Naveen S. Murthy

Identification of Intraarticular and Periarticular Uric Acid Crystals with Dual-Energy CT: Initial Evaluation

PURPOSE To estimate the accuracy, sensitivity, specificity, and interobserver agreement of dual-energy computed tomography (CT) in detection of uric acid crystals in joints or periarticular structures in patients with arthralgia and patients suspected of having gout, with joint aspiration results as reference standard. MATERIALS AND METHODS With institutional review board approval, patient consent, and HIPAA compliance, 94 patients (age range, 29-89 years) underwent dual-source, dual-energy (80 and 140 kVp) CT of a painful joint. A material decomposition algorithm was used to identify uric acid. Two blinded musculoskeletal radiologists evaluated the dual-energy CT images and classified the examination findings as positive or negative for the presence of uric acid crystals. Reference standard was the result of joint aspiration. RESULTS Forty-three of 94 patients (46%) underwent attempted joint aspiration within 1 month of dual-energy CT. Aspiration was successful in 31 of 43 patients (72%). In 12 of 31 patients (39%), uric acid crystals were identified at joint aspiration; in 19 patients, they were not. Readers 1 and 2 had no false-negative findings for uric acid at dual-energy CT. Sensitivity was 100% (12 of 12; 95% confidence interval (CI): 74%, 100%) for both readers. Specificity was 89% (17 of 19; 95% CI: 67%, 99% ) for reader 1 and 79% (15 of 19; 95% CI: 54%, 94%) for reader 2, with near-perfect agreement between the readers (κ = 0.87; range, 0.70-1.00) in the 31 patients who underwent aspiration. CONCLUSION Initial retrospective assessment suggests that dual-energy CT is a sensitive, noninvasive, and reproducible method for identifying uric acid deposits in joints and periarticular soft tissues in patients suspected of having gout.

Dual-energy CT for the diagnosis of gout: an accuracy and diagnostic yield study

Objectives To assess the accuracy of dual-energy CT (DECT) for diagnosing gout, and to explore whether it can have any impact on clinical decision making beyond the established diagnostic approach using polarising microscopy of synovial fluid (diagnostic yield). Methods Diagnostic single-centre study of 40 patients with active gout, and 41 individuals with other types of joint disease. Sensitivity and specificity of DECT for diagnosing gout was calculated against a combined reference standard (polarising and electron microscopy of synovial fluid). To explore the diagnostic yield of DECT scanning, a third cohort was assembled consisting of patients with inflammatory arthritis and risk factors for gout who had negative synovial fluid polarising microscopy results. Among these patients, the proportion of subjects with DECT findings indicating a diagnosis of gout was assessed. Results The sensitivity and specificity of DECT for diagnosing gout was 0.90 (95% CI 0.76 to 0.97) and 0.83 (95% CI 0.68 to 0.93), respectively. All false negative patients were observed among patients with acute, recent-onset gout. All false positive patients had advanced knee osteoarthritis. DECT in the diagnostic yield cohort revealed evidence of uric acid deposition in 14 out of 30 patients (46.7%). Conclusions DECT provides good diagnostic accuracy for detection of monosodium urate (MSU) deposits in patients with gout. However, sensitivity is lower in patients with recent-onset disease. DECT has a significant impact on clinical decision making when gout is suspected, but polarising microscopy of synovial fluid fails to demonstrate the presence of MSU crystals.

Intraforaminal Location of the Great Anterior Radiculomedullary Artery (Artery of Adamkiewicz): A Retrospective Review

