Clinical evaluation of a speed optimized T2 weighted fast spin echo sequence at 3.0 T using variable flip angle refocusing, half-Fourier acquisition and parallel imaging

This paper aims to demonstrate the capabilities of a speed optimized T(2) weighted single-shot turbo spin echo sequence, using parallel imaging, variable flip angle refocusing and half-Fourier acquisition (FAS-TSE), in comparison with a standard TSE (sTSE) sequence in patients with suspected multiple sclerosis (MS). 33 patients presenting with a clinically isolated syndrome (CIS) suggestive of MS were prospectively examined on a 3.0 T MR system using FAS-TSE and a sTSE sequence. The FAS-TSE (scan time 11 s) and the sTSE (scan time 122 s) were compared regarding lesion detectability, lesion contrast, grey/white matter contrast, overall image quality and artefacts. Scanning parameters affecting image contrast and spatial resolution were kept identical. 208 lesions were detected using the sTSE sequence compared with 183 lesions (88%) using the FAS-TSE. The FAS-TSE was rated inferior regarding lesion contrast. The mean value/range/standard deviation of the lesion/white matter contrast were 0.26/0.06-0.49/0.089, respectively, with the sTSE vs 0.21/0.04-0.40/0.081 with the FAS-TSE. The FAS-TSE was rated inferior regarding overall image quality, but superior regarding motion artefacts. The grey/white matter contrast was qualitatively judged as comparable for both sequences. FAS-TSE provides sufficient T2-SE contrast and diagnostic image quality for whole brain studies in 11 s. It is suited to reduce motion artefacts in restless patients and for fast acquisition of additional scanning planes.

Fusion of MRI and CT with Subdural Grid Electrodes

In patients with drug-resistant focal epilepsies subdural grid electrodes may be implanted to determine the seizure onset zone and eloquent cortex areas. Since the spatial relationship of the grid to the underlying brain is poorly visualized on MRI, we co-registered MRI before and CT after implantation of subdural grid electrodes. In this study we sought an appropriate algorithm to combine both imaging modalities. We compared six different co-registration algorithms including surface-oriented, mutual information-based and landmark-based methods. The resulting overlay matrices were analyzed by calculating rotational and translational shifts and by judging co-registered MRI and CT scans visually. A brain surface oriented method had the lowest rotational (axial 0.7 +/- 0.6 degrees; coronal 1.7 +/- 1.1 degrees; sagittal 1.9 +/- 1.8 degrees) and translational shifts (3.7 +/- 1.3 mm). It was judged visually to be the best, had a low intra- and inter-observer variability, and lasted approximately 15 minutes. This algorithm is recommended when co-registering MRI before and CT after implantation of subdural grid electrodes. Skin-, voxel-, and landmark-based algorithms are less accurate, which is most likely due to postsurgical deformation of extra- and intracranial soft tissue.

[Brace effect in scoliosis in the sagittal plane - an MRI study]

AIM

Using magnetic resonance (MR) imaging we studied the brace effect in scoliosis in the sagittal plane.

METHOD

In 38 patients with idiopathic scoliosis (mean age 13.4 years) MR total spine imaging was carried out to investigate the immediate effect of bracing in the sagittal plane. There were 19 thoracic, 13 S-shaped and 6 lumbar scoliosis. On conventional radiographs the mean Cobb angle of the thoracic curves was 31 degrees and of the lumbar curves 26 degrees. MR imaging was performed in the supine position with and without the brace in direct sequence. On the sagittal MR projection the Cobb angle was measured between T 4 and T 12 and between T 12 and L 5.

RESULTS

On the coronal MR images the mean correction with brace was 23 % of the thoracic curves and 29 % of the lumbar curves. The mean, sagittal Cobb angle (T 4 - T 12) was 14 degrees without brace and 12 degrees with brace. For the lumbar curves the mean sagittal Cobb angle (T 12 - L 5) was 32 degrees without brace and 31 degrees with brace. In the paired t-test these differences were significant.

CONCLUSION

Using MR total spine imaging the brace effect in scoliosis could be depicted in the sagittal plane. In the thoracic spine a correction of the lordotic deformity could not be observed.

A new method of MR total spine imaging for showing the brace effect in scoliosis

Bracing is a method of early, nonsurgical treatment for scoliosis, but a hypokyphotic effect on the thoracic spine is reported. We developed a magnetic resonance tomography (MR) procedure presenting an image of the whole spine in the coronal and sagittal planes (MR total spine imaging), and studied the brace effect, using this technique. We examined 26 female patients with idiopathic scoliosis treated with a Cheneau brace (mean age, 13.2 years; mean duration of brace treatment at the time of investigation, 1.5 years). The MR examinations were performed with the patient in the supine position with and without the brace in direct sequence. As measured on the coronal MR images, the thoracic curve was corrected, on average, from 29 degrees to 22 degrees (mean correction, 24%). There was a slight reduction in the sagittal Cobb angle measured between T4 and T12 (mean sagittal Cobb angle without brace, 14 degrees; with brace, 12 degrees ), which was still a significant change. MR total spine imaging could be a useful tool for studying the brace effect in scoliosis in two planes. Using this technique, we found reduced sagittal Cobb angles for the thoracic kyphosis with brace. Because there is no radiation exposure, the MR procedure has a potential use in the monitoring of brace treatment.

[Sagittal Cobb-angle measurements in scoliosis with MRI whole spine imaging]

AIM

A newly developed MR procedure allows imaging of the whole spine in coronal and sagittal planes. We studied the use of total spine MR imaging in measuring sagittal Cobb angles in scoliosis.

