Lumbar Disc Degeneration

Computed tomography (CT) images of 59 discs in 30 patients suffering from low back pain were compared with CT/discography images of the same discs in order to assess the correlation between intradiscal damage and changes in annular configuration and density. The discs were graded in CT as not bulging, slight protrusion, advanced protrusion or disc herniation, and were checked for local areas of hypodensity. General degeneration and annular disruption in CT/discography were evaluated separately according to the Dallas Discogram Description, on a scale of non-existent, slight, moderate, or severe. Most discs with a slight protrusion in CT showed severe annular disruption in CT/discography. Discs with advanced protrusion showed in addition a severe general degeneration. Disc herniation was associated only with severe annular disruption. Local hypodensity proved to be a specific but insensitive sign of annular disruption. It is concluded that a bulging disc is a sign of intradiscal damage and should be noted even when there is no nerve entrapment present.

Traumatic Trabecular Lesions Observed on MR Imaging of the Knee

Examinations carried out on 302 consecutive patients with MR of the knee between January 1988 and March 1989 were reviewed for detection of trabecular lesion. Twenty-seven patients found presenting trabecular lesion were further reviewed with specific reference to their activity level and need for specific therapy to determine the clinical significance of the trabecular lesion. Twenty-one of the trabecular lesions were in the femur, 5 were in the tibia, and one was in the fibula. Three of them were associated with a direct trauma, 12 with a valgus type injury, 3 with pure rotation mechanism, and 5 with a combination of valgus and rotation. In 17 cases trabecular lesion was a single finding, in 10 cases it was associated with some ligamentous tear. At the follow-up visit, 26 of the 27 patients with trabecular lesion had no symptoms, and the patient with moderate knee symptoms had had similar knee symptoms prior to the accident due to an osteochondral defect. We conclude that a trabecular lesion in an MR image is a benign bone change associated with knee trauma which heals without sequelae.

Apparent diffusion coefficients and T2 relaxation time measurements to evaluate disc degeneration: A quantitative MR study of young patients with previous vertebral fracture

Purpose: To assess the suitability of apparent diffusion coefficient (ADC) measurements to evaluate degeneration processes of the vertebral disc and to compare the results with T2 relaxation time measurements in both degenerated and normal intervertebral discs.

Material and Methods: Fourteen young patients (8.8-20.8 years old) who had had a vertebral compression fracture at least 1 year earlier, underwent MR studies with diffusion imaging in three orthogonal directions and T2 relaxation time measurements. ADC values and T2 relaxation times of both degenerated and normal intervertebral discs were compared to the values of 20 healthy young asymptomatic control subjects.

Results: In the degenerated discs of patients, the ADCx and ADCy values were decreased compared to earlier determined values of healthy controls. ADC values in the z-direction in degenerated discs did not differ significantly from the values of controls. T2 relaxation times were shorter in the degenerated discs of patients compared to the values of controls. The greatest changes in both these values were observed in degenerated discs followed by discs with normal signal intensity adjacent to primary trauma area and secondary trauma area.

Conclusion: We suggest that decreased ADC values reflect the lost integrity of the intervertebral disc. ADC measurements at MR may prove sensitive depicting of early degenerative changes in vertebral discs.

Imaging and estimation of the prognostic features of primary sclerosing cholangitis by ultrasonography and MR cholangiography

Purpose: To evaluate the ability of US and MR cholangiography (MRC) to detect bile duct changes and prognostic signs of primary sclerosing cholangitis (PSC) seen at endoscopic retrograde cholangiography (ERC).

Material and Methods: In a prospective study, 9 patients with PSC underwent US, MRC, MR imaging and ERC of the bile ducts and the liver. Eight age- and sex-matched control patients were examined with MRC, MR imaging and ERC. A segmental comparison was performed to assess the ability of MRC-MR and US to reveal the accurate ductal involvement in different segments of the biliary tree and the specific criteria of poor prognostic outcome in PSC. The ability of MRC-MR to detect the presence of PSC in different patients was analysed blindly.

Results: MRC-MR depicted changes of PSC correctly in 9 patients (radiologist 1) and in 8 patients with 1 false-positive finding (radiologist 2) in the blinded analysis. In the segmental comparison, MRC missed especially bile duct dilatations. MRC was too pessimistic in the evaluation of the outcome. US detected features suggestive of PSC in 8 patients (radiologist 3). US was unable to show the predictors of poor outcome.

Conclusion: MRC and US seem to be useful in the detection of PSC. US is unable and MRC is too pessimistic to estimate the outcome of PSC.

The efficacy of a continuous quality improvement (CQI) method in a radiological department: Comparison with non-CQI control material

Objective: To study the efficacy of continuous quality improvement (CQI) compared to ordinary management in an on-duty radiology department.

Material and Methods: Because of complaints regarding delivery of on-duty radiological services, an improvement was initiated simultaneously at two hospitals, at the HUCH (Helsinki University Central Hospital) utilising the CQI-method, and at the OUH (Oulu University Hospital) with a traditional management process. For the CQI project, a team was formed to evaluate the process with flow-charts, cause and effect diagrams, Pareto analysis and control charts. Interventions to improve the process were based on the results of these analyses.

Results: The team at the HUCH implemented the following changes: A radiologist was added to the evening shift between 15:00-22:00 and a radiographer was moved from the morning shift to 15:00-22:00. A clear improvement was achieved in the turn-around time, but in the follow-up some of the gains were lost. Only minimal changes were achieved at the OUH, where the intervention was based on traditional management processes.

Conclusion: CQI was an effective method for improving the quality of performance of a radiology department compared with ordinary management methods, but some of this improvement may be subsequently lost without a continuous measurement system.

Comparison between DICOM-calibrated and uncalibrated consumer grade and 6-MP displays under different lighting conditions in panoramic radiography

OBJECTIVES

To compare observer performance in the detection of anatomical structures and pathology in panoramic radiographs using consumer grade with and without digital imaging and communication in medicine (DICOM)-calibration and 6-megapixel (6-MP) displays under different lighting conditions.

METHODS

30 panoramic radiographs were randomly evaluated on three displays under bright (510 lx) and dim (16 lx) ambient lighting by two observers with different years of experience. Dentinoenamel junction, dentinal caries and periapical inflammatory lesions, visibility of cortical border of the floor and pathological lesions in maxillary sinus were evaluated. Consensus between the observers was considered as reference. Intraobserver agreement was determined. Proportion of equivalent ratings and weighted kappa were used to assess reliability. The level of significance was set to p < 0.05.

