Pediatric Musculoskeletal Interventional MRI.

Minimally invasive procedures play a crucial role in the diagnosis and treatment of many pediatric musculoskeletal conditions. Although computed tomography and fluoroscopy are commonly used for image guidance, the associated exposure to ionizing radiation is especially concerning in pediatric patients. Ultrasonography may be used successfully in a subset of interventions, but it is often not useful for complex, deep, and osseous targets. Interventional magnetic resonance imaging (iMRI) facilitates targeting and treatment of musculoskeletal lesions at many locations with high accuracy due to its excellent tissue contrast. Furthermore, MRI provides imaging guidance without the use of ionizing radiation and as such complies with the ALARA practice mandate in a formidable fashion. MRI guidance is our method of choice for lesion that are not visible by other modalities or when other techniques and modalities failed. MRI guidance is especially useful for selective targeting of complex lesions, intra-articular lesions, cyst aspirations in difficult locations of the body, and lesions that are located adjacent to surgical hardware. Tumor-related diagnostic sampling is more frequently performed under MRI; however, MRI guidance is also exquisitely well suited for a variety of therapeutic percutaneous osseous or articular conditions, such as osteoid osteoma, epiphyseal bone bridging, osteochondritis dissecans lesions, and aneurysmal bone cysts. In this article, we will describe the technical aspects and clinical indications of a variety of MRI-guided pediatric procedures in the musculoskeletal system.

Quantitative MRI of Human Cartilage In Vivo: Relationships with Arthroscopic Indentation Stiffness and Defect Severity.

Objective To investigate the association of cartilage defect severity, as determined by the International Cartilage Repair Society (ICRS) grading with indentation stiffness and T2 relaxation time of magnetic resonance imaging (MRI), a biomarker for the integrity of articular cartilage. Design Twenty-one patients scheduled for arthroscopic were included in the study. Prior to arthroscopy, subjects underwent quantitative MRI of articular cartilage, namely T2 relaxation time mapping at 1.5 T. Within 2 months, subjects underwent arthroscopy, which also included ICRS grading and measurement of arthroscopic indentation stiffness. Arthroscopic evaluations and T2 mapping at anterior, central, and posterior medial and lateral femoral condyles were correlated using a colocalization scheme. Differences in Young's modulus, as derived by indentation tests, and T2 times between ICRS grades were analyzed using Mann-Whitney's U or Kruskal-Wallis H tests. The correlation between modulus and T2 times was analyzed using Spearman's rank correlation coefficients. Results Modulus and T2 showed significant topographical variation. In the anterior region of interest (ROI) on the medial condyle the modulus showed a negative association with ICRS grade ( P = 0.040) and the T2 times were longer in ICRS grade 2 compared with grades 0 and 1 ( P = 0.047). Similar, but nonsignificant associations were found in the central ROI on the medial condyle. No significant correlations were observed between the indentation modulus and T2 times. Conclusions Cartilage degeneration is identified both with mechanical indentation and T2 mapping in MRI. However, in this study, indentation stiffness and T2 relaxation time in vivo, were not associated.

Effect of First Tarsometatarsal Joint Derotational Arthrodesis on First Ray Dynamic Stability Compared to Distal Chevron Osteotomy.

BACKGROUND: Hallux valgus alters gait, compromising first ray stability and function of the windlass mechanism at the late stance. Hallux valgus correction should restore the stability of the first metatarsal. Comparative studies reporting the impact of different hallux valgus correction methods on gait are rare. We report the results of a case-control study between distal chevron osteotomy and first tarsometatarsal joint derotational arthrodesis (FTJDA). METHODS: Two previously studied hallux valgus cohorts were matched: distal chevron osteotomy and FTJDA. Seventy-seven feet that underwent distal chevron osteotomy (chevron group) and 76 feet that underwent FTJDA (FTJDA group) were available for follow-up, with a mean of 7.9 years (range, 5.8-9.4 years) and 5.1 years (range, 3.0-8.3 years), respectively. Matching criteria were the hallux valgus angle (HVA) and a follow-up time difference of a maximum 24 months. Two matches were made: according to the preoperative HVA and the HVA at late follow-up. Matching provided 30 and 31 pairs, respectively. Relative impulses (%) of the first toe (T1) and metatarsal heads 1 to 5 (MTH1-5), weightbearing radiographs, and American Orthopaedic Foot & Ankle Society (AOFAS) (hallux metatarsophalangeal-interphalangeal [MTP-IP]) scores were studied. RESULTS: The relative impulse of MTH1 was higher in the FTJDA group, whereas a central dynamic loading pattern was seen in the chevron group. This result remained when relative impulses were analyzed according to the postoperative HVA. The mean difference in the HVA at follow-up was 6.2 degrees (95% confidence interval, 3.0-9.5; P = .001) in favor of the FTJDA group. CONCLUSION: The dynamic loading capacity of MTH1 was higher in the FTJDA group in comparison to the chevron group. The follow-up HVA remained better in the FTJDA group. LEVEL OF EVIDENCE: Level III, case-control study.

