The role of DTI in early detection of cervical spondylotic myelopathy: a preliminary study with 3-T MRI

INTRODUCTION

The radiological diagnosis of cervical spondylotic myelopathy (CSM) has to be made as soon as possible, since surgery performed in earlier stages during the course of CSM was reported to be more successful when compared with later stages. We hypothesized that diffusion tensor imaging (DTI) may detect CSM in earlier stages, before the appearance of signal increase in T2-weighted sequences.

METHODS

A total of 16 patients with neurological signs and symptoms of CSM but without hyperintensity in spinal cord on T2-weighted sequences enrolled in the study. The magnetic resonance (MR) examinations were performed on a 3-T MR imaging system. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps were generated on axial plane. The ADC and FA measurements in each individual were made at the level of most severe cervical canal stenosis and at a nonstenotic level. Student's t test was used to compare FA and ADC values of the spinal cord in stenotic and nonstenotic segments. We also investigated if there was a correlation between DTI parametrics and duration of clinical symptoms by using Pearson correlation analysis.

RESULTS

All patients showed changes in DTI parametrics at stenotic segments. While FA values of the spinal cord at the stenotic level showed a statistically significant reduction, there was a statistically significant increase in the measured ADC values (p < 0.001). There was no statistical correlation between the duration of symptoms and DTI parametrics.

CONCLUSION

Our preliminary findings indicate that DTI may show abnormalities in the spinal cord before the development of T2 hyperintensity on conventional sequences in patients with CSM.

Diffusion tensor imaging and fibre tracking in cervical spondylotic myelopathy

OBJECTIVES

To (1) obtain microstructural parameters (Fractional Anisotropy: FA, Mean Diffusivity: MD) of the cervical spinal cord in patients suffering from cervical spondylotic myelopathy (CSM) using tractography, (2) to compare DTI parameters with the clinical assessment of these patients (3) and with information issued from conventional sequences.

METHODS

DTI was performed on 20 symptomatic patients with cervical spondylotic myelopathy, matched with 15 volunteers. FA and MD were calculated from tractography images at the C2-C3 level and compressed level in patients and at the C2-C3 and C4-C7 in controls. Patients were clinically evaluated using a self-administered questionnaire.

RESULTS

The FA values of patients were significantly lower at the compressed level than the FA of volunteers at the C4-C7 level. A significant positive correlation between FA at the compressed level and clinical assessment was demonstrated. Increased signal intensity on T2-weighted images did not correlate either with FA or MD values, or with any of the clinical scores.

CONCLUSION

FA values were significantly correlated with some of the patients' clinical scores. High signal intensity of the spinal cord on T2 was not correlated either with the DTI parameters or with the clinical assessment, suggesting that FA is more sensitive than T2 imaging.

The correlation of diffusion-weighted magnetic resonance imaging in cervical compression myelopathy with neurologic and radiologic severity

STUDY DESIGN

A retrospective evaluation of diffusion-weighted imaging, apparent diffusion coefficient (ADC) maps, and T2-weighted images in patients with cervical compression myelopathy.

OBJECTIVE

To correlate high signal intensity on ADC maps and T2-weighted images to neurologic severity and radiologic spinal cord compression.

SUMMARY OF BACKGROUND DATA

Previous studies indicated that the ADC map was more sensitive in detection of cervical compressive myelopathy than T2-weighted imaging. The relationship to neurologic severity has not been previously published.

METHODS

In 100 patients with or without cervical compressive myelopathy, the magnetic resonance appearance of the spinal cord on ADC maps and T2-weighted images was evaluated independently by 2 readers. On the basis of the presence or absence of abnormality, patients were categorized into 4 groups by type of intramedullary change. The degree of canal compression and the Japanese Orthopedic Association (JOA) score for cervical myelopathy were compared among the 4 types.

RESULTS

The type I group consisted of 32 patients without signal change on either ADC maps or T2-weighted images. The type II group had 33 patients with high signal intensity only on the ADC map. The type III group contained 28 patients with high signal intensity on both the ADC map and the T2-weighted images. The type IV group comprised 7 patients with high signal intensity only on T2-weighted images. The degree of canal compression and the JOA scores were significantly different among the 4 groups (P < 0.005). Most type III (25 of 28) and type IV (7 of 7) patients had severe cord compression. Average JOA scores in each type were (I) 16.0, (II) 14.7, (III) 11.7, and (IV) 8.7.

CONCLUSION

ADC maps demonstrated internal changes in the early stages of chronic spinal cord compression, but had limitations for the detection of intramedullary changes in late-stage myelopathy.