RESULTS

The proportion of equivalent ratings with consensus differed between uncalibrated and DICOM-calibrated consumer grade displays in dentinal caries in the lower molar in dim lighting (p = 0.021) and between DICOM-calibrated consumer grade and 6-MP display in bright lighting (p = 0.038) for an experienced observer. Significant differences were found between uncalibrated and DICOM-calibrated consumer grade displays in dentinal caries in bright lighting (p = 0.044) and periapical lesions in the upper molar in dim lighting (p = 0.008) for a less experienced observer. Intraobserver reliability was better at detecting dentinal caries than at detecting periapical and maxillary sinus pathology.

CONCLUSIONS

DICOM calibration may improve observer performance in panoramic radiography in different lighting conditions. Therefore, a DICOM-calibrated consumer grade display can be used instead of a medical display in dental practice without compromising the diagnostic quality.

Justification of CT examinations in young adults and children can be improved by education, guideline implementation and increased MRI capacity

OBJECTIVE

To determine whether the justification of CT examinations performed on young patients can be improved by various interventions and whether these have an effect on the total number of CTs performed.

METHODS

Specific interventions-education, guideline implementation and increased MRI capacity-were introduced at the Oulu University Hospital, Oulu, Finland, following a previous study demonstrating unjustified use of CT examination in young patients. In the present study, the justification of 177 CT examinations of the lumbar and cervical spine, head, abdomen, nasal sinuses and trauma performed on patients aged under 35 years in 2009 was analysed retrospectively by looking at requests and corresponding patient files. The indications of the examinations were compared with the referral guidelines recommended by the European Commission. Results from our previously published similar study carried out before the interventions were used as a reference.

RESULTS

The proportion of justified CT examinations increased from 71% (141/200) in 2005 to 87% (154/177) in 2009 (p<0.001), and in the lumbar spine group from 23% (7/30) to 81% (22/27) (p<0.001). In the case of most of the unjustified examinations, MRI could have been performed instead. The total number of CT examinations carried out on young patients decreased by 7% (p=0.012) and in the lumbar spine group by 79% (p<0.001).

CONCLUSION

The implemented interventions decreased the number of CT examinations performed on young patients, and the justification of the examinations improved significantly.

ADVANCES IN KNOWLEDGE

This study demonstrates that it is possible to reduce the number of various CT examinations and to improve their justification in young patients by regular education, guideline implementation and increased MRI capacity.

MRI FINDINGS AFTER AN EXPERIMENTAL DISC LESION

Purpose: A minipig model was used to demonstrate MRI findings in the first three months after an annular disruption. Methods: An incision was made into one of the lumbar discs in each of eight minipigs in the outer and middle parts of the annulus. The remaining intact discs in the lumbar and thoracolumbar regions were used as controls. MR imaging was performed one month and three months after trauma using both a 1.0 T and a 1.5 T MR unit. The histologic analysis was also carried out to demonstrate morphological changes in disc. Results: Eighty-eight percent of the injured discs had a diminished area of bright signal in the nucleus pulposus, also in cases where no signs of trauma in the annulus could be detected in MRI. The degeneration process of the nucleus pulposus was shown to progress during follow-up. High intensity zones were detected in 50% of the injured discs and they tended to appear already after one month follow-up. Histological examination showed that the high-intensity zone contained clusters of nuclear cells originating in the nucleus pulposus. Conclusion: It is concluded that lesions producing high-intensity zones can be induced in an experimental animal model and it can already be detected one month after the trauma. Degeneration process of the nucleus is generally initiated after a peripheral annular lesion.

Topographical variation of T2 relaxation time in the young adult knee cartilage at 1.5 T

OBJECTIVE

To assess the normal topographical variation of T2 relaxation time of articular cartilage in different compartments of the knee joint and at different tissue depths in young healthy adults.

METHODS

Twenty asymptomatic young adult volunteers (age range, 21-27 years; mean age, 22.5 years), were studied at 1.5T. Both axial and sagittal multi-slice multi-echo spin echo measurements were performed to determine the T2 relaxation time of cartilage in the femoral, tibial and patellar compartments. The cartilage surfaces were divided into 24 segments and each segment was divided into deep and superficial regions-of-interest (ROIs) of equal thickness. The reproducibility for ROI analysis was assessed for five patients by determining the interclass correlation coefficient (ICC) and the root-mean-square coefficient of variation (CV(RMS)).

RESULTS

Cartilage T2 was significantly dependent on joint topography, compartment and tissue depth. For all joint surfaces, superficial T2 values were systematically higher as compared to deep tissue. The data showed a trend toward higher T2 values at the load bearing area of the femoral condyles. The interobserver error varied significantly among different locations and showed mostly good reproducibility with mean ICC of 0.70 and a CV(RMS) of 5.0%.

CONCLUSION

The normal variation in cartilage T2 within a joint is significant and should be acknowledged when pathology-related T2 changes are investigated. The knowledge on normal variation can be used for power and sample size calculations in further studies, and the T2 values as control data in future patient studies.

Association of lumbar arterial stenosis with low back symptoms: a cross-sectional study using two-dimensional time-of-flight magnetic resonance angiography

BACKGROUND

Recent studies indicate that diminished blood flow may cause low back symptoms and intervertebral disc degeneration.

PURPOSE

To explore the association between lumbar arterial stenosis as detected by two-dimensional time-of-flight magnetic resonance angiography (2D TOF-MRA) and lumbar pain symptoms in an occupational cohort of middle-aged Finnish males.

MATERIAL AND METHODS

228 male subjects aged 36 to 55 years (mean 47 years) were imaged with 2D TOF-MRA. Additionally, 20 randomly selected subjects were scanned with contrast-enhanced MRA (ceMRA). In each subject, the first (L1) to fourth (L4) segmental lumbar arteries were evaluated for lumbar artery stenosis using a dichotomic scale. One subject was excluded because of poor image quality, reducing the study population to 227 subjects. Logistic regression analysis was used to evaluate the association between arterial stenosis in 2D TOF-MRA and low back pain and sciatica symptoms (intensity, duration, frequency).