Association between quantitative MRI and ICRS arthroscopic grading of articular cartilage.

PURPOSE: To investigate the association of quantitative magnetic resonance imaging (qMRI) parameters with arthroscopic grading of cartilage degeneration. Arthroscopy of the knee is considered to be the gold standard of osteoarthritis diagnostics; however, it is operator-dependent and limited to the evaluation of the articular surface. qMRI provides information on the quality of articular cartilage and its changes even at early stages of a disease. METHODS: qMRI techniques included T 1 relaxation time, T 2 relaxation time, and delayed gadolinium-enhanced MRI of cartilage mapping at 3 T in ten patients. Due to a lack of generally accepted semiquantitative scoring systems for evaluating severity of cartilage degeneration during arthroscopy, the International Cartilage Repair Society (ICRS) classification system was used to grade the severity of cartilage lesions. qMRI parameters were statistically compared to arthroscopic grading conducted with the ICRS classification system. RESULTS: qMRI parameters were not linearly related to arthroscopic grading. Spearman's correlation coefficients between qMRI and arthroscopic grading were not significant. The relative differences in qMRI parameters of superficial and deep cartilage varied with degeneration, suggesting different macromolecular alterations in different cartilage zones. CONCLUSIONS: Results suggest that loss of cartilage and the quality of remaining tissue in the lesion site may not be directly associated with each other. The severity of cartilage degeneration may not be revealed solely by diagnostic arthroscopy, and thus, qMRI can have a role in the investigation of cartilage degeneration.

MRI-guidance in percutaneous core decompression of osteonecrosis of the femoral head.

OBJECTIVES: The purpose of this study was to evaluate the usefulness of MRI-guidance for core decompression of avascular necrosis of the femoral head. MATERIALS AND METHODS: Twelve MRI-guided core decompressions were performed on patients with different stages of avascular necrosis of the femoral head. The patients were asked to evaluate their pain and their ability to function before and after the procedure and imaging findings were reviewed respectively. RESULTS: Technical success in reaching the target was 100 % without complications. Mean duration of the procedure itself was 54 min. All patients with ARCO stage 1 osteonecrosis experienced clinical benefit and pathological MRI findings were seen to diminish. Patients with more advanced disease gained less, if any, benefit and total hip arthroplasty was eventually performed on four patients. CONCLUSIONS: MRI-guidance seems technically feasible, accurate and safe for core decompression of avascular necrosis of the femoral head. Patients with early stage osteonecrosis may benefit from the procedure. KEY POINTS: • MRI is a useful guidance method for minimally invasive musculoskeletal interventions. • Bone drilling seems beneficial at early stages of avascular necrosis. • MRI-guidance is safe and accurate for bone drilling.

Preoperative radiological factors correlated to long-term recurrence of hallux valgus following distal chevron osteotomy.