PURPOSE The purpose of this study was to better characterize the intraforaminal location of the great anterior radiculomedullary artery (artery of Adamkiewicz [AKA]) within the neural foramen that would allow safer targeting of thoracic and lumbar transforaminal epidural steroid injections. MATERIAL AND METHODS A retrospective review of conventional thoracic and lumbar spinal angiograms performed at the Mayo Clinic from 1998-2008 was conducted. Two hundred forty-eight patients were identified and their spinal angiograms reviewed. The cephalo-caudal location of the AKA within the foramen at the mid-pedicular plane was documented along with the side and level of the AKA. RESULTS From the 248 patients, 113 radiculomedullary arteries could be clearly evaluated within a neural foramen. The AKA was located in the superior one-half of the foramen in 97% (110). Eighty-eight percent (100) were located in the upper third; 9% (10) were located in the middle third; and 2% (2) were located in the lower third. The AKA was never seen in the inferior one-fifth of the foramen. Eighty-eight percent (100) of the radiculomedullary arteries were located on the left while 17% (20) were located on the right. The radiculomedullary arteries were identified from T2-L3. 92% (110) were located between T8 and L1. 28% (34) were located at T10, the highest incidence. CONCLUSIONS The AKA was overwhelmingly located in the superior aspect of the neural foramen. Contrary to traditional teaching, the safest needle placement for an epidural steroid injection, particularly at L3 and above, may not be in the superior aspect of the foramen, but rather in an inferior and slightly posterior position within the foramen and relative to the nerve.

The Noninferiority of the Nonparticulate Steroid Dexamethasone vs the Particulate Steroids Betamethasone and Triamcinolone in Lumbar Transforaminal Epidural Steroid Injections

OBJECTIVE To assess whether a nonparticulate steroid (dexamethasone, 10 mg) is less clinically effective than the particulate steroids (triamcinolone, 80 mg; betamethasone, 12 mg) in lumbar transforaminal epidural steroid injections (TFESIs) in subjects with radicular pain with or without radiculopathy. DESIGN Retrospective observational study with noninferiority analysis of dexamethasone relative to particulate steroids. SETTING Single academic radiology pain management practice. SUBJECTS Three thousand six hundred forty-five lumbar TFESIs at the L4-5, L5-S1, or S1 neural foramina, performed on 2,634 subjects. METHODS/OUTCOME MEASURES Subjects were assessed with a pain numerical rating scale (NRS, 0-10) and Roland-Morris disability questionnaire (R-M) prior to TFESI, and at 2 weeks and 2 months follow-up. For categorical outcomes, successful pain relief was defined as either ≥50% reduction in NRS or pain 0/10; functional success was defined as ≥40% reduction in R-M score. Noninferiority analysis was performed with δ = -10% as the limit of noninferiority. Continuous outcomes (mean NRS, R-M scores) were analyzed for noninferiority with difference bounds of 0.3 for NRS scores and 1.0 for R-M scores. RESULTS With categorical outcomes, dexamethasone was demonstrated to be noninferior to the particulate steroids in pain relief and functional improvement at 2 months. Using continuous outcomes, dexamethasone was demonstrated to be superior to the particulate steroids in both pain relief and functional improvement at 2 months. CONCLUSION This retrospective observational study reveals no evidence that dexamethasone is less effective than particulate steroids in lumbar TFESIs performed for radicular pain with or without radiculopathy.

Validation of a CT-Derived Method for Osteoporosis Screening in IBD Patients Undergoing Contrast-Enhanced CT Enterography

OBJECTIVES:Osteoporosis and bone fractures are of particular concern in patients with inflammatory bowel disease (IBD). Biomechanical computed tomography (BCT) is an image-analysis technique that can measure bone strength and dual-energy X-ray absorptiometry (DXA)-equivalent bone mineral density (BMD) from noncontrast CT images. This study seeks to determine whether this advanced technology can be applied to patients with IBD undergoing CT enterography (CTE) with IV contrast.METHODS:Patients with IBD who underwent a CTE and DXA scan between 2007 and 2011 were retrospectively identified. Femoral neck BMD (g/cm2) and T-scores were measured and compared between DXA and BCT analysis of the CTE images. Femoral strength (Newtons) was also determined from BCT analysis.RESULTS:DXA- and CTE-generated BMD T-score values were highly correlated (R2=0.84, P<0.0001) in this patient cohort (n=136). CTE identified patients with both osteoporosis (sensitivity, 85.7%; 95% confidence interval (CI), 48.7–97.4 and specificity, 98.5%; 95% CI, 94.5–99.6) and osteopenia (sensitivity, 85.1%; 95% CI, 72.3–92.6 and specificity, 85.4%; 95% CI, 76.6–91.3). Of the 16 patients who had “fragile” bone strength by BCT (placing them at the equivalent high risk of fracture as for osteoporosis), 6 had osteoporosis and 10 had osteopenia by DXA.CONCLUSIONS:CTE scans can provide hip BMD, T-scores, and clinical classifications that are comparable to those obtained from DXA; when combined with BCT analysis, CTE can identify a subset of patients with osteopenia who have clinically relevant fragile bone strength. This technique could markedly increase bone health assessments in IBD patients already undergoing CTE to evaluate small bowel disease.