RESULTS

Comparing 2D TOF-MRA and ceMRA images, the kappa value (95% confidence interval) was 0.52 (0.31-0.73). The intraobserver reliability kappa value for 2D TOF-MRA was 0.85 (0.77-0.92), and interobserver kappa was 0.57 (0.49-0.65). The sensitivity of 2D TOF-MRA in detecting stenosis was 0.58, the accuracy 0.89, and the specificity 0.94. In 97 (43%) subjects all arteries were normal, whereas 130 (57%) had at least one stenosed artery. The left L4 artery was most often affected. The degree of arterial stenosis was associated with intensity of low back and sciatic pain, and sciatica pain duration during the past 3 months.

CONCLUSION

2D TOF-MRA is an acceptable imaging method for arterial stenosis compared to ceMRA. Arterial stenosis was associated with subjective pain symptoms, indicating a role of decreased nutrition in spinal disorders.

Chronic hydrocephalus after neurosurgical and endovascular treatment of ruptured intracranial aneurysms

BACKGROUND

Chronic hydrocephalus is a common sequela of subarachnoid hemorrhage (SAH). The technical procedure used to treat intracranial aneurysms, whether neurosurgical clipping or endovascular coiling, may lead to differences in the incidence of chronic posthemorrhagic hydrocephalus.

PURPOSE

To compare the effects of early neurosurgical and early endovascular treatment on the development of chronic hydrocephalus in patients with SAH.

MATERIAL AND METHODS

A retrospective study included 102 clipped and 107 coiled patients with aneurysmal SAH. Clinical condition at admission and shunt dependence were verified from patient data records. The initial and follow-up computed tomography (CT) images were reviewed, and the amount and distribution of blood and the occurrence of hydrocephalus were registered. The values of the cella media index and the width of the third ventricle were calculated. Statistical analysis of the data was performed.

RESULTS

No statistically significant differences in the incidence of chronic hydrocephalus or the need for shunting emerged between the treatment groups. After clipping 35% and after coiling 39% of the patients developed chronic hydrocephalus. Twenty-nine percent of the clipped and 31% of the coiled patients underwent a shunt operation.

CONCLUSION

The treatment method used for acutely ruptured intracranial aneurysms, i.e., neurosurgical clipping or endovascular coiling, has no statistically significant effect on the development of chronic hydrocephalus.

Quantitative magnetic resonance imaging of experimentally injured porcine intervertebral disc

BACKGROUND

Changes in T2 relaxation time (T2-TR) and apparent diffusion coefficients (ADC) have been suggested to appear in the intervertebral disc before morphological changes. Such sensitive imaging methods could be beneficial in the targeting and follow-up of intradiscal gene therapy.

PURPOSE

To investigate the sensitivity of quantitative magnetic resonance (MR) imaging methods (T2-TR and ADC) in early disc degeneration, using an experimental porcine intervertebral disc injury model, and to investigate their sensitivity in depicting biochemically controlled degenerative changes in the disc.

MATERIAL AND METHODS

Six juvenile pigs underwent experimental annular stab incisions, one superficial and one reaching the nucleus pulposus. The animals underwent repeated 1.5T MR imaging and were sacrificed 4 or 8 weeks after operation. Presence of degenerative changes was controlled with biochemical analysis.

RESULTS

Discs with full-thickness annular incisions lost 30% of their sagittal mid-slice nucleus pulposus area in 2 weeks (P<0.05). T2-TRs of the respective discs were on average 73% of the control discs (P<0.05). Discs with full-thickness annular lesions showed increased ADC values 4 weeks and reduced ADC values 8 weeks after the operation, compared to control discs (P<0.05). Biochemical analysis showed changes consistent with early degeneration.

CONCLUSION

Early traumatic or degenerative changes are detectable with both T2-TR and ADC. The ADC in the early phase after experimental trauma seems to initially increase before decreasing.

Patellar cartilage lesions: comparison of magnetic resonance imaging and T2 relaxation-time mapping

PURPOSE

To evaluate the detection and the size of focal patellar cartilage lesions in T2 mapping as compared to standard clinical magnetic resonance imaging (MRI) at 1.5T.

MATERIAL AND METHODS

Fifty-five consecutive clinical patients referred to knee MRI were imaged both with a standard knee MRI protocol (proton-density-weighted sagittal and axial series, T2-weighted sagittal and coronal series, and T1-weighted coronal series) and with an axial multislice multi-echo spin-echo measurement to determine the T2 relaxation time of the patellar cartilage. MR images and T2 maps of patellar cartilage were evaluated for focal lesions. The lesions were evaluated for lesion width (mm), lesion depth (1/3, 2/3, or 3/3 of cartilage thickness), and T2 value (20-40 ms, 40-60 ms, or 60-80 ms) based on visual evaluation.

RESULTS

Altogether, 36 focal patellar cartilage lesions were detected from 20 human subjects (11 male, nine female, mean age 40+/-15 years). Twenty-eight lesions were detected both on MRI and T2 maps, while eight lesions were only visible on T2 maps. Cartilage lesions were significantly wider (P = 0.001) and thicker (P<0.001) on T2 maps as compared to standard knee MRI. Most lesions 27 had moderately (T2 40-60 ms) increased T2 values, while two lesions had slightly (T2 20-40 ms) and seven lesions remarkably (T2 60-80 ms) increased T2 relaxation times.

CONCLUSION

T2 mapping of articular cartilage is feasible in the clinical setting and may reveal early cartilage lesions not visible with standard clinical MRI.

Reliability of the evaluation of multidetector computed tomography images from the scanner's console in high-energy blunt-trauma patients

PURPOSE

To evaluate the reliability of a structured 5-min evaluation of multidetector computed tomography (MDCT) images from the scanner's console in high-energy trauma patients.

MATERIAL AND METHODS

Forty patients were scanned with four-slice MDCT using a standardized trauma protocol. Image evaluation covered the thorax, abdomen, and pelvis. The radiologist scrolled axial images on the scanner's console using three different window settings (lung, soft tissue, and bone) and performed a prospective structured evaluation of the traumatic lesions. The findings were compared to the final radiological diagnosis of the MDCT data made on a PACS workstation, the operative findings, and the clinical follow-up.

RESULTS

Evaluation from the scanner's console enabled the diagnosis of all potential life-threatening injuries, the sensitivity for all injuries being 60% and specificity 98%.

CONCLUSION

A PACS workstation is needed for the final diagnosis of all injuries, but this rapid screening method can reliably detect all injuries that require instant care.

Cost analysis of an open low-field (0.23T) MRI unit: effect of procedure shares in combined imaging, interventional, and neurosurgical use

PURPOSE

To analyze the cost structure of procedures performed in a multipurpose interventional magnetic resonance imaging (IMRI) unit and to analyze the effect of procedure shares on cost structure.

