Asif Saifuddin

Vertebral end-plate (Modic) changes on lumbar spine MRI: correlation with pain reproduction at lumbar discography

Abstract The vertebral end-plate has been identified as a possible source of discogenic low back pain. MRI demonstrates end-plate (Modic) changes in 20–50% of patients with low back pain. The aim of this study was to investigate the association between Modic changes on MRI and discogenic back pain on lumbar discography. The MRI studies and discograms of 58 patients with a clinical diagnosis of discogenic back pain were reviewed and the presence of a Modic change was correlated with pain reproduction at 152 disc levels. Twenty-three discs with adjacent Modic changes were injected, 21 of which were associated with pain reproduction. However, pain was also reproduced at 69 levels where no Modic change was seen. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for a Modic change as a marker of a painful disc were 23.3%, 96.8%, 91.3% and 46.5% respectively. Modic changes, therefore, appear to be a relatively specific but insensitive sign of a painful lumbar disc in patients with discogenic low back pain.

The variation of position of the conus medullaris in an adult population: A magnetic resonance imaging study

Study Design. Sequential study of magnetic resonance images of the lumbar spine. Objectives. To determine the variation in position of the conus medullaris in a living adult population without spinal deformity. Summary of Background Data. Cadaveric studies have shown that the position of the conus medullaris in the adult most commonly is located at L1‐L2. There have been several studies documenting the changing level of the conus throughout infancy and childhood, but there is no detailed study that documents the range of conus positions in a living adult population without spinal deformity. Methods. The T1‐weighted, midline, sagittal, spin‐echo magnetic resonance imaging studies of 504 patients were assessed to identify the tip of the conus medullaris. This location was recorded in relation to the upper, middle, or lower third of the adjacent vertebral body or the adjacent intervertebral disc. Results. The study group consisted of 231 men and 273 women with a mean age 46 years (range, 16‐85 years). Most patients were being examined for low back pain. Patients with spinal deformity were excluded. The mean conus position was the lower third of L1 (range, middle third of T12 to upper third of L3). The variation in conus positions followed a normal distribution. No significant difference in conus position was seen between male and female patients or with increasing age. Conclusions. The distribution of conus location in a large adult population was shown to range from the middle third of T12 to the upper third of L3.

Diffusion-weighted imaging (DWI) in musculoskeletal MRI: a critical review

Magnetic resonance imaging (MRI) is the mainstay of diagnosis, staging and follow-up of much musculoskeletal pathology. Diffusion-weighted magnetic resonance imaging (DWI) is a recent addition to the MR sequences conventionally employed. DWI provides qualitative and quantitative functional information concerning the microscopic movements of water at the cellular level. A number of musculoskeletal disorders have been evaluated by DWI, including vertebral fractures, bone marrow infection, bone marrow malignancy, primary bone and soft tissue tumours; post-treatment follow-up has also been assessed. Differentiation between benign and malignant vertebral fractures by DWI and monitoring of therapy response have shown excellent results. However, in other pathologies, such as primary soft tissue tumours, DWI data have been inconclusive in some cases, contributing little additional information beyond that gained from conventional MR sequences. The aim of this article is to critically review the current literature on the contribution of DWI to musculoskeletal MRI.

The value of lumbar spine magnetic resonance imaging in the demonstration of anular tears

Study Design. Retrospective review of magnetic resonance imaging and discography in patients investigated for low back pain before spinal fusion. Objective. To determine the sensitivity of magnetic resonance imaging in the detection of painful anular tears manifested by the high‐intensity zone. Summary of Background Data. Two studies have produced results showing that magnetic resonance imaging has a high specificity for the detection of painful anular tears manifested by a high‐intensity zone. However, in a recent study, results showed no significant correlation between the high‐intensity zone and pain reproduction. The sensitivity of magnetic resonance imaging in identifying anular tears in a symptomatic population has not been determined. Methods. Anular tears were identified in magnetic resonance images by the presence of a high‐intensity zone in the posterior anulus. The results were compared with the demonstration of painful anular tears on discogram, which has been considered the gold standard. Results. The study group comprised 58 patients (31 men, 27 women; mean age 42, range 21‐63 years). One hundred and fifty‐two discs were injected and examined by discography, and 108 were considered degenerate. Of these, 86 had anular tears (54 posterior, 6 anterior, 26 both). Seventy anular tears were associated with concordant pain provocation. Twenty‐seven high‐intensity zones were identified in magnetic resonance imaging, of which 24 were associated with pain reproduction by discography. The sensitivity, specificity, positive predictive value, and negative predictive value of magnetic resonance imaging in the diagnosis of concordantly painful posterior anular tears are therefore 26.7%, 95.2%, 88.9%, and 47%, respectively. Conclusion. These results confirm that the high‐intensity zone is a marker of a painful posterior anular tear. However, the usefulness of this sign is limited by low sensitivity.

Spinal cord infarction following therapeutic computed tomography-guided left L2 nerve root injection.

Study Design. Case report. Objectives. To report a rare case of spinal cord infarction following therapeutic computed tomography-guided nerve root injection. Summary of Background Data. Diagnostic and therapeutic image-guided nerve root injection is commonly performed in the management of low back pain and sciatica. The severe complication of spinal cord infarction has been reported in only 3 cases previously. Methods. Retrospective review of case records and imaging. Results. A 71-year-old woman presented with symptoms and signs of left L2 nerve root compression. She was managed with computed tomography-guided left L2 nerve root injection using bupivacaine and triamcinolone and developed immediate bilateral sensory loss and paraplegia. Magnetic resonance imaging demonstrated diffuse hyperintensity within the distal thoracic cord and conus on T2-weighted images, consistent with spinal cord infarction. Conclusions. We report the fourth case of spinal cord infarction following nerve root injection. The severity of this complication warrants that it should be considered during patient consent for this procedure.

