Measuring and reporting of vertebral endplate bone marrow lesions as seen on MRI (Modic changes): recommendations from the ISSLS Degenerative Spinal Phenotypes Group.

PURPOSE: The positive association between low back pain and MRI evidence of vertebral endplate bone marrow lesions, often called Modic changes (MC), offers the exciting prospect of diagnosing a specific phenotype of chronic low back pain (LBP). However, imprecision in the reporting of MC has introduced substantial challenges, as variations in both imaging equipment and scanning parameters can impact conspicuity of MC. This review discusses key methodological factors that impact MC classification and recommends guidelines for more consistent MC reporting that will allow for better integration of research into this LBP phenotype. METHODS: Non-systematic literature review. RESULTS: The high diagnostic specificity of MC classification for a painful level contributes to the significant association observed between MC and LBP, whereas low and variable sensitivity underlies the between- and within-study variability in observed associations. Poor sensitivity may be owing to the presence of other pain generators, to the limited MRI resolution, and to the imperfect reliability of MC classification, which lowers diagnostic sensitivity and thus influences the association between MC and LBP. Importantly, magnetic field strength and pulse sequence parameters also impact detection of MC. Advances in pulse sequences may improve reliability and prove valuable for quantifying lesion severity. CONCLUSIONS: Comparison of MC data between studies can be problematic. Various methodological factors impact detection and classification of MC, and the lack of reporting guidelines hinders interpretation and comparison of findings. Thus, it is critical to adopt imaging and reporting standards that codify acceptable methodological criteria. These slides can be retrieved under Electronic Supplementary Material.

Percutaneous Rupture of Zygapophyseal Joint Synovial Cysts: A Prospective Assessment of Nonsurgical Management.

BACKGROUND: Although lumbar zygapophyseal joint synovial cysts are fairly well recognized, they are an uncommon cause of lumbosacral radicular pain. Nonoperative treatments include percutaneous aspiration of the cysts under computed tomography or fluoroscopic guidance with a subsequent corticosteroid injection. However, there are mixed results in terms of long-term outcomes and cyst reoccurrence. This study prospectively evaluates percutaneous ruptures of zygapophyseal joint (Z-joint) synovial cysts for the treatment of lumbosacral radicular pain. OBJECTIVES: Primary: To determine whether percutaneous rupture of symptomatic Z-joint synovial cysts leads to sustained improvements in radicular pain and function. Secondary: To assess the rates of cyst recurrence and progression to surgical intervention following percutaneous rupture of symptomatic Z-joint synovial cysts. DESIGN: Prospective cohort study. SETTING: Outpatient academic spine practice. PARTICIPANTS: Adults with primary radicular pain due to a facet synovial cyst. METHODS: Participants underwent fluoroscopically guided percutaneous Z-joint synovial cyst ruptures under standard-of-care practice. Data on pain, physical function, satisfaction, and progression to surgery were collected at 2 weeks, 6 weeks, 3 months, 6 months, and 1 year after rupture. An intention-to-treat analysis was used for assessment of patient-reported outcome measures. MAIN OUTCOME MEASURES: The Numerical Rating Scale, Oswestry Disability Index, and modified North American Spine Society questionnaires were used to measure pain, function, and satisfaction with the procedure, respectively. RESULTS: Thirty-five participants were included in the study, and data were analyzed by an independent researcher. Statistically significant changes in Oswestry Disability Index were reported at 2 weeks, 3 months, and 1 year postintervention (P = .034, .040, and .039, respectively). A statistically and clinically significant relief of current pain was reported at 2 weeks (P = .025) and 6 weeks (P = .014) with respect to baseline. Patients showed significant improvements for best pain at 6 weeks with respect to baseline (P = .031). Patients' worst pain showed the greatest amount of improvement with clinically meaningful changes at all time points compared with baseline. Patient-reported satisfaction was found nearly 70% of the time at all time points. Forty percent (14/35) of participants required repeat cyst rupture, and 31% (11/35) required surgical interventions. CONCLUSIONS: There were statistically and clinically significant improvements in pain and function after percutaneous rupture of Z-joint synovial cysts. In addition, the outcomes support previous retrospective studies indicating that approximately 40% of patients will need surgery. This study provides further research to determine the utility of this procedure and to precisely define a subset of ideal candidates. LEVEL OF EVIDENCE: Level II.

The intervertebral disc, the endplates and the vertebral bone marrow as a unit in the process of degeneration.

OBJECTIVES: The association of disc degeneration (DD) and vertebral endplate degeneration (EPD) is still not well understood. This study aimed to find segmental predictive risk factors for DD and EPD and to illuminate associations of the disc, endplate and bone marrow changes in the process of degeneration. METHODS: After institutional review board approval, 450 lumbar levels, followed up with MRI for at least 4 years, were retrospectively graded for DD according to Pfirrmann (PFG), for EPD according to the endplate score (EPS) and according to the presence, extension and type of Modic changes (MC). Clustered logistic regression and multivariate analysis was applied in nested, matched case-control subgroups to evaluate potential local risk factors for progression. RESULTS: An EPS score of ≥4 was identified as an independent risk factor for progression of DD (OR = 2.32, 95%CI:1.07-5.01,p = 0.03) and MC (OR = 5.49,95%CI:2.30-13.10,p < 0.001). Progression of DD was significantly accompanied by progression or evolution of MC (OR = 12.25,95%CI:1.49-100.6,p = 0.02) and with progression of EPS (OR = 1.71, 95%CI:1.00-1.05, p = 0.01). Once advanced DD has occurred, it becomes a risk factor for progression in EPS (OR = 2.24,95%CI:1.23-4.12,p < 0.01). CONCLUSIONS: The degenerative processes in the disc, endplate and bone marrow are highly associated. An EPS ≥ 4 is an independent risk factor for DD and MC progression in a population with low back pain. KEY POINTS: • The degenerative processes in the disc, endplate and bone marrow are associated. • An endplate score ≥4 is a risk factor for DD and MC progression. • Modic changes are last to occur in the development of segmental intervertebral degeneration. • A new segmental grading system is suggested.

A Novel Radiographic Indicator of Developmental Cervical Stenosis.

BACKGROUND: Developmental cervical stenosis of the spinal canal predisposes patients to neural compression and loss of function. The Torg-Pavlov ratio has been shown to provide high sensitivity but low specificity for identifying developmental cervical stenosis. A more sensitive and specific radiographic index has not been reported to our knowledge. The objective of this study was to develop and provide an objective, sensitive, and specific radiographic index to assess for developmental cervical stenosis. METHODS: The C3 through C6 levels of the cervical spine were analyzed on lateral radiographs of 150 adult patients to determine the spinolaminar line-to-lateral mass distance (SL), lateral mass-to-posterior vertebral body distance (LM), spinolaminar line-to-vertebral body (canal) diameter (CD), and vertebral body diameter (VB). Ratios of these measurements were calculated to eliminate magnification effects. The corresponding true spinal canal diameter was measured using computed tomography (CT) midsagittal sections. Receