Gisbert Brinkmann

Dynamic changes of the spinal canal in patients with cervical spondylosis at flexion and extension using magnetic resonance imaging.

RATIONALE AND OBJECTIVES The authors determine the dynamic changes of the spinal canal during flexion and extension in patients with cervical spondylosis. METHODS Forty-six patients were studied inside a whole-body magnetic resonance (MR) scanner with between 50 degrees of flexion and 30 degrees of extension, using a positioning device. At neutral position (0 degree) and maximum flexion and extension sagittal T2-weighted turbo spin echo sequences were acquired. RESULTS A significant (P < or = 0.05) increase of spinal stenosis was found at extension (48%, 22 of 46 patients) when compared with flexion (24%, 11 of 46). Cervical cord compression was diagnosed at flexion in 5 patients (11%) and at extension in 9 patients (20%). Concerning the number of patients with cervical cord compression at flexion and extension, significant differences (P < or = 0.05) were found in patients with degenerative changes at four segments compared with patients with one segment involvement. CONCLUSIONS Magnetic resonance imaging identified a significant percentage of increased spinal stenosis at flexion and, especially, at extension, which was not observed at neutral position (0 degree). Flexion and extension MR imaging demonstrates additional information using a noninvasive technique concerning the dynamic factors in the pathogenesis of cervical spondylotic myelopathy.

Biomechanical aspects of the subarachnoid space and cervical cord in healthy individuals examined with kinematic magnetic resonance imaging

Study Design. In vivo flexion‐extension magnetic resonance imaging studies of the cervical spine were performed inside a positioning device. Objective. To determine the functional changes of the cervical cord and the subarachnoid space that occur during flexion and extension of the cervical spine in healthy individuals. Summary of Background Data. As an addition to static magnetic resonance imaging examinations, kinematic magnetic resonance imaging studies of the cervical spine were performed to obtain detailed information about functional aspects of the cervical cord and the subarachnoid space. The results were compared with published data of functional flexion‐extension myelograms of the cervical spine. Methods. The cervical spines of 40 healthy individuals were examined in a whole‐body magnetic resonance scanner from 50° of flexion to 30° of extension, using a positioning device. At nine different angle positions, sagittal T1‐weighted spin‐echo sequences were obtained. The images were analyzed with respect to the segmental motion, the diameter of the subarachnoid space, and the diameter of the cervical cord. Results. The segmental motion between flexion and extension was 11° at C2‐C3, 12° at C3‐C4, 15° at C4‐C5, 19° at C5‐C6, and 20° at C6‐C7. At flexion, a narrowing of the ventral subarachnoid space of up to 43% and a widening of the dorsal subarachnoid space of up to 89% (compared with the neutral position, 0°) were observed. At extension, an increase in the diameter of the ventral subarachnoid space of up to 9% was observed, whereas the dorsal subarachnoid space was reduced to 17%. At flexion, there was a reduction in the sagittal diameter of the cervical cord of up to 14%, and, at extension, there was an increase of up to 15%, compared with the neutral position (0°; these values varied depending on the cervical segment. Statistically significant differences (P < 0.05) were found between flexion and extension in the diameter of the ventral and dorsal subarachnoid space and in the diameter of the cervical cord. Conclusions. Compared with the results of previous studies using functional cervical myelograms, kinematic magnetic resonance imaging provides additional noninvasive data concerning the physiologic changes of the cervical subarachnoid space and the cervical cord during flexion and extension in healthy individuals.

Effect of a Patellar Realignment Brace on Patients with Patellar Subluxation and Dislocation Evaluation with Kinematic Magnetic Resonance Imaging

The object of this study was to evaluate the effect of a patellar realignment brace on patients with patellar subluxation or dislocation. Twenty-one patients (24 patellofemoral joints) with clinical evidence of patellar subluxation (N 16) or dislocation (N 5) were examined with the joint inside a positioning device to allow active-motion, kinematic magnetic resonance imaging. To analyze the patellar tracking pattern, the same imaging parameters (patellar tilt angle, bisect offset, and lateral patellar displacement) and section locations were used before and after application of a patellar realignment brace. No statistically significant differences were found in any of the three parameters for the patellofemoral relationships before or after wearing the patellar brace. The results indicated no stabilizing effect of the tested brace in patients with patellar subluxation or dislocation during active joint motion.