MATERIAL AND METHODS

During a 1-year period, 691 procedures were performed in the IMRI unit, of which 563 were diagnostic MRI examinations, 89 MRI-guided interventions, and 39 MRI-guided neurosurgical operations. Three alternative utilization models of IMRI were created to simulate different local institutions by adjusting the proportions of different procedures. The costs of procedures were calculated by activity-based cost analysis.

RESULTS

The cost of the main procedure (imaging, biopsy, injection, or operation) was the most significant item in all procedures, accounting for 66-89% of the total costs. The volume of imaging has a major effect on unit costs. Volume is not such a deterministic factor in interventions due to the high material costs. The volume of neurosurgical use of IMRI has a major effect on the costs of radiological procedures due to the long operation times.

CONCLUSION

The volumes of different procedures done on an IMRI unit have significant effects on the unit costs of the procedures.

Cost comparison of low-field (0.23 T) MRI-guided laser ablation and surgery in the treatment of osteoid osteoma

The purpose of this study was to analyze the costs of magnetic resonance imaging (MRI)-guided laser ablation and to compare them with the costs of surgery in the treatment of osteoid osteoma. Seven patients with osteoid osteoma were treated with MRI-guided interstitial laser ablation during 1 year. The reference material consisted of six patients whose osteoid osteoma was treated surgically by either superficial or deep excision with metallic fixation. The costs were analyzed by using activity-based cost accounting. The mean cost of the MRI-guided laser ablation was 2,392 euros and of the excision of superficially located osteoid osteoma 1,807 euros. The cost of excision of deeply located osteoma with metallic fixation was considerably higher (4,996 euros). This was due to the higher material, personnel, and ward costs. The cost of MRI-guided laser ablation of osteoid osteoma was higher than the cost of surgical excision of a superficial osteoma but considerably lower than the cost of excision of a deeply located osteoma where metallic fixation was needed. When the number and mean cost of sick days or days of restricted weight bearing were also included, the cost of MRI-guided laser ablation was lower than the costs of either superficial or deep excision.

Magnetic resonance imaging-guided diskography and diagnostic lumbar 0.23T MRI: an assessment study

PURPOSE

To describe the in vivo appearance of magnetic resonance imaging (MRI) diskograms of normal and degenerated lumbar intervertebral disks, and to evaluate the differences in imaging findings between sequential diagnostic MRI and MRI diskography.

MATERIAL AND METHODS

Nine consecutive patients underwent MRI-guided diskography in order to determine possible pain provocation during puncture and contrast medium injection. All patients had preceding clinical suspicion of lumbar diskogenic pain and findings of lumbar disk degeneration in diagnostic (MRI, computed tomography (CT), plain radiography). A 0.23T open MRI scanner with interventional tools was used for imaging and instrument guidance. On all patients, a complementary diagnostic MRI study of the lumbar spine before and after the MRI-guided disk injection was performed, and subsequent axial MRI diskograms were obtained.

RESULTS

A total of 25 disk punctures were initialized, and 25 MRI diskograms were obtained and their expression described. There was a correlation between the degenerative disk findings visualized by diagnostic MRI and MRI diskograms.

CONCLUSION

The use of gadolinium contrast media in MRI-guided diskography enables the evaluation of MRI diskograms. Our results suggest that MRI-guided diskography can be used to substitute conventional diskography or CT-diskography and as an augmenting method to assess diagnostic information upon degenerative processes of the lumbar spine.

MR-guided interventional procedures: a review

Magnetic resonance imaging (MRI) has emerged as a potential guidance tool for a variety of procedures. Diagnostic and therapeutic procedures using either open surgical or percutaneous access are performed. They span from simple lesion targeting and biopsy to complex applications requiring multiple tasks performed simultaneously or in rapid succession. These tasks include instrument guidance and therapy monitoring as well as procedural follow-up. The interventional use of MRI (IMRI) is increasing steadily. This article reviews the prerequisites, systems, and clinical interventional procedures of IMRI.

Value of multidetector computed tomography in assessing blunt multitrauma patients

PURPOSE

To find out if multidetector computed tomography (MDCT), using a dedicated trauma protocol, provides sufficient diagnostic information of the injuries of blunt multitrauma patients to enable the planning of treatment for all body compartments.

MATERIAL AND METHODS

One-hundred-and-thirty-three patients exposed to high-energy trauma were referred and scanned with the standardized MDCT multitrauma protocol. The imaging protocol consisted of axial scanning of the head and helical scanning of the facial bones, cervical spine, thorax, abdomen, and pelvis. The scanning times were 12 s for the head, 19-21 s for the facial bones and cervical spine (1 mm collimation), and 32-50 s for the thorax, abdomen, and pelvis (2 mm collimation). One-hundred-and-forty milliliters of non-iodinated contrast material (300 mg I/ml) was administered intravenously at 3 ml/s.

RESULTS

Ninety-nine of the patients (74%) had at least one finding consistent with trauma. The most frequent findings were in the thorax in 58 patients (44%). Nineteen false-negative findings and two false-positive findings were made. The overall sensitivity of MDCT was 94%, specificity 100%, and accuracy 97%.

CONCLUSION

MDCT is accurate in the assessment of blunt multitrauma patients. The decision to treat the patient can be made on the basis of MDCT with a reasonable level of certainty.

MRI-guided abdominal biopsy in a 0.23-T open-configuration MRI system

The purpose of this study was to test the hypothesis that when ultrasound (US) guidance is not feasible, abdominal biopsies can be performed safely and accurately under magnetic resonance imaging (MRI) guidance in a low-field environment. MRI-guided abdominal biopsy was performed on 31 consecutive patients, in whom US-guided abdominal biopsy was not possible because the lesion was not visualized in US (n=27) or an US-guided procedure was not considered safe (n=4). The locations of the lesions were liver (n=14), pancreas (n=6), lymph node (n=4), retroperitoneal mass (n=3), adrenal gland (n=3) and spleen (n=1). The average size of the lesion was 2.2 cm (range 1-4 cm) in maximum diameter. All procedures were done by using a 0.23-T open-configuration C-arm-shaped MRI scanner with interventional optical tracking equipment and software. Fine-needle aspiration (FNA) biopsy was performed on all 31 patients; 18 patients underwent both FNA biopsy and cutting needle core biopsy. Procedures were evaluated for diagnostic sensitivity, specificity and accuracy as well as procedure time and complications. The FNA biopsy specimens were adequate for interpretation in 27 (87%) of 31 cases. Two of these proved to be false-negative findings during follow-up or subsequent biopsy. The final diagnosis was malignant in 15 and benign in 16 patients. The sensitivity, specificity and accuracy of FNA biopsy were 71, 100 and 81%, respectively. Of the 18 core-needle biopsies, one was determined false-negative owing to nonrepresentativeness. The sensitivity, specificity and accuracy of histological samples were 90, 100 and 94%, respectively. The needle time was 19 min on average and the mean room time was 1 h 48 min. No immediate or late complications occurred. MRI-guided abdominal biopsy can be performed safely and accurately in a low-field environment in patients for whom an US-guided procedure is not feasible.