Diffusion Tensor Imaging and 3D Tractography of the Cervical Spinal Cord Using the ECG-Gated Line-scan Technique. A Feasibility Study

Diffusion tensor (DT) magnetic resonance (MR) imaging in addition to conventional MR images provide valuable information on the brain. This study compared line scan DT imaging with and without the ECG-gating technique to estimate clinical usefulness of the line scan diffusion tensor image (LSDTI) with ECG-gating in evaluating spinal cord diseases in vivo. First, five healthy volunteers participated in the comparison study. LSDWI was performed in three to five sagittal sections with a pulsed-field-gradient diffusion preparation pulse employing two different b-values (0 and 700 s/mm(2)) along six directions. Apparent diffusion coefficient (ADC) maps and fractional anisotropy (FA) were calculated and three-dimensional tract reconstruction and color schemes of the spinal cord were obtained. Image quality and the acquisition time of each LSDTI were compared. Second, LSDTI with ECG-gating was performed in eighteen patients with cervical spinal cord disorders and evaluated by two neuroradiologists. Images with the ECG-gated technique were all superior to those without ECG-gating. Mean extended time for LSDTI with ECG-gating was approximately two minutes. In clinical use, the ADC and FA of spinal cord in patients with cervical spondylotic myelopathy statically changed. Moreover, demonstration of fibers was correlated with clinical symptoms. ECG-gating technique is preferable to LSDTI. The ADC and FA measurements and 3D fiber tracking of LSDTI with ECG-gating are promising methods to estimate cervical spinal cord pathology in clinical use.

Line scan diffusion tensor MRI at low magnetic field strength: feasibility study of cervical spondylotic myelopathy in an early clinical stage

PURPOSE

To implement line scan diffusion tensor MR imaging (LSDTI) on a 0.2 Tesla MR imager, and investigate the findings in the spinal cord of patients with cervical spondylotic myelopathy in an early clinical stage.

MATERIALS AND METHODS

Fourteen patients with clinical symptoms of cervical myelopathy underwent LSDTI. The signal-to-noise ratio (SNR) in the spinal cord and cerebrospinal fluid (CSF) was evaluated. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured. We classified the ROIs into two groups: 1) unaffected (no clinical symptoms and no abnormality on conventional images) and 2) affected (some clinical symptoms but no abnormal signal on conventional images). Three-dimensional (3D) fiber-tracking was also studied.

RESULTS

The isotropic ADC values (10(-3)mm2/sec) were 1.28 +/- 0.11 in group 1 and 1.59 +/- 0.23 in group 2. The FAs were 0.55 +/- 0.07 in group 1, and 0.47 +/- 0.11 in group 2. The ADC value in group 2 increased (P < .001, Mann-Whitney U-test) and the FA in group 2 decreased (P = 0.24) on average, compared to those in group 1. 3D fiber-tracking was successful in 64% (9/14) of the cases.

CONCLUSION

LSDT images at low field strength may be a sensitive method for elucidating the structural characteristics of spinal cord pathology in vivo. However, clinical correlation and a long-term follow-up study will be needed.

Early Experience Studying Cerebral Aneurysms with Rotational and Threedimensional Angiography and Review of CT and MR Angiography Literature

SUMMARY

From september 2000 to september 2001, 32 consecutive patients with ruptured intracranial aneurysms were examined with rotational and 3D reconstruction angiography using an Integris V5000 Philips Medical System: 39 aneurysms were detected. After a selective cerebral artery was catheterized with a 5F or 4F-catheter, 35 ml of contrast medium was intra-arterially administered at a rate of 4 ml/s and a 180 degrees rotational angiography was performed in eight seconds. This information was transferred to a computer (Silicon Graphics Octane) with software (Integris 3DRA, Philips Integris Systems) and a three-dimensional reconstruction was made. The information provided by Angio-3D was useful for evaluating the parent artery, aneurysmal sac, aneurysmal neck and arterial branches. It was also very useful in selecting the therapeutic method. For open surgery, this technique provides preoperative images that are useful for planning microsurgical approaches, especially in cases of large aneurysm showing complex surrounding arteries. For endovascular embolization, various anatomic characteristics of the aneurysm such as neck and sac size, shape, lobularity, parent artery and arterial branches adjacent to the aneurysmal neck must be demonstrated. This is very important to determine the best projection for embolization and to avoid multiple series. This is also essential in the choice of the first coil to create a good basket producing total occlusion. Microaneurysms are demonstrated well with this technique whereas this is difficult to do with conventional arteriography. The Angio-RM and Angio-CT literature show a lower sensitivity and specificity in comparasion with our experience with 3D IA-ROT-DSA. For this reason, we believe that 3D IA-ROTDSA is now the gold standard for patients presenting intracranial aneurysms.