Kinematic MR imaging in surgical management of cervical disc disease, spondylosis and spondylotic myelopathy

Purpose: To estimate the clinical value and influence of kinematic MR imaging in patients with degenerative diseases of the cervical spine. Material and Methods: Eighty-one patients were examined with a 1.5 T whole body magnet using a positioning device. Cervical disc disease was classified according to clinical and radiographic findings into 4 stages: stage I=cervical disc disease (n=13); stage II=spondylosis (n=42); stage III=spondylosis with restricted motion (n=11); and stage IV=cervical spondylotic myelopathya (n=15). Findings on kinematic MR images were compared to those on flexion and extension radiographs, myelography, CT-myelography and static MR imaging. Furthermore, the influence of kinematic MR imaging on surgical management and intra-operative patient positioning was determined. Results: Additional information obtained by kinematic MR imaging changed the therapeutic management in 7 of 11 (64%) patients with stage III disease, and in 13 of 15 (87%) patients with stage IV disease. Instead of an anterior approach, a posterior surgical approach was chosen in 3 of 11 patients (27%) with stage III disease and in 6 of 15 patients (40%) with stage IV disease. Hyperextension of the neck was avoided intra-operatively in 4 patients (27%) with cervical spondylotic myelopathy, and in 1 patient with stage II (2%) and in 1 patient with stage III (9%) disease. Kinematic MR imaging provided additional information in all patients with stages III and IV disease except in 1 patient with stage III disease, when compared to flexion and extension radiographs, myelography, CT-myelography and static MR examination. Conclusion: Kinematic MR imaging adds additional information when compared to conventional imaging methods in patients with advanced stages of degenerative disease of the cervical spine.

A study of T1-weighted 31phosphorus MR-spectroscopy from patients with focal and diffuse liver disease.

31P-MR-Spectroscopy was performed in 28 patients with focal (n = 23) and diffuse (n = 5) liver disease and in 18 healthy volunteers. The spectra were obtained with a whole body scanner operating at 1.5 T by using a surface coil. To get T1-weighted 31P-spectra a short TR of 600 msec was taken, because T1-weighted spectra of focal liver disease were more significantly different from spectra from healthy volunteers than density weighted ones. The VOI from patients with focal superficial alterations showed a mean volume of 172 ml, with diffuse liver disease 196 ml, and from volunteers 158 ml. Focal tumors filled up the VOI on an average of 70%. This investigation demonstrated that PME/beta-ATP- and PDE/beta-ATP-ratios were sensitive indicators for focal liver disease. As a result of this study we could establish a significant increase of PME/beta-ATP- (0.75 +/- 0.30) and PDE/beta-ATP-ratios (1.68 +/- 0.62) in patients with superficial focal liver metastases (n = 19) compared to the control group (PME/beta-ATP: 0.49 +/- 0.17, PDE/beta-ATP: 1.24 +/- 0.24; t-test: p < 0.02). Patients with a hemangioma (n = 1), liver infarction (n = 1), empyema of gallbladder (n = 1) and a hepatic involvement by a malignant lymphoma (n = 1) showed a similar increase of PME/beta-ATP and/or PDE/beta-ATP. Up to now spectral changes seemed to be non-specific. The ratios of 31P metabolites of the cirrhoses (n = 4) and the fatty liver (n = 1) did not show any characteristic changes versus the volunteers.

Kinematic MR imaging of the ankle — initial results with ultra-fast sequence imaging

Purpose: In order to evaluate the advantages of ultra-fast MR sequences, kinematic MR imaging studies were performed in 4 patients with osteochondritis dissecans of the talus and in 12 healthy volunteers. Material and Methods: The patients and volunteers were placed inside a custom-made positioning device. Sagittal ultra-fast T2-weighted turbo gradient-echo sequences and HASTE sequences were obtained during active joint motion from dorsiflexion to plantar flexion. Eight sagittal slices were scanned separately to cover this ankle motion. In each slice, 8 to 10 images were obtained in 12-s or 18-s periods. Results: Adequate image quality for analyzing the normal kinematics of the ankle was obtained in all subjects. At surgery, the osteochondral fragment was found to be mobile in 3 of the 4 of the patients. In none of these cases was fragment mobility observed on kinematic MR imaging. No motion of the fragments was observed in the fourth patient, neither at surgery nor on kinematic MR imaging. Conclusion: Ultra-fast MR imaging sequences made it possible to produce kinematic MR imaging studies of active joint motion. The positioning device was useful for guiding joint motion in patients and for obtaining adequate image quality.

In vivo P-31-MR-spectroscopy of focal hepatic lesions. Effectiveness of tumor detection in clinical practice and experimental studies of surface coil characteristics and localization technique.

RATIONALE AND OBJECTIVESThe influence of partial tumor sampling in a volume of interest (VOI) on the ratios of phosphorus metabolites was examined by localized phosphorus magnetic resonance spectroscopy (P-31-MRS). Experiments were performed to investigate the characteristics of the surface coil used and precession of spatial localization. METHODSA total of 24 patients with liver metastases and 20 volunteers were studied by P-31-MRS. Patients were divided in two groups: VOI < 50% (n = 8) and VOI > 50% (n = 16) occupied by tumor. For evaluation of the surface coil and localization method (image selected in vivo spectroscopy), phantom studies were performed. RESULTSSuperficial focal liver tumors were detectable with a surface coil at a distance within the coil radius. The image selected in vivo spectroscopy permitted the study of phosphorus metabolism in a defined VOI. phosphomonoester/β-adenosine triphosphate and phosphodiester/β-adenosine triphosphate were elevated significantly in spectra of both patient groups.CONCLUSIONS. Detection of small tumor volumes within a VOI filled by less than 50% of the tumor is possible, with results statistically different from that in normal volunteers.