Contrast-enhanced dynamic and static MRI correlates with quantitative 99Tcm-labelled nanocolloid scintigraphy. Study of early rheumatoid arthritis patients

OBJECTIVE

The aim of this study was to evaluate the roles of contrast-enhanced dynamic and static magnetic resonance imaging (MRI) and quantitative 99Tcm-labelled nanocolloid (NC) scintigraphy in detecting wrist joint inflammation in early rheumatoid arthritis (RA) patients.

METHODS

Twenty-eight early RA patients (median symptom duration 5 months, range 1-12 months) underwent MRI, NC scintigraphy, laboratory and clinical examinations. Static wrist MRI scans were retrospectively scored for synovitis, bone oedema and erosions by two independent readers using the recently published rheumatoid arthritis MRI scoring system (RAMRIS). Twenty NC scans were analysed quantitatively by measuring maximum 99Tcm-NC uptake in three small areas of each wrist. From the same locations on the wrists, dynamic MRI gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA) enhancement rates (E-rate) were measured. The average 99Tcm-NC uptake of the whole wrist region was also measured and average E-rates were calculated. Correlations between MRI and NC scintigraphy measurements were calculated. Correlations between imaging methods of the wrist and the global measures of inflammation (laboratory and clinical examinations) were also assessed.

RESULTS

Strong correlations emerged between maximal 99Tcm-NC uptake and MRI E-rates, reflecting similar performance of the methods in detecting local synovial inflammation. 99Tcm-NC uptake and MRI E-rate correlated with semiquantitative scoring of synovitis and bone oedema from static MRI scans. The erythrocyte sedimentation rate (ESR) correlated with MRI scores, E-rate and 99Tcm-NC uptake. No correlation between the clinical parameters and the imaging methods was detected. Inter-observer reliability for scoring synovial hypertrophy, bone oedema and bone erosions from static MR images were high (single-measure fixed-effects intra-class correlations 0.87, 0.93 and 0.91 respectively). Intra-observer reliability for E-rate and 99Tcm-NC measurements of 10 randomly picked scans was found to be high, with an intra-class correlation of 0.92; 95% confidence interval (CI) 0.84-0.96 and 0.99; 95% CI 0.98-1.00, respectively.

CONCLUSIONS

Objective information about wrist joint inflammation can be obtained with contrast-enhanced dynamic MRI and quantitative 99Tcm-labelled NC scintigraphy. MRI also allows visualization and semiquantitative scoring of bone oedema and erosions of the wrist. Dynamic MRI and NC scintigraphy are safe and easy to perform, and they can be used in a long-term follow-up of rheumatoid patients.

Cost comparison analysis of low-field (0.23 T) MRI- and CT-guided bone biopsies

The aim of this study was to analyze and compare the costs of low-field (0.23 T) MRI- and CT-guided bone biopsies. The cost comparison consisted of 18 MRI-guided and 12 CT-guided bone biopsies performed during a 1-year period. The costs and activities of these two methods were analyzed by using activity-based cost accounting (ABC). The costs of MRI-guided bone biopsy (1205 Euro) were 2.55-fold compared with those of the CT-guided bone biopsy (472 Euro). The higher costs of the biopsy procedure in MRI were due to the higher material (5.57-fold) and personnel (2.73-fold) costs. The MRI-guided bone biopsies proved to be considerably more expensive than CT-guided bone biopsies. This was due to the higher material costs, especially the highly priced MRI compatible instrumentation and the longer procedure time. The MRI guidance in performing bone biopsies should be justified on the basis of the better accuracy and the lack of radiation. Evaluations of cost-effectiveness concerning MRI-guided bone biopsy are needed.

Cross-sectional survey of paranasal sinus magnetic resonance imaging findings in schoolchildren

AIM

Sinus image abnormalities are common among children examined for indications other than sinus disease. The purpose of this study was to determine the frequency of sinus abnormalities among otherwise healthy children attending school.

METHODS

Magnetic resonance imaging (MRI) was performed on 24 children aged 8-9 y, 18 of whom were re-examined after 6-7 mo.

RESULTS

Sinus abnormalities were common. An abnormality was seen in 12 of the children [50%, 95% confidence interval (95% CI) 29-71%], and 9 (38%, 95% CI 19-59%) had abnormalities in the maxillary sinuses. As many as 8 (42%, 95% CI 20-67%) of the asymptomatic children (lacking clinical symptoms or findings) had abnormalities in the maxillary or ethmoidal sinuses. The follow-up examination showed that about half of the abnormal sinus MRI findings had resolved or improved without any intervention.

CONCLUSION

Abnormal sinus MRI findings are common both among otherwise healthy children attending school and in totally asymptomatic children. As incidental findings, these should be interpreted as normal and do not indicate any need for treatment in children imaged for purposes other than sinus disease.

Acute bilateral exercise-induced medial compartment syndrome of the thigh. Correlation of repeated MRI with clinicopathological findings

We present a case report of acute bilateral excercise-induced compartment syndrome in the adductor longus muscles, which was treated with bilateral medial fasciotomies. Postoperatively, the healing process of the adductor muscles was followed up by repeated MR imagings over six months. Myonecrosis was found in peroperative muscle biopsies. Pain and muscle swelling subsided soon after the fasciotomy, correlating with the early postoperative MR findings. Four months postoperatively, the signal intensity of the adductor muscles was normal in T1- and T2-weighted images, but the normal fibre structure of the adductor muscles could only be seen 6 months postoperatively. At six month's control checkup there was no subjective weakness of the adductors, and hyperesthesia had disappeared and the patient was capable of normal activities.