Midterm outcome of partially thrombosed intracranial aneurysms treated with guglielmi detachable coils

SUMMARY

We evaluated the results of Guglielmi detachable coil (GDC) treatment in partially thrombosed aneurysms and determined if there is high rate of recanalisation on follow-up. Among 149 treated aneurysms in 141 patients, 25 CT- or MR-confirmed partially thrombosed aneurysms were selected for evaluation. The features of thrombosed aneurysms and percentage of occlusion were analysed on initial angiograms. Follow-up angiograms, which were available in 18 cases, were evaluated for aneurysm lumen recanalisation. The recanalisation rate was compared with that of non-thrombosed aneurysms treated with GDCs. Locations of aneurysms were as follows: cavernous carotid ten; ophthalmic four; p-com. two; MCA one; A-com. one; basilar tip four; midbasilar two; PICA one. The size of the aneurysm lumen ranged from 5 to 30 mm (mean 16.8 mm) on angiograms, but on cross sectional images the size of aneurysms ranged from 13 to 70 mm (mean 24.6 mm). The extent of aneurysmal thrombosis ranged from 10 to 90 per cent (mean 46.4 per cent). On initial GDC treatment, total to subtotal occlusion was achieved in 18 cases out of 25 (72%). Of the 18 follow-up angiograms, 14 cases (77.8%) showed recanalisation ranging from 10 to 60 per cent of aneurysm size. Luminal recanalisation was due to migration (10 of 14) or compaction (4 of 14) of coil masses. In two cases, symptoms recurred in association with aneurysm recanalisation, but in no instance was haemorrhage noted. Attempts for retreatment were made in ten cases with success in six. In comparison, 14 (15.9%) out of 88 nonthrombosed cases revealed recanalisation on follow-up angiography. Midterm follow-up angiograms in partially thrombosed aneurysms treated with GDC revealed a fivefold higher rate of recanalisation than in non-thrombosed cases. Close follow-up is necessary in patients with thrombosed aneurysms treated with GDCs.

Diffusion tensor MRI of the spinal cord

Apparent diffusion tensor (ADT) measurements on the spinal cord using a pulsed-field-gradient (PFG) multi-shot echo-planar imaging (EPI) sequence are presented. In a study of 10 healthy volunteers, the obtained rotationally invariant anisotropy information is compared to the results obtained by the rotationally dependent methods. The water diffusivity in the direction parallel to the fibers was found to be almost 2.5 times higher than the average diffusivity in directions perpendicular to the fibers and showed cylindrically symmetric anisotropy characteristics. The influence of partial volume effects and the point spread function on the measured results was evaluated, and it was the concluded that a resolution of 1 mm in the read and phase directions is required to obtain unbiased values. Possible clinical implications were demonstrated by investigating the diffusion characteristics of 10 patients suffering from narrowing of the cervical canal. The changes in the diffusion characteristics were found to be large enough to allow a robust detection of diffusion changes in the spine, even in cases in which conventional T(2) and T(1) weighted images were unable to detect any lesion.

Endovascular treatment for intracranial aneurysms

SUMMARY

Concerning to the embolization for the intracranial aneurysms, the underlying theme of the discussion is presented with our experiences.

Endovascular Management of Intradural Berry Aneurysms. Review of 203 Consecutive Patients Managed between 1993 and 1998 Morphological and Clinical Results at Mid-Term Follow-up

SUMMARY

Endovascular management of intracranial arterial aneurysms (AA) is well described and performed by many teams. The aim of this work is to review a series of consecutive cases treated in our institution and to compare to the data available in the literature. 225 AA were seen in Bicêtre between 1993 and 1998 in 203 patients. 201 of them (in 180 patients) were treated by our group. The endovascular treatment, its indications, results and complications have been reviewed and studied. The clinical follow-up of the patients has been evaluated. A female dominance was noted (64.5%) with a mean age of patients of 44.3 years. 65.6% of patients were treated in the acute phase after intracranial haemorrhage, 72% of them being Hunt and Hess grade 1 or 2. Most of these AA (73.6%) were located in the anterior circulation. In 86.1% of cases the AA was smaller than 10 mm. 85.6% of the AA needed only one session of endovascular therapy. No mortality occurred in the group of unruptured AA. Overall management mortality was 11% in ruptured AA (3.5% in HH1-2, 30.3% in HH3-5).Technical or transient complications occured in 11.6% of cases, but permanent morbidity was seen in 3.1% of cases. Control angiograms were performed 3 months and one year after therapy. In doubtful cases a control at 6 months was also performed. 100% occlusion rate was noted in 60.8% of cases; 22.8% of AA were occluded between 90-99%, and 13.3% between 80-90%. Only 3.1% of AA had an occlusion rate of less than 80%. One patient with a ruptured basilar tip AA which was partially coiled regrew and rebled three months after. The patient declined the recommended complementary surgery. Clinical follow up of patients with ruptured AA treated by embolisation shows satisfactory results with 8.5% of GOS 1-2, 3.4% of GOS 3-4, and 11% of GOS 5 (mortality). Overpacking of the AA may not be necessary to protect patients from (re)bleeds over time. The related technical risks and increased costs of dense overpacking do not seem justified. Secondary thrombosis of the ruptured AA after coiling is more often seen than coil compaction. Analysis of the AA architecture and recognition of false aneurysms are mandatory in order to obtain good clinico-morphological logical results.