Influence of different fasting periods on P-31-MR-spectroscopy of the liver in normals and patients with liver metastases

The purpose of this study was to determine the influence of different fasting periods on the in vivo P-31-MR spectroscopy of the healthy liver and patients with liver metastases. Image-guided localized P-31-MRS was performed in 24 patients with liver metastases and in 20 healthy volunteers. The spectra were obtained with a whole body scanner operating at 1.5 T using a surface coil. The P-31-MRS was performed after a fasting period of 3–5 h (group 1) and after overnight fasting (group 2). The PME/β-NTP, PDE/β-NTP and Pi/β-NTP were calculated from P-31-MR spectra and were compared in relation to the nutrition status of the volunteers and patients. The PME/β-NTP and PDE/β-NTP were significantly increased in spectra of patients with metastases. There were no significant changes in the ratios of phosphorus metabolites in healthy liver tissue or in liver metastases after a fasting period of 3–5 h as compared with overnight fasting.

Skeletal involvement and follow-up in linear nevus sebaceous syndrome

Abstract. Linear nevus sebaceous syndrome is a rare neurocutaneous syndrome in which associated radiographic findings of the peripheral skeletal system are uncommon. We report a follow-up study of a patient with mainly unilateral changes of the skeletal system involving the thorax and the right arm and leg.

MR Angiography of the iliofemoral artery system

SummaryDuring the last years, magnetic resonance angiography (MRA) has become a widely used modality for intracerebral and carotid artery imaging. Due to technical limitations, the clinical impact of MRA in the iliofemoral arteries has been rather poor. New developments in MRA like ECG-triggered sequences and the occurrence of contrast-enhanced MRA has overcome most of these limitations. Therefore, a major advance in clinical use of these diagnostic tools can be predicted. This paper discussed the advantages of ECG-gated 2D-Phase contrast, ECG-gated 2D-Time-of-Flight and contrast enhanced FLASH 3D angiography sequences from a clinical point of view. 2D-PC-MRA is a robust technique, which provides an overview of the iliofemoral artery system in less than 5 minutes. Limitations are the true 2D impression of the sequence and the partial venous overlay. 2D-TOF-MRA on the other hand is time consuming, however it enables 3D reconstruction and effective venous suppression can be applied. Contrast enhanced MRA as the third sequence discussed provides high resolution images in less than 30 sec. However contrast bolus timing might be a problem. In conclusion the authors suggest a combination of 2D-PC-MRA and additional 2D-TOF sequences at questionable vacular areas as the modality of choice, due to the fact, that MRA of the iliofemoral arteries ist mostly only one step of a complete lower limb examination. Contrast MRA might become the method of choice in the future however problems with multiple contrast injections and upper limits of contrast dose have to be solved.ZusammenfassungWährend der letzten Jahre ist die Magnetresonanzangiographie (MRA) zu einer wertvollen klinischen Methode in der Diagnostik von krankhaften Prozessen der supraaortalen und der intrazerebralen Arterien geworden. Aufgrund technischer Limitationen wird sie jedoch im Körperstamm und insbesondere im Beckenbereich eher selten eingesetzt. Neue Entwicklungen wie die Einführung getriggerter Sequenzen oder der kontrastmittelunterstützten Verfahren machen jedoch eine Neubewertung des Verfahrens notwendig. Eine zunehmende Verbreitung des Verfahrens erscheint im Bereich der Beckenetage gerechtfertigt. Die vorliegende Arbeit stellt verschiedene Ansätze in der MRA vor, insbesondere werden Studien mit den Methoden der 2D-Phasenkontrast-MRA, der 2D-Time-of-flight-MRA und der kontrastmittelunterstützten MRA beschrieben. Die 2D-PC-MRA ist ein robustes Verfahren, welches einen Überblick über die Beckengefäße mit einer Untersuchungszeit von weniger als 10 min liefert. Limitationen sind hier die Zweidimensionalität des Verfahrens. Die 2D-TOF-MRA hat den Nachteil eines höheren Zeitaufwandes von 15–20 min, bietet jedoch den Vorteil der dreidimensionalen Rekonstruktion und der besseren venösen Absättigung. Die kontrastmittelverstärkte MRA ermöglicht hochaufgelöste Bilder mit Aufnahmezeiten von 25–90 s, abhängig von der gewählten Sequenz. Aufgrund der Erfahrungen in unserer Klinik empfehlen wir eine Kombination aus 2D-PC-MRA und 2D-TOF-MRA für die Diagnostik der Beckengefäße. In naher Zukunft könnte jedoch die kontrastmittelunterstützte MRA die Methode der Wahl sein.