BACKGROUND: The purpose of this article was to analyze the long-term radiologic results after distal chevron osteotomy for hallux valgus treatment and to determine the preoperative radiographic factors correlating with radiological recurrence of the deformity. METHODS: The study included 100 consecutive patients who received distal chevron osteotomy for hallux valgus. The osteotomy included fixation with an absorbable pin in 50 cases, and no fixation in the other 50. For 6 weeks postoperatively, half of each group used a soft cast and half had a traditional elastic bandage. Weight-bearing radiographs were evaluated at 6 weeks, 6 months, 1 year, and a mean of 7.9 (range, 5.8-9.4) years postoperatively. RESULTS: At the final follow-up, radiological recurrence of hallux valgus deformity (HVA > 15 degrees) was observed in 56 feet (73%). Eleven feet (14%) had mild recurrence (HVA < 20 degrees), 44 (57%) moderate (20 degrees ≥ HVA < 40 degrees), and 1 (1%) severe (HVA ≥ 40 degrees). All recurrences were painless, and thus no revision surgery was required. Long-term hallux valgus recurrence was significantly affected by preoperative congruence, DMAA, sesamoid position, HVA, and I/II IMA. CONCLUSIONS: Radiological recurrence of hallux valgus deformity of 15 degrees or more was very common at long-term follow-up after distal chevron osteotomy. Preoperative congruence, DMAA, sesamoid position (LaPorta), HVA, and I/II IMA significantly affected recurrence. LEVEL OF EVIDENCE: Level III, comparative case series.

MRI-guided percutaneous retrograde drilling of osteochondritis dissecans of the talus: a feasibility study.

OBJECTIVES: The purpose of this study was to evaluate the feasibility of MRI guidance for percutaneous retrograde drilling in the treatment of osteochondritis dissecans of the talus (OCDT). METHODS: Four patients, one juvenile and three adults, with one OCDT lesion each and persisting ankle pain after conservative treatment, were treated with MRI-guided retrograde drilling. All lesions were stable and located in the middle or posterior medial third of the talar dome. Pain relief and the ability to return to normal activities were assessed during clinical follow-up. MRI and plain film radiographs were used for imaging follow-up. RESULTS: Technical success was 100% with no complications and with no damage to the overlying cartilage. All patients experienced some clinical benefit, although only one had complete resolution of pain and one had a relapse leading to surgical treatment. Changes in the pathological imaging findings were mostly very slight during the follow-up period. CONCLUSIONS: MRI guidance seems accurate, safe and technically feasible for retrograde drilling of OCDT. Larger series are needed to reliably assess its clinical value. KEY POINTS: • MRI serves as a useful guidance method for numerous mini-invasive applications. • Retrograde drilling is a cartilage-sparing alternative in the treatment of osteochondritis dissecans. • MRI guidance seems feasible for treatment of osteochondritis dissecans of the talus.

First tarsometatarsal joint derotational arthrodesis--a new operative technique for flexible hallux valgus without touching the first metatarsophalangeal joint.

No operative technique for hallux valgus has been introduced in which the first metatarsophalangeal joint is not touched. We report the first tarsometatarsal joint derotational arthrodesis in which we mimic the function of the peroneus longus tendon without involving the first metatarsophalangeal joint, allowing function of the windlass mechanism without interference. We treated 66 patients (62 women and 4 men) with 84 flexible hallux valgus feet using our new operative technique. Preoperative and postoperative follow-up weightbearing radiographs were evaluated. Most patients had a pronation type foot (78%) preoperatively, and mean correction in hallux valgus and intermetatarsal angle was 20° and 9°, respectively (p < .001). The LaPorta classification showed a median change of 2.5 U (p < .001). We have described a new operative technique for flexible hallux valgus. The first tarsometatarsal joint derotational arthrodesis showed notable correction angles in hallux valgus, although the first metatarsophalangeal joint was left intact.

Effects of high-impact training on bone and articular cartilage: 12-month randomized controlled quantitative MRI study.