Versatile intraoperative MRI in neurosurgery and radiology

BACKGROUND

Several models for the application of intra-operative magnetic resonance imaging (IMRI) have recently been reported, most of them unique. Two fundamental issues need to be addressed: optimal use of the scanner to ensure a wide base for research, development and clinical application, and an organisational model that facilitates such use.

METHOD

While in our setting the IMRI project was initiated by the neurosurgeons, the need for wider use of the facilities was recognised since the beginning of the planning phase in 1996. An organisational model was developed that allowed for development of neurosurgical applications, radiological imaging, and radiological interventions and for the research and development work of the vendor. A resistive 0.23 T MR scanner was installed in a dedicated operating room environment. Unique to this scanner is the ability to turn off the magnet, allowing for normal OR activities and devices, and to turn on the magnet as needed with a relatively short six-minute ramp up time. A staged surgical technique was perfected, allowing for transfer of data to the neuronavigator outside the scanner during surgery. In neurosurgery, IMRI was used as one part of a neuronavigational system that included ultrasound imaging, intra-operative cortical stimulation during awake procedures, electrocorticography and two neuronavigators.

FINDINGS

34 neurosurgical cases included 27 brain tumour resections, 5 brain tumour biopsies, 1 extirpation of an arterio-venous malformation, and 1 haematoma evacuation. The scanner could also be used for normal clinical imaging where obese patients, children, claustophobic patients and postoperative control examinations were the major groups. The radiologists performed 110 interventions, including bone and abdominal biopsies, nerve root infiltrations and local pain therapies, with the optical needle tracking system under continuous MRI guidance. The organisational model allowed frequent use of the facilities for both neurosurgery and radiology and continuous development of the facilities. Intra-operative ultrasound was used in 20 tumour resections and in two open brain biopsies. This resulted in reduction of the number of MR imaging sessions during surgery. Five of the 27 resections were performed as awake craniotomies with cortical stimulation. For two of the resections, electrocorticography and depth electrode registrations were used. Furthermore, various non-MRI-compatible instruments and devices were used.

INTERPRETATION

Intra-operative MRI is an imaging tool that can be useful especially in the context of neuronavigation. A scanner that can be turned off during surgery is particularly appropriate for neurosurgery. The concept of joint use of such facilities with other clinicians is mutually worthwhile.

Sacro-iliac joint arthrography in low back pain: feasibility of MRI guidance

OBJECTIVE

Evaluation of the feasibility of MR-guidance in sacro-iliac joint arthrography in patients whose low back pain is suspected to arise from the sacro-iliac joint (SIJ).

METHODS AND PATIENTS

Twenty patients with low back pain underwent MR-guided sacro-iliac joint arthrography. Needles made from titanium (size 20 G, MDTech, USA) were used. For image guidance a 0.23T open-configuration C arm magnet (Proview, Marconi Medical Systems, USA) with special interventional hardware and software package (I-Path 200, Marconi Medical Systems) containing an MR compatible in-room console, large-screen (36") display, optical navigator and accompanying software with dedicated sequences was used. No other image guidance modalities were used.

RESULTS

MR-guided SIJ arthrography was successfully performed in all twenty patients without complications. The optimal imaging sequence both for preoperative and intraoperative images was 3D-Gradient Echo sequence. The dispersal of the injected saline and anaesthetic could be determined inside the joint in all cases with heavily T2-weighted fast spin echo sequence. In the present study, 60% of the patients had significant reduction of pain after sacro-iliac joint arthrography and sacro-iliac joint was considered to be the source of patients low back pain in these patients.

CONCLUSION

The present study shows that MR guidance with open configuration low field scanner is an accurate guiding method for sacro-iliac joint arthrography.

Cost effectiveness of periradicular infiltration for sciatica: subgroup analysis of a randomized controlled trial

STUDY DESIGN

A subgroup analysis of a prospective, randomized controlled trial was performed.

OBJECTIVE

To describe the cost effectiveness of periradicular infiltration with steroid in subgroups of patients with sciatica.

SUMMARY OF BACKGROUND DATA

A recent trial on periradicular infiltration indicated that a methylprednisolone-bupivacaine combination had a short-term effect, as compared with that of saline. This report describes the efficacy and cost effectiveness of steroid in subgroups of patients with sciatic.

METHODS

This study involved 160 patients with unilateral sciatica. Outcome assessments were leg pain (100-mm visual analog scale), disability on the Oswestry Low Back Disability Questionnaire, and the Nottingham Health Profile. Data on medical costs and sick leaves also were gathered. Patients were randomized for periradicular infiltration with either methylprednisolone-bupivacaine or saline. The adjusted between-group treatment differences at each follow-up assessment, the number of patients free of leg pain (responders, cutoff 75%), and efficacy by the area-under-the-curve method were calculated. For the cost-effectiveness estimate, the total costs were divided by the number of responders. The rate of operations in different subgroups was evaluated by Kaplan-Meier analysis.

RESULTS

In the case of contained herniations, the steroid injection produced significant treatment effects and short-term efficacy in leg pain and in Nottingham Health Profile emotional reactions. For symptomatic lesions at L3-L4-L5, steroid was superior to saline for leg pain, disability, and straight leg raising in the short term. By 1 year, steroid seemed to have prevented operations for contained herniations, costing $12,666 less per responder in the steroid group (P < 0.01). For extrusions, steroid seemed to increase the operation rate, and the steroid infiltration was more expensive, costing $4445 per responder (P < 0.01).

CONCLUSIONS

In addition to short-term effectiveness for contained herniations and lesions at L3-L4-L5, steroid treatment also prevented surgery for contained herniations. However, steroid was countereffective for extrusions. The results of the subgroup analyses call for a verification study.

Correlation of diffusion in lumbar intervertebral disks with occlusion of lumbar arteries: a study in adult volunteers

PURPOSE

To evaluate the correlation of the diffusion values in lumbar intervertebral disks with lumbar artery status and the degree of disk degeneration.

MATERIALS AND METHODS

Sagittal T2-weighted images of the lumbar spine were obtained in 37 asymptomatic volunteers aged 22-68 years. The apparent diffusion coefficient (ADC) of 98 lumbar intervertebral disks was determined, and two-dimensional time-of-flight magnetic resonance angiography was performed on the corresponding 98 lumbar artery pairs (total arteries = 196). The degree of disk degeneration and the status of lumbar arteries were evaluated independently by two radiologists. ADC calculations were performed on the basis of the average signal intensities of the selected region of interest in lumbar disks. The association between ADC values of disks, the disk degeneration, and the status of lumbar arteries of the same level were analyzed with analysis of covariance, and pairwise analysis between groups (Scheffé post hoc multiple comparison) was performed with statistical software. P values less than .01 were considered significant.

