Coronal STIR sequence, a simple adjustment to routine MRI protocol for extra-spinal sciatica and sciatica-like symptoms

The value of chemical shift imaging and T1-Dixon MRI in evaluation of structural changes in sacroiliac joint in ankylosing spondylitis

Background

The aim of this study was to assess the diagnostic value of dual gradient-echo T1-weighted sequence (in phase and out of phase) and the related Dixon images in evaluation of structural changes observed in sacroiliac joint in patients diagnosed with ankylosing spondylitis. Forty patients with low back pain were included in the study; they underwent T1-Dixon and routine MRI study on the sacroiliac joint in addition to pelvic CT.

Results

This study was carried out on forty patients, 27 (67.5%) males and 13 (32.5%) females, their mean age was 34.93 ± 11.21 years, and mean duration of symptoms was 8.1 ± 7.4 years. The mean Ankylosing Spondylitis Disease Activity Score ASDAS value was 4.03 ± 0.85 years. The most common structural change was subchondral fat deposition. Dixon MRI was significantly superior to T1WI in simple quantification of the amount of fat with P = 0.036 and excellent inter-rater reliability (96%), P = 0.0001. The number of erosions/backfills detected on Dixon was higher than that detected in T1WI with higher accuracy (97.5%) and excellent inter-rater reliability (95%), P = 0.0001. ASDAS showed significant positive correlation with erosion/backfill (r = 69, P = 0.0001) and with maximal fat deposition detected on Dixon (r = 32, P = 0.044). There were significant difference between the patients having high ASDAS and others having very high ASDAS scores regarding the sub-articular sclerosis (P = 0.013).

Conclusion

3D T1-based Dixon is a helpful imaging technique in proper assessment of different structural changes in sacroiliitis, its integration into routine MR protocol is recommend as it could yield a better depiction of erosive/backfill and fat deposition.

Global incidence of spinal perineural Tarlov's cysts and their morphological characteristics: a meta-analysis of 13,266 subjects

BACKGROUND

Spinal perineural Tarlov's cysts (TCs) are considered incidental findings that occasionally might exert pressure upon nerve roots and correspond with patients' signs and symptoms. Purpose of this meta-analysis is to deliver global incidence and characteristics (location, size, and shape) of TCs.

METHODS

Following PRISMA checklist, all major databases were searched by two authors for radiologic studies reporting incidence and morphologic features (location, size, and shape) of TCs. Anatomical Quality Assessment tool was applied for risk of bias evaluation. Meta-analysis of random-effects model was employed. Subgroup analysis for regional distribution, gender, sacral levels, age, correspondence with symptoms, and persistent genital arousal disorder (PGAD) were planned ahead.

RESULTS

22 radiologic studies of level 3 evidence involving 13,266 subjects were included. Global pooled prevalence of TCs was 4.18% (95% CI 2.47-6.30). Mean pooled sagittal diameter was 11.86 mm (95% CI 10.78-12.93). Sacral cysts strongly prevailed over the other segments. Of the sacral, S2 level was the most common (46.7% [95% CI 29.4-60.5]). Geographically, the highest incidence was found in Europe (6.07% [95% CI 1.49-13.00]), followed by North America (3.82% [95% CI 0.49-9.44]), and Asia (3.33% [95% CI 1.52-5.75]). TCs were more common in women than in men (5.84% vs 3.03%, p < 0.001, test of homogeneity, χ²). Subjects with PGAD had incidence of 37.87% (95% CI 2.45-81.75). TCs in pediatric population are rare-0.53% (95% CI 0.02-1.51). 15.59% of TCs corresponded with symptoms.

CONCLUSIONS

Spinal perineural (Tarlov) cysts are found in a minority of population. S2 level of the sacral bone is affected most frequently. There is female predominance. Correspondence with symptoms is seen in less than one-fifth of TCs. Studies with stronger evidence level are needed to corroborate the results. The purported high incidence in PGAD requires confirmation in case-control studies for the risk-ratio calculation.