 cm, no statistically significant difference (p > 0.2, rs = 0.92) was calculated. Measurements at perineal contraction tallied least, probably due to the different positions adopted during the two examinations. CONCLUSION Measurement data on dynamic MRI for the bladder neck position and the extension of cystocele at maximal pelvic strain are comparable with lateral cystourethrogram data.

MRI of lymphomas of the orbits and the paranasal sinuses

PURPOSE The purpose of this study was to point out MR characteristics of non-Hodgkin lymphomas of the orbits and the paranasal sinuses and the benefit of fat-suppressed contrast-enhanced sequences. METHOD The MR images of 16 patients with lymphoma of the orbits and the paranasal sinuses were retrospectively analyzed for signal intensity, contrast enhancement, bone destruction, and mass effect. The findings were confirmed by means of biopsy (Stage IE disease) or follow-up imaging after chemotherapy (Stage IV disease). RESULTS MRI clearly delineated the extension of the lymphomas. On the T1-weighted images, the signal intensity of the lymphoma was hypointense compared with the gray matter of the brain in 12 cases and intermediate in 4 cases. The T2-weighted fast SE images showed a hyperintense signal in 12 cases, intermediate in 3 cases, and even hypointensity in 1 case. All lesions enhanced after intravenous Gd-DTPA administration, reliably visible in the T1-weighted fat-suppressed sequences but not visible in three cases in the T1-weighted SE sequences. Bony wall destruction was evident in cases with paranasal but never in isolated orbital lymphoma. CONCLUSION While extension of lymphoma can be accurately described by MRI, a specific diagnosis is not achievable on the basis of signal intensities and enhancement patterns alone. Therefore, at least in cases of suspected Stages IE and IIE, biopsy proof is needed. Fat-suppressed contrast-enhanced sequences possess the highest detection rate and should therefore always be applied.

Differentiation of Adrenal Adenomas From Metastases With Unenhanced Computed Tomography

Objective: To investigate whether the diagnostic accuracy of unenhanced computed tomography (CT) regarding the differentiation of adrenal adenomas from adrenal metastases is increased by applying a combination of morphologic criteria instead of only measuring the density values of the tumor. Patients and Methods: Unenhanced CT scans of 56 patients with an adrenal mass and a history of an extra-adrenal malignancy were analyzed for size, attenuation, contour, and structure characteristics of the adrenal tumor. Coefficients yielded by multiple logistic regression analysis were used for the construction of an additive total score (score S) that included several diagnostic criteria. The reliability of the total score and all parameter combinations was tested by receiver operating characteristic (ROC) analysis. The nature of the adrenal lesion was determined by follow-up CT (40 patients), percutaneous biopsy (15 patients), or surgery (1 patient). Twenty-four of the neoplasms were adenomas, and 32 were found to be metastases. Results: The score of the combined CT parameters showed the largest area under the ROC curve. The highest predictive power indicated by the model was calculated at a cutoff value of 7.05, with a sensitivity of 100% and a specificity of 96.8% for the detection of metastases. At 6.85 points as the cutoff value, the scoring system still maintained a sensitivity of 95.8% and a specificity of 96.9%. Conclusion: The differentiation between adrenal adenomas and metastases is improved by applying our scoring system compared with any single parameter alone. The total score is obtained by adding 10% of the density values to the size in centimeters, plus 2 if the contour of the lesion is blurred and plus 1 if the structure is inhomogeneous. By setting the threshold at 7 points, all but 1 lesion were classified correctly.

Digital optical card : a promising technology for documentation and communication of images

Purpose: To assess a patient-oriented digital optical card (OC) for documentation and communication of images using the analysis of breast microcalcifications to illustrate its resolution power. Methods: Fifty film mammograms with histologically proved clustered microcalcifications were digitized using a 5 lp/mm CCD-scanner. A region of interest containing the cluster was selected for documentation on an OC as an overview OC-image and as a magnified OC-image (5 lp/mm). The shape (spherical/nonspherical) as well as the total number of microcalcifications were quantitatively analyzed by 2 radiologists. Results: The detection rate for total number of overall and spherical microcalcifications using digital media was significantly reduced (p<0.01) compared to analog mammography. There were no significant differences in the detection rate of nonspherical microcalcifications between film mammograms (100%) and magnified section OC-images (92.7%). The overview OC-image revealed 72% of those calcifications (p<0.01). Conclusion: According to our results, this technology is not appropriate for diagnosis of breast microcalcifications, but may be a promising communication digital medium for transmitting an image/report unit to referring physicians.