Osteoarthritis and osteoporosis often coexist in postmenopausal women. The simultaneous effect of bone-favorable high-impact training on these diseases is not well understood and is a topic of controversy. We evaluated the effects of high-impact exercise on bone mineral content (BMC) and the estimated biochemical composition of knee cartilage in postmenopausal women with mild knee osteoarthritis. Eighty women aged 50 to 66 years with mild knee osteoarthritis were randomly assigned to undergo supervised progressive exercise three times a week for 12 months (n = 40) or to a nonintervention control group (n = 40). BMC of the femoral neck, trochanter, and lumbar spine was measured by dual-energy X-ray absorptiometry (DXA). The biochemical composition of cartilage was estimated using delayed gadolinium-enhanced magnetic resonance imaging (MRI) cartilage (dGEMRIC), sensitive to cartilage glycosaminoglycan content, and transverse relaxation time (T2) mapping that is sensitive to the properties of the collagen network. In addition, we evaluated clinically important symptoms and physical performance-related risk factors of falling: cardiorespiratory fitness, dynamic balance, maximal isometric knee extension and flexion forces, and leg power. Thirty-six trainees and 40 controls completed the study. The mean gain in femoral neck BMC in the exercise group was 0.6% (95% CI, -0.2% to 1.4%) and the mean loss in the control group was -1.2% (95% CI, -2.1% to -0.4%). The change in baseline, body mass, and adjusted body mass change in BMC between the groups was significant (p = 0.005), whereas no changes occurred in the biochemical composition of the cartilage, as investigated by MRI. Balance, muscle force, and cardiorespiratory fitness improved significantly more (3% to 11%) in the exercise group than in the control group. Progressively implemented high-impact training, which increased bone mass, did not affect the biochemical composition of cartilage and may be feasible in the prevention of osteoporosis and physical performance-related risk factors of falling in postmenopausal women.

MRI-guided biopsy and fine needle aspiration biopsy (FNAB) in the diagnosis of musculoskeletal lesions.

OBJECTIVES: The purpose of this study was to evaluate the diagnostic performance of magnetic resonance imaging (MRI) guided musculoskeletal biopsy and the value of fine needle aspiration biopsy (FNAB) when combined with histologic biopsy. MATERIALS AND METHODS: A total of 172 biopsies were performed under MRI guidance, 170 were histologic biopsies. In 112 cases, a fine needle aspiration biopsy was also performed. In two cases, a stand-alone FNAB was performed. The diagnostic performance was evaluated retrospectively by comparing the histopathologic and cytologic diagnosis with the current or final diagnosis after at least one year of clinical and imaging follow-up. A 0.23 T open MRI scanner with an interventional stereotactic guidance system was used. RESULTS: The overall diagnostic accuracy of MRI guided biopsy was 0.95, sensitivity 0.91, specificity 0.98, positive predictive value (ppv) 0.97 and negative predictive value (npv) 0.93. The diagnostic accuracy of trephine biopsy alone was 0.93, sensitivity 0.89, specificity 0.98, ppv 0.97 and npv 0.91 and accuracy for FNAB alone was 0.85, sensitivity 0.80, specificity 0.90, ppv 0.89 and npv 0.82. CONCLUSIONS: MRI guidance is a feasible and accurate tool in percutaneous musculoskeletal biopsies. Fine needle biopsy is a useful low-cost supplement to histologic biopsy.

MR-guided neurolytic celiac plexus ablation: an evaluation of effect and injection spread pattern in cancer patients with celiac tumor infiltration.

OBJECTIVE: The purpose of this study was to evaluate the feasibility, the initial accuracy, and the effects of the MR-guided neurolytic celiac plexus ablation as a method to treat cancer-induced chronic abdominal pain. METHODS: Thirteen celiac plexus ablations were performed for 12 patients. A 0.23-T open MRI scanner with optical navigation was used for procedural guidance. As an adjunct to the MR-guided needle positioning, the needle location was confirmed with saline injection and consequent MR imaging (STIR sequence). The spread of the ablative injection material (alcohol-lidocaine mix) was observed by repeating this sequence after the therapeutic injection. Pain scores from seven patients (eight ablations) were used to assess the therapy effect. RESULTS: MR guidance allowed adequate needle positioning and visualization of injection material in all cases. The rest pain scores significantly decreased from 4 (median) at baseline to 1 (median) at 2 weeks (p < 0.05). Average and worst pain experienced during the past week were significantly lower at the 2-week time point compared with the baseline (p < 0.05). However, the intervention did not result in reduction of opioid use at 2 weeks. CONCLUSIONS: MR guidance is an accurate and safe method for celiac plexus ablation with positive therapeutic effect.

Radiographic analysis of the impact of internal fixation and dressing choice of distal chevron osteotomy: randomized control trial.