METHOD

64 patents with idiopathic scoliosis (mean age 18.1 years, 35 thoracic, 20 double major, and 9 lumbar curves) and 27 patients without scoliosis were consecutively examined. The MR images were acquired in the supine position. The sagittal Cobb angles were measured between T4-T12 and between T12-L5.

RESULTS

For the group of the thoracic and double major scoliosis the mean sagittal Cobb angle (T4-T12) was 13 degrees and for the group without scoliosis 23 degrees, which was a significant difference (p < 0.01, Mann Whitney-U-test). There was a negative correlation between the sagittal Cobb angles (T4-T12) and the lateral, thoracic curves. The mean sagittal Cobb angle (T12-L5) of the group with lumbar and double major curves was 35 degrees, which was not a significant difference when compared to 37 degrees of the non-scoliotic group.

CONCLUSION

Using total spine MR imaging the lordotic aspect of the thoracic deformation in scoliosis can be reliably measured. Because of the absent radiation exposure the sagittal MR reconstructions could be used as an additional imaging in monitoring scoliosis.

A new MRI technique for imaging scoliosis in the sagittal plane

The purpose of the present study was to introduce a new magnetic resonance imaging (MRI) procedure showing the whole spine in a coronal and sagittal plane, and to study the assessment of sagittal Cobb angle measurements using this technique. Prospectively we studied 32 patients (average age 14.8 years) with idiopathic scoliosis (mean thoracic Cobb angle 33 degrees on radiograph) and 18 patients (average age 14.5 years) without scoliosis. The MRI investigation was carried out in a standard supine position. The cervical and upper thoracic spine and the lower thoracic and lumbar spine were measured on a 1.5-T Gyroscan ACS-NT Powertrak 6000 system. An algorithm was developed to combine the results of the cranial and caudal scans into a coronal and a sagittal image of the whole spine (MR total spine imaging). Measurement of the sagittal Cobb angle conducted ten times by four independent investigators revealed an intraobserver variance of 1.6 degrees and an interobserver variance of 1.8 degrees. In the group with scoliosis the mean sagittal Cobb angle from T4 to T12 was 12 degrees (range -3 degrees to 24 degrees) and in the group without scoliosis 22 degrees (range 16 degrees to 30 degrees), which was a significant difference. MR total spine imaging makes it possible to image scoliosis in the sagittal plane. On these MR projections, idiopathic thoracic scoliosis was identified by a reduced sagittal Cobb angle. MR total spine imaging would allow monitoring of scoliosis in the sagittal plane, which can reveal relevant clinical data without radiation exposure.

Use of fluorine-18 fluoro-2-deoxy-D-glucose positron emission tomography in assessing the process of tuberculous spondylitis

Fluorine-18 fluoro-2-deoxy-D-glucose positron emission tomography can be used to quantify the pathologic increase in glucose metabolism of inflammatory processes. Preliminary studies indicate a high level of sensitivity and specificity in detecting and identifying chronic osteomyelitis. This case study shows that positron emission tomography can be used to assess the process of inflammatory activity in tuberculous spondylitis. This technology also has the advantage of higher spatial resolution compared with other nuclear medicine procedures. In addition, it can differentiate between bone and soft tissue infection and allows imaging in the presence of metal implants.

[Spiral CT of the head-neck area: the advantages of the early arterial phase in the detection of squamous-cell carcinomas]

PURPOSE

To determine if scanning in the arterial phase improves detection of squamous cell carcinomas in the pharynx and larynx.

METHODS

In a prospective clinical study 20 patients with a pharyngeal or laryngeal carcinoma were examined with by spiral CT. 80 ml lopromid were intravenously injected as a bolus with a rate of 3 ml/sec. Two consecutive spiral CT scans were performed with start-delay times of 20 and 70 seconds respectively. Delineation and contrast enhancement of tumours, cervical lymph nodes and vessels were evaluated. The radiodensities (HU) of tumors, lymph nodes vessels, pharyngeal wall and muscle were measured.

RESULTS

Comparing early and late start delay time scans tumor assessment in the early phase was better in 58%, less in 16% and equal in both scans in 26%. 82% of the pathologic lymph nodes had more peripheral enhancement than surrounding muscle tissue. During the arterial phase the measured radiodensities of the common carotid artery and jugular vein were significantly higher than in the second phase.

CONCLUSION

Contrast-enhanced special CT permits accurate morphologic assessment (size, infiltration) of pharyngeal and supraglottic laryngeal squamous cell carcinoma, while pathologic lymph nodes already have a sufficient contrast enhancement for the detection.

[MR whole-spine recording: computer-assisted simulation of the conventional x-ray technic]

PURPOSE

Development of an MR-based imaging technique for the spine allowing reduction of frequency of conventional Nadiographs in the monitoring of juvenile scoliosis.

PATIENTS AND METHODS

25 patients between the ages of 6 to 36 years were examined in supine position. Two examinations of the cervical and upper thoracic spine and of the lower thoracic and lumbar spine were performed with a 1.5 T Gyroscan ACS-NT Powertrak 6000 system with body coil employing 3D EPI-sequence (TR 17 ms, TE 9 ms, flip angle 20 degrees, field of view 450 mm) or 3D FFE sequences (TR 9 ms, TE 4.5 ms, flip angle 20 degrees, field of view 450 mm) and pulse-oximetry gating. 64 coronal slices were acquired with reconstructed slice thickness of 2 mm. Image processing was performed with an algorithm merging acquisition results into two single images in the coronal and sagittal orientations allowing measurement of the Cobb angle.

RESULTS

Mean examination time was 14 minutes per patient. Mean data processing time was seven minutes. Interobserver variance of determination of the Cobb angle was 1.8 degrees.

CONCLUSIONS

It is to be hoped that MR whole spine projection will allow a reduction of the frequency of conventional projection in the monitoring of juvenile scoliosis.