Osteoid osteoma and osteoblastoma of the spine. Factors associated with the presence of scoliosis.

Study Design. A retrospective study of 44 museum cases of spinal osteoid osteoma or osteoblastoma and a meta‐analysis using 421 additional cases from a review of the literature. Objectives. To identify the factors that are associated with the development of scoliosis in these patients. Summary of Background Data. Painful scoliosis is a well‐recognized presentation of spinal osteoid osteoma and osteoblastoma and is considered to be secondary to pain‐provoked muscle spasm on the side of the lesion. Previous studies have been based on small numbers of patients that did not permit statistical validation of the reported observations. Methods. Eight factors were assessed including: age, gender, duration of symptoms, site of lesion in the spine, vertebral level of lesion, site of lesion in the individual vertebra, type of lesion, and Cobb angle at presentation. Reports were reviewed only if the presence or absence of scoliosis could be determined. Statistical analyses initially were performed on the museum cases and then on a combination of museum cases and cases from the literature. Results. Overall, 63% of subjects had scoliosis. The lesions were typically present on the concave aspect of the curve. Three cases of scoliosis from the literature involved lesions that were reported to be on the convexity. Scoliosis is significantly more common in cases of osteoid osteoma than in cases of osteoblastoma (P < 0.0001); lesions are more common in the thoracic and lumbar regions than in the cervical region (P < 0.0001), in lower cervical region than in the upper cervical region (P value = 0.0027), and they are more commonly located to one side of the midline (P < 0.0001). Age, gender, and duration of symptoms were of no significance. Conclusions. The findings support the concept that scoliosis is secondary to asymmetric muscle spasm in patients with spinal osteoid osteoma or osteoblastoma.

Pictorial review: The radiological investigation of lumbar spondylolysis

Lumbar spondylolysis represents a stress fracture of the pars interarticularis and occurs most commonly at the L5 level. Pars defects can be imaged with plain radiography, bone scintigraphy, computed tomography (CT) and magnetic resonance imaging (MRI). Plain radiographic projections of particular value include the coned lateral view of the lumbosacral junction, which displays the majority of defects, and the anteroposterior view with 30° cranial angulation. The value of oblique radiography is unproven. Planar bone scintigraphy (PBS) is more sensitive than radiography and single photon emission computed tomography (SPECT) more sensitive and specific than PBS. Both these techniques, however, are less specific than radiography and CT. CT, when performed with a reverse gantry angle and thin sections, is the investigation of choice for identifying radiographically occult lyses. Conventional lumbar spine MRI techniques are valuable for demonstrating normality of the pars, but may be associated with a high false positive rate for the diagnosis of pars defects.

Comparison of plain radiographs with CT scan to evaluate interbody fusion following the use of titanium interbody cages and transpedicular instrumentation.

The availability of lumbar interbody cages has fuelled renewed interest in interbody fusion. Despite this, there is no consensus regarding the best non-invasive method for evaluation of interbody fusion, especially where cages have been used. The purpose of this study was to determine whether high-quality thin-slice (1- to 3-mm) computed tomography (CT) scans allow proper evaluation of interbody fusion through titanium cages. Patients undergoing lumbar interbody fusion were prospectively evaluated with CT scan and plain radiographs 6 months following surgery. These images were blindly and independently evaluated by a consultant radiologist and a spine research fellow, for bridging bony trabeculation both through and surrounding the cages as well as for changes at the cage endplate interface. Fifty-three patients (156 cages) undergoing posterior lumbar interbody fusion using titanium interbody cages were evaluated. Posterior elements were used to pack the cages and no graft was packed outside the cages. The outcome data were analysed using the Kappa co-efficient and chi-squared analysis. On CT scan, both observers noted bridging trabeculation in 95% of the cages (Kappa 0.85), while on radiographs this was present in only 4% (Kappa 0.74). Both observers also identified bridging trabeculation surrounding the cages on CT scan in 90% of cages (Kappa 0.82), while on the radiographs this was 8% (Kappa 0.86). Radiographs also failed to demonstrate all the loose cages. The results of the study show that high-quality CT scans show images suggesting bridging bony trabeculae following the use of titanium interbody cages. They also appear to show consistent bone outside the cages in spite of no bone graft having been used, and they appear to be better than plain radiographs in the early detection of cage loosening.

Imaging of Intra-articular Osteoid Osteoma

Intra-articular osteoid osteoma accounts for approximately 13% of all osteoid osteomas and presents as a monoarthropathy. Radiographs commonly do not identify the nidus, and in this event, MRI is likely to be the next imaging investigation. MRI may show a variety of appearances depending upon the age of the lesion. This article illustrates the imaging features of intra-articular osteoid osteoma, with emphasis on MRI. CT remains the investigation of choice for identifying the nidus.

Upright positional MRI of the lumbar spine.

Supine magnetic resonance imaging (MRI) is routinely used in the assessment of low back pain and radiculopathy. However, imaging findings often correlate poorly with clinical findings. This is partly related to the positional dependence of spinal stenosis, which reflects dynamic changes in soft-tissue structures (ligaments, disc, dural sac, epidural fat, and nerve roots). Upright MRI in the flexed, extended, rotated, standing, and bending positions, allows patients to reproduce the positions that bring about their symptoms and may uncover MRI findings that were not visible with routine supine imaging. Assessment of the degree of spinal stability in the degenerate and postoperative lumbar spine is also possible. The aim of this review was to present the current literature concerning both the normal and symptomatic spine as imaged using upright MRI and to illustrate the above findings using clinical examples.