RESULTS

The lumbar arterial status correlated strongly with the diffusion values of intervertebral disks, and the ADC values decreased with higher degrees of arterial narrowing. The correlation between disk degeneration and diffusion was not significant. Eight severely degenerated disks with normal lumbar artery status and diffusion values were found.

CONCLUSION

Impaired flow in lumbar arteries is significantly associated with decreased diffusion in lumbar disks and may play an important role in disk degeneration.

Periradicular infiltration for sciatica: a randomized controlled trial

STUDY DESIGN

A randomized, double-blind trial was conducted.

OBJECTIVES

To test the efficacy of periradicular corticosteroid injection for sciatica.

SUMMARY OF BACKGROUND DATA

The efficacy of epidural corticosteroids for sciatica is controversial. Periradicular infiltration is a targeted technique, but there are no randomized controlled trials of its efficacy.

METHODS

In this study 160 consecutive, eligible patients with sciatica who had unilateral symptoms of 1 to 6 months duration, and who never underwent surgery were randomized for double-blind injection with methylprednisolone bupivacaine combination or saline. Objective and self-reported outcome parameters and costs were recorded at baseline, at 2 and 4 weeks, at 3 and 6 months, and at 1 year.

RESULTS

Recovery was better in the steroid group at 2 weeks for leg pain (P = 0.02), straight leg raising (P = 0.03), lumbar flexion (P = 0.05), and patient satisfaction (P = 0.03). Back pain was significantly lower in the saline group at 3 and 6 months (P = 0.03 and 0.002, respectively), and leg pain at 6 months (13.5, P = 0.02). Sick leaves and medical costs were similar for both treatments, except for cost of therapy visits and drugs at 4 weeks, which were in favor of the steroid injection (P = 0.05 and 0.005, respectively). By 1 year, 18 patients in the steroid group and 15 in the saline group underwent surgery.

CONCLUSIONS

Improvement during the follow-up period was found in both the methylprednisolone and saline groups. The combination of methylprednisolone and bupivacaine seems to have a short-term effect, but at 3 and 6 months, the steroid group seems to experience a "rebound" phenomenon.

Severity of symptoms and signs in relation to magnetic resonance imaging findings among sciatic patients

STUDY DESIGN

A cross-sectional study in sciatic population.

OBJECTIVES

To evaluate the separate roles of nerve root entrapment-based on magnetic resonance imaging-and other discogenic pain mechanisms on disability and physical signs among symptomatic sciatic patients.

SUMMARY OF BACKGROUND DATA

Data symptoms of sciatica are generally understood to be generated by nerve root compression, but other pain mechanisms of sciatica have been suggested.

METHODS

The authors obtained magnetic resonance scans from 160 patients with unilateral sciatic pain. The patients reported the intensity of their back and leg pain and their back-specific disability. Clinical examination and magnetic resonance imaging (1.5 T) was performed on every patient. The degree of disc displacement, neural enhancement, and nerve root compression was evaluated from magnetic resonance scans. The correlations of symptoms and signs with magnetic resonance imaging findings were calculated.

RESULTS

The degree of disc displacement in magnetic resonance imaging did not correlate with any subjective symptoms, nor did nerve root enhancement or nerve compression. Magnetic resonance imaging classification was associated, however, with straight leg raising restriction. In regression analysis, straight leg raising restriction was best explained with a simple classification of nonherniations versus herniations.

CONCLUSIONS

The results suggest that a discogenic pain mechanism other than the nerve root entrapment generates the subjective symptoms among sciatic patients. The findings of this study thus indicate that magnetic resonance imaging is unable to distinguish sciatic patients in terms of the severity of their symptoms.

The efficacy of a continuous quality improvement (CQI) method in a radiological department. Comparison with non-CQI control material

OBJECTIVE

To study the efficacy of continuous quality improvement (CQI) compared to ordinary management in an on-duty radiology department.

MATERIAL AND METHODS

Because of complaints regarding delivery of on-duty radiological services, an improvement was initiated simultaneously at two hospitals, at the HUCH (Helsinki University Central Hospital) utilising the CQI-method, and at the OUH (Oulu University Hospital) with a traditional management process. For the CQI project, a team was formed to evaluate the process with flow-charts, cause and effect diagrams, Pareto analysis and control charts. Interventions to improve the process were based on the results of these analyses.

RESULTS

The team at the HUCH implemented the following changes: A radiologist was added to the evening shift between 15:00-22:00 and a radiographer was moved from the morning shift to 15:00-22:00. A clear improvement was achieved in the turn-around time, but in the follow-up some of the gains were lost. Only minimal changes were achieved at the OUH, where the intervention was based on traditional management processes.

CONCLUSION

CQI was an effective method for improving the quality of performance of a radiology department compared with ordinary management methods, but some of this improvement may be subsequently lost without a continuous measurement system.

Nerve root infiltration of the first sacral root with MRI guidance

The purpose of this clinical trial was to describe the methodology and evaluate the accuracy of optical tracking-based magnetic resonance (MR)-guided infiltration of the first sacral (S1) root. Thirty-five infiltrations were performed on 34 patients with a 0. 23-T open C-arm magnet installed in a fully equipped operation room with large-screen (36 inches) display and optical navigator utilizing infrared passive tracking. T1 and T2 fast spin-echo (FSE) images were used for localizing the target and fast field echo for monitoring the procedure. Saline as contrast agent in single-shot (SS)FSE images gave sufficient contrast-to-noise ratio. Twenty-four patients had unoperated L5/S1 disc herniation, and 10 had S1 root irritation after failed back surgery. Needle placement was successful in 97% of the cases, and no complications occurred. Outcome was evaluated 1-6 months (mean 2.2 months) after the procedure and was comparable to that of other studies using fluoroscopy or computed tomography guidance. MR-guided placement of the needle is an accurate technique for first sacral root infiltration.