BACKGROUND: The aim of this study was to perform prospective, randomized comparison of two surgical techniques (fixation versus no fixation) and two postoperative regimens (soft cast versus elastic band) to determine if the head fragment displaces more or less with either technique. METHODS: One hundred consecutive patients were included in the study. The osteotomy was fixed with an absorbable pin in 50 cases and no fixation in the other 50. Half of each group used a soft cast for 6 weeks postoperatively and half had a traditional elastic bandage. Weightbearing radiographs at 6 weeks, 6 months, 1 year, and mean of 7.9 years were evaluated. RESULTS: A larger shift was found when fixation was used 3.9 (SD, 0.8) mm at 6 weeks versus 3.1 (SD, 0.9) mm in the no fixation group (p < 0.001). The two bandage types had no significant effect to the mean shift. Correction of the mean hallux valgus angle was worse overall when preoperative angles were over 30 degrees (p < 0.001). CONCLUSION: There was a statistically higher shift in the fixation group, but the clinical significance of 0.7 mm difference and the type of postoperative bandaging did not influence outcome is questionable. The risk for recurrence of hallux valgus was higher when preoperative angles were over 30 degrees.

MRI-guided percutaneous retrograde drilling of osteochondritis dissecans of the knee.

OBJECTIVE: The purpose of this study was to evaluate the feasibility of a new method for osteochondritis dissecans (OCD) treatment. MATERIALS AND METHODS: Ten OCD lesions of the knee unresponsive to conservative management were treated with MRI-guided percutaneous retrograde drilling to reduce symptoms and promote ossification of the lesion. All lesions were located in distal femoral condyles. Only stable OCD lesions were included (preprocedural MRI grade I or II). Five lesions were of juvenile type and five lesions were of adult type OCD. All the patients had severe limitation of activity due to the OCD-related pain. By using a 0.23 T open MRI scanner and spinal anesthesia, percutaneous retrograde drilling of the OCD lesions was performed (3 mm cylindrical drill, one to three channels). Optical tracking and MRI imaging were used to guide instruments during the procedure. Mean postprocedural clinical follow-up time was 3 years. Eight patients had a post-procedural follow-up MRI within 1 year. RESULTS: All the OCD lesions were located and drilled using the 0.23 T open MRI scanner without procedural complications. All the patients had pain relief, mean visual analog score (VAS) declined from 6 to 2. Follow-up MRI showed ossification in all lesions. Eight patients could return to normal physical activity with no or minor effect on function (Hughston score 3-4). Treatment failed in two cases where the continuation of symptoms led to arthroscopy and transchondral fixation. CONCLUSION: [corrected] MR-guided retrograde OCD lesion drilling is an accurate, feasible, and effective cartilage-sparing techique in OCD management.

Percutaneous magnetic resonance imaging-guided bone tumor management and magnetic resonance imaging-guided bone therapy.

Magnetic resonance imaging (MRI) is promising tool for image-guided therapy. In musculoskeletal setting, image-guided therapy is used to direct diagnostic and therapeutic procedures and to steer patient management. Studies have demonstrated that MRI-guided interventions involving bone, soft tissue, joints, and intervertebral disks are safe and in selected indications can be the preferred action to manage clinical situation. Often, these procedures are technically similar to those performed in other modalities (computed tomography, fluoroscopy) for bone and soft tissue lesions. However, the procedural perception to the operator can be very different to other modalities because of the vastly increased data.Magnetic resonance imaging guidance is particularly advantageous should the lesion not be visible by other modalities, for selective lesion targeting, intra-articular locations, cyst aspiration, and locations adjacent to surgical hardware. Palliative tumor-related pain management such as ablation therapy forms a subset of procedures that are frequently performed under MRI. Another suitable entity for MRI guidance are the therapeutic percutaneous osseous or joint-related benign or reactive conditions such as osteoid osteoma, epiphyseal bone bridging, osteochondritis dissecans, bone cysts, localized bone necrosis, and posttraumatic lesions. In this article, we will describe in detail the technical aspects of performing MRI-guided therapeutic musculoskeletal procedures as well as the clinical indications.

Liver tumor laser ablation - increase in the subacute ablation lesion volume detected with post procedural MRI.