Magnetic Resonance Imaging of the Throwing Elbow in the Uninjured, High School–Aged Baseball Pitcher

Background: Tissue adaptations in response to pitching are an expected finding during magnetic resonance imaging (MRI) evaluation of the throwing elbow of adult pitchers. These changes are considered normal in the absence of symptom complaints. It is unclear when during the playing career these tissue adaptations are initiated. Hypothesis: Abnormalities in the appearance of the throwing elbow compared with the nonthrowing elbow would be visible during MRI assessment of this asymptomatic population of high school–aged throwers. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Twenty-three uninjured, asymptomatic male high school–aged baseball pitchers (mean age, 16 years) with no history of elbow injury were recruited for the study. Participants had a minimum of 3 years’ experience with pitching as their primary position (mean experience, 6 years). Bilateral elbow MRI examinations were performed using a standardized protocol including fast spin-echo proton-density (axial and coronal), T1-weighted (sagittal), and T2-weighted fat-saturated (axial, sagittal, and coronal) sequences. Osteoarticular, ligamentous, musculotendinous, and neural structures were evaluated and compared bilaterally. The images were reviewed by a musculoskeletal radiologist who was blinded to all the gathered data on these athletes, including limb dominance. Results: Three participants (13%) had no abnormalities. Fifteen individuals (65%) had asymmetrical anterior band ulnar collateral ligament thickening, including 4 individuals who also had mild sublime tubercle/anteromedial facet edema. Fourteen participants (61%) had posteromedial subchondral sclerosis of the ulnotrochlear articulation, including 8 (35%) with a posteromedial ulnotrochlear osteophyte, and 4 (17%) with mild posteromedial ulnotrochlear chondromalacia. Ten individuals (43%) had multiple abnormal findings in the throwing elbow. Conclusion: Thickening of the anterior band of the ulnar collateral ligament and posteromedial subchondral sclerosis of the trochlea are common findings in the high school–aged pitcher and may be considered normal clinical findings in the absence of symptom complaints. Other changes in tissue appearance of the throwing elbow are uncommon in this age group and should be regarded with a higher level of caution when evaluating for the presence of injury. An understanding of the MRI appearance of the uninjured youth pitcher is necessary for clinicians to distinguish between normal adaptations and the presence of injury.

Clinical effectiveness of single lumbar transforaminal epidural steroid injections

OBJECTIVES To assess the clinical effectiveness of single lumbar transforaminal epidural steroid injections (TFESIs) in subjects with radicular pain with or without radiculopathy. DESIGN Retrospective observational series. SETTING Single academic radiology pain management practice. SUBJECTS Two thousand twenty-four subjects undergoing single lumbar TFESIs at the L4-5, L5-S1, or S1 neural foramina. METHODS / OUTCOME MEASURES Subjects were assessed with a pain numerical rating scale (NRS, 0-10) and Roland-Morris disability questionnaire (R-M, 23-point Deyo modification) prior to TFESI and at 2 weeks and 2 months follow-up. Successful pain relief (responders) was defined as either ≥50% reduction in NRS or pain 0/10; functional success was defined as ≥40% reduction in R-M score. RESULTS There were statistically significant (P < 0.0001) reductions in mean NRS and R-M scores at 2 weeks and 2 months postinjection. For NRS, 40.9% were responders at 2 weeks and 45.6% at 2 months. For R-M, 31.9% were responders at 2 weeks and 41.3% at 2 months. The proportion of responders for NRS and R-M was higher when there was <3 months of pain (odds ratio 2-month NRS = 2.42 [95% confidence interval: 1.82, 3.24], odds ratio 2-month R-M = 2.61 [1.96, 3.48]). For subjects with <3 months of pain, the proportion of responders was 62.4% (56.5, 68.3%) for NRS and 59.3% (53.3, 65.3%) for R-M scores. CONCLUSIONS This retrospective observational study suggests TFESIs are clinically effective in the treatment of lumbar radicular pain. Subjects with a shorter duration of pain are more likely to achieve a successful outcome.