Slow vasomotor fluctuation in fMRI of anesthetized child brain

Signal intensity changes in fMRI during rest caused by vasomotor fluctuations were investigated in this work. Resting-state baseline fluctuations were evaluated in 12 children anesthetized with thiopental. Five subjects had fluctuations related to subvoxel motion. In seven subjects without significant motion, slow signal fluctuation at 0.025-0.041 Hz near one or more primary sensory cortices was observed. In each subject the amplitude and frequency of the fluctuations were stable. It is hypothesized that thiopental, which reduces blood pressure and flow in the cortex, alters the feedback in neurovascular coupling leading to an increase in the magnitude and a reduction in the frequency of these fluctuations. The use of anesthesia in fMRI may provide new insight into neural connectivity and the coupling of blood flow and neural metabolism.

Apparent diffusion coefficient in thoracolumbar intervertebral discs of healthy young volunteers

Apparent diffusion coefficient values (ADC) of healthy intervertebral discs of young volunteers in the thoracolumbar spine were determined using a single-shot EPI sequence. ADC(z) was in the lumbar spine slightly higher than ADC(x) or ADC(y). In vivo diffusion measurements of intervertebral discs may offer a novel diagnostic tool to evaluate disc diseases in early phases.

Initial experience with a wireless personal digital assistant as a teleradiology terminal for reporting emergency computerized tomography scans

A new type of terminal device, a wireless personal digital assistant (PDA) based on a GSM digital cellular phone, was used to transmit computerized tomography scans of 21 patients to a neuroradiologist. All transmitted images were suitable for a preliminary consultation and in one case a final report could be made. In 18 cases the findings were compatible with the reference film reading performed later and in three cases there were minor differences of no clinical importance. Transmission of a single image lasted 1 min 30 s and the transmission of a complete brain scan (14 images) took on average 21 min. The total process of transmission and interpretation of a brain examination series took on average 40 min. In this pilot study the neuroradiologist gained essential information in 24% of the cases and beneficial information in 62%. The neuroradiologist considered that the image consultation saved a hospital visit in 15 cases (71%). Although PDA technology is at an early stage of development and has numerous limitations, it is likely that future technical improvements will allow easier clinical consultations for neurosurgeons and neurologists.

Association of atherosclerosis with low back pain and the degree of disc degeneration

STUDY DESIGN

This was a cross-sectional observational study in which the abdominal aorta was evaluated for atheromatous lesions visible in computed tomographic scans in patients with and without low back pain.

OBJECTIVES

To evaluate whether patients with low back pain have more atherosclerosis in the abdominal aorta than patients without low back pain and whether the severity of atherosclerosis in the abdominal aorta correlates with the grade of disc damage.

SUMMARY OF BACKGROUND DATA

There are studies in which results indicate that insufficient blood supply may be a significant causative factor in disc degeneration. There are also studies in which smoking, one of the risk factors for arterial disease, has been correlated with low back pain. Calf pain has also been shown to correlate with low back pain. Results in a long-term follow-up study have further indicated an association between disc diseases and fatal ischemic heart disease. However, there seems to be only one postmortem study in which results show an association between atherosclerosis in the arteries of the lumbar area and disc diseases.

METHODS

Computed tomographic images of 29 patients with low back pain, who had been evaluated with computed tomographic discography for diagnostic purposes, were evaluated for the quantity of atherosclerotic calcifications visible on computed tomographic scans of the abdominal aorta. A similar evaluation was performed in an age- and sex-matched control group of 52 patients without low back pain selected from among the patients referred for abdominal computed tomography.

RESULTS

Sixteen (55%) of the 29 patients with low back pain had atherosclerotic calcifications visible on computed tomographic scans, whereas 11 (21%) of the 52 age-matched patients without low back pain were found to have aortic calcifications. Eleven (48%) patients with low back pain who were 50 years of age or less (n = 23) had aortic calcifications, whereas only 3 (8%) of the 36 control patients aged less than 50 years had aortic calcifications. There was no correlation between the amount of calcifications and the degree of disc degeneration assessed by computed tomographic discography.

CONCLUSIONS

A significant association is indicated between atheromatous lesions in the abdominal aorta and low back pain.

Digital wireless radiology consultations with a portable computer

A wireless system for radiological subspecialist consultation based on a portable personal computer and a GSM cellular phone was tested. A link with secure access to the hospital image network was built. A total of 68 emergency computerized tomography (CT) examinations were transmitted. Transmission time via GSM for a single CT image was 1 min and for a complete head scan was 18 min. The transmitted images were acceptable for final diagnosis in 72% of the cases, the rest being acceptable for preliminary diagnosis. The diagnosis from the transmitted images did not change after a later review of the original images in 97% of cases. The wireless link saved a hospital visit by the senior radiologist in 24% of cases. The results show that a remote consultation link can be built with readily available technology and that the technique is useful in radiological subspecialist consultations for CT images.

An allele of COL9A2 associated with intervertebral disc disease

Intervertebral disc disease is one of the most common musculoskeletal disorders. A number of environmental and anthropometric risk factors may contribute to it, and recent reports have suggested the importance of genetic factors as well. The COL9A2 gene, which codes for one of the polypeptide chains of collagen IX that is expressed in the intervertebral disc, was screened for sequence variations in individuals with intervertebral disc disease. The analysis identified a putative disease-causing sequence variation that converted a codon for glutamine to one for tryptophan in six out of the 157 individuals but in none of 174 controls. The tryptophan allele cosegregated with the disease phenotype in the four families studied, giving a lod score (logarithm of odds ratio) for linkage of 4.5, and subsequent linkage disequilibrium analysis conditional on linkage gave an additional lod score of 7.1.

MR imaging in tibial shaft fractures. A potential method for early visualization of delayed union

PURPOSE

To evaluate the relationship between MR findings at the fracture site during the healing process and the outcome of patients with tibial shaft fracture.

MATERIAL AND METHODS

Twelve consecutive patients with an uncomplicated tibial fracture treated conservatively were imaged by MR 1 to 3 days, 1 week, 3 weeks, 6 weeks and 12 weeks after the trauma. MR imaging consisted of sagittal/coronal T1-weighted, T2-weighted, proton density, short-tau inversion recovery, and contrast-enhanced T1-weighted spin-echo images. The images were analysed for the extent of signal pathology in the bone marrow adjacent to the fracture, the extent of soft tissue oedema, and the intensity and homogeneity of the contrast enhancement of the callus.

RESULTS

The differences between normal (n=7) and delayed union (n=5) were observed within 3 to 6 weeks after the trauma, mainly in the homogeneity of the callus in T2-weighted and contrast-enhanced images.

CONCLUSION

MR imaging is a potentially valuable method for early visualization of delayed union in tibial shaft fractures.