BACKGROUND: The use of image-guided thermoablative methods in liver tumor treatment has expanded rapidly due to encouraging results and advanced imaging. However, little is known about the treatment-induced tissue response and effects on imaging findings during the subacute post procedural period. PURPOSE: To study the development of subacute ablation zone volume with magnetic resonance imaging (MRI) after laser-mediated liver tumor thermal therapy. MATERIAL AND METHODS: In all, 16 laser ablations were performed on 16 liver tumors resulting in 16 ablation zones in 11 consecutive patients. A low-field 0.23 T C-arm MRI scanner was used for imaging and procedural guidance. Repeated dynamic contrast-enhanced T1, contrast-enhanced T1 FSE, and T2 FSE studies of liver were performed at 0 and 72 h after the procedure. Ablation zone volumes were registered from the acquired image data. RESULTS: MRI scans showed a significant increase of ablation volume in all imaging sequences obtained at 72 h after the initial therapy. CONCLUSION: After laser ablation, there is a progressive perfusion decrease in the ablation site leading to an increase in the ablation volume. Post procedural baseline MRI at 72 h from the treatment provides more precise information about the ablation result than can be obtained with immediate post procedural MRI.

The standing fixed flexion view detects narrowing of the joint space better than the standing extended view in patients with moderate osteoarthritis of the knee.

BACKGROUND AND PURPOSE: It is unclear whether osteoarthritis (OA) of the knee is seen better in standing flexion position radiographs than in the standing extended view. We assessed the value of standing flexion views. PATIENTS AND METHODS: We retrospectively evaluated 1,090 radiographs of 545 consecutive knees with non-traumatic knee pain, comparing standing fixed flexion view (FFV) and standing extended view (SEV). OA was classified according to the Kellgren-Lawrence (KL) radiographic grading scale and joint space widths were measured. RESULTS: Medial joint space width was lower on average in the FFV, with the greatest difference in KL II knees. Medial full-thickness loss of cartilage was also seen more often in the FFVs of knees with moderate OA (KL II-III) than in the SEVs (6% vs. 19%). INTERPRETATION: Using FFV, there is no need to measure the exact knee flexion angle to use fluoroscopy. In earlier studies, the FFV has been found to be reproducible and easy to use in clinical practice. We recommend using flexion views when deciding the appropriate type of intervention in patients with OA. Full-thickness loss of cartilage in particular is better seen in the flexion view, which may be helpful if planning unicompartmental knee arthroplasty.

MRI-guided percutaneous laser ablation of small renal cell carcinoma: Initial clinical experience.

BACKGROUND: The number of detected small renal cell carcinomas (RCCs) has been rising, largely due to advances in imaging. Open surgical resection is the standard management of small RCCs; however, imaging-guided percutaneous ablative therapies have emerged as a minimally invasive treatment alternative, especially for patients who are poor candidates for surgery. PURPOSE: To evaluate the initial clinical experience of magnetic resonance imaging (MRI)-guided percutaneous laser ablation of small RCCs. MATERIAL AND METHODS: Eight patients with 10 tumors were treated with percutaneous MRI-guided laser ablation. All tumors (diameter range 1.5-3.8 cm, mean 2.7 cm) were biopsy-proven RCCs. By using a 0.23 T open MRI system and general anesthesia in patients, one to four (mean 2.6) laser fibers were placed and the tumors were ablated under near real-time MRI control by observing the signal void caused by the temperature change in the heated tissue. The treatment was considered successful if the tumor showed no contrast enhancement at follow-up imaging. RESULTS: All except one tumor were successfully ablated in one session. The first patient treated showed enhancing residual tumor in post-procedural MRI; she has thus far declined retreatment. One complication, a myocardial infarction, occurred; all other patients tolerated the procedure well. No local recurrence was discovered during the follow-up (range 12-30 months, mean 20 months). CONCLUSION: In this small group of patients with relatively short follow-up period, MRI-guided percutaneous laser ablation proved to be a promising treatment option for small RCCs.

Association of lumbar artery narrowing, degenerative changes in disc and endplate and apparent diffusion in disc on postcontrast enhancement of lumbar intervertebral disc.