Safety and Efficacy of CT-Guided Transforaminal Cervical Epidural Steroid Injections Using a Posterior Approach

BACKGROUND AND PURPOSE: Image-guided cervical transforaminal epidural injections play an important role in the management of cervical radicular pain syndromes. The safety and efficacy of these injections via an anterolateral approach has been well-studied. The goal of this retrospective review was to determine the safety and efficacy of CT-guided transforaminal epidural injections by using a posterior approach. MATERIALS AND METHODS: Retrospective review of patient records was used to define VNPS and RMDI of patients undergoing CT-guided transforaminal cervical epidural injections between 2006 and 2010. Pain scores were recorded preprocedure, immediately postprocedure, at 2 weeks, and at 2 months. The RMDI was recorded preprocedure, at 2 weeks, and at 2 months. Data analysis of 247 patients was completed. Differences in VNPS scores and the RMDI were then compared on the basis of a CT-guided approach (anterolateral versus posterior). RESULTS: There was no statistical difference in the degree of pain relief and improvement in the RMDI between the CT-guided transforaminal anterolateral approach and the posterior approach at 2 weeks and at 2 months. Both groups demonstrated a statistically significant improvement in pain scores and the RMDI. Approximately 35% of patients in both groups demonstrated >50% pain relief at 2 months. There were no serious complications in either group. CONCLUSIONS: CT-guided transforaminal cervical epidural injections by using a posterior approach are safe and effective.

Accuracy of electromyography needle placement in cadavers: Non‐guided vs. ultrasound guided

Accuracy of needle electromyography is typically ensured by use of anatomical landmarks and auditory feedback related to voluntary activation of the targeted muscle; however, in certain clinical situations, landmarks may not be palpable, auditory feedback may be limited or not present, and targeting a specific muscle may be more critical. In such settings, image guidance might significantly enhance accuracy.

Neuroanatomic Considerations in Percutaneous Tumor Ablation

Percutaneous ablation is increasingly being used as focal therapy for tumors in the chest, abdomen, and pelvis, including tumors in proximity to neural structures. To ensure that tumor ablation is performed safely, knowledge of the regional neuroanatomy is particularly important because most relevant nerves are not visualized with the conventional imaging techniques used to guide ablation procedures. Familiarity with the expected course of nerves in commonly targeted areas is helpful in preventing inadvertent nerve injury and in accurately informing the patient of potential risks. In the chest and shoulder girdle, the brachial plexus as well as the phrenic, recurrent laryngeal, intercostal-subcostal, long thoracic, dorsal scapular, and suprascapular nerves may be encountered. Vulnerable neural structures in the abdomen and pelvis arise from the lumbar and sacral plexuses and include the femoral, obturator, sciatic, and pudendal nerves. Nerve protection and monitoring techniques should be used, when appropriate, to minimize the risk of neural injury during percutaneous tumor ablation and depend on the vulnerable nerve, the location of the targeted tumor, and the ablation device used for treatment. Nerves may be protected using displacement techniques, including instillation of air or fluid, insertion and insufflation of angioplastic or endoscopic balloons, and mechanical manipulation of the ablation device. Nerves may be monitored with cross-sectional imaging evaluation of the critical nerve or ablation zone, or with functional evaluation using electromyographic equipment or focused clinical examination. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg334125141/-/DC1.