OBJECTIVE: A decreased supply of nutrition to the intervertebral disc can lead to disc degeneration. Nutrient supply can be simulated in vivo by measuring gadolinium enhancement of the disc. We aimed to study the changes associated with disc degeneration that may have effect on the nutrition of the disc, i.e. lumbar artery narrowing, Modic changes, endplate defects, and apparent diffusion coefficient (ADC) in nucleus pulposus. PATIENTS AND METHODS: Twenty male volunteers underwent a lumbar spine examination at 1.5 T for anatomical imaging, diffusion weighted imaging, magnetic resonance angiography, and for T1 relaxation time quantification of contrast enhancement of intervertebral disc. RESULTS: Enhancement of the disc increased with degeneration. Disc space narrowing associated strongly with the enhancement (Pearson's correlation coefficient 0.46, P < 0.001). The enhancement rate in discs adjacent to Modic type 2 changes was 24%, adjacent to type 1/2 changes 58%, and 13% in the absence of Modic changes. Discs adjacent to endplate defects enhanced 32% compared to 10% of normal endplates. Lumbar artery narrowing or ADC in the disc were not associated with the enhancement. CONCLUSION: Increased enhancement of a degenerated disc is associated mostly with disc space narrowing and with the presence of degenerative endplate changes and endplate defects.

MRI-guided percutaneous nephrostomy: a feasibility study.

The purpose of this study was to assess the feasibility and safety of magnetic resonance imaging (MRI)-guided PCN in an open-configuration low-field MRI system. Eight patients were prospectively enrolled in the study. The degree of the dilatation of the renal collecting system varied from minimal to severe. All procedures were performed solely under MRI guidance with a 0.23-T open configuration C-arm-shaped MRI system with interventional optical tracking. In each case, PCN was performed with a MRI-compatible drainage kit using the Seldinger technique. Seven out of eight nephrostomies were successfully performed under MRI guidance. All PCN procedures in dilated renal collection systems were successful; however, nephrostomy catheter could not be placed in a nondilated system. The mean time needed for the MRI-guided PCN was 26 min. No major complications occurred during the procedure or follow-up. MRI-guided PCN in dilated renal collection system is feasible and safe. The presented technique has limitations that necessitate further technical developments before the procedure can be applied to nondilated kidneys and recommended for routine clinical use.

Are the determinants of vertebral endplate changes and severe disc degeneration in the lumbar spine the same? A magnetic resonance imaging study in middle-aged male workers.

BACKGROUND: Modic changes are bone marrow lesions visible in magnetic resonance imaging (MRI), and they are assumed to be associated with symptomatic intervertebral disc disease, especially changes located at L5-S1. Only limited information exists about the determinants of Modic changes. The objective of this study was to evaluate the determinants of vertebral endplate (Modic) changes, and whether they are similar for Modic changes and severe disc degeneration focusing on L5-S1 level. METHODS: 228 middle-aged male workers (159 train engineers and 69 sedentary factory workers) from northern Finland underwent sagittal T1- and T2-weighted MRI. Modic changes and disc degeneration were analyzed from the scans. The participants responded to a questionnaire including items of occupational history and lifestyle factors. Logistic regression analysis was used to evaluate the associations between selected determinants (age, lifetime exercise, weight-related factors, fat percentage, smoking, alcohol use, lifetime whole-body vibration) and Modic type I and II changes, and severe disc degeneration (= grade V on Pfirrmann's classification). RESULTS: The prevalences of the Modic changes and severe disc degeneration were similar in the occupational groups. Age was significantly associated with all degenerative changes. In the age-adjusted analyses, only weight-related determinants (BMI, waist circumference) were associated with type II changes. Exposure to whole-body vibration, besides age, was the only significant determinant for severe disc degeneration. In the multivariate model, BMI was associated with type II changes at L5-S1 (OR 2.75 per one SD = 3 unit increment in BMI), and vibration exposure with severe disc degeneration at L5-S1 (OR 1.08 per one SD = 11-year increment in vibration exposure). CONCLUSION: Besides age, weight-related factors seem important in the pathogenesis of Modic changes, whereas whole-body vibration was the only significant determinant of severe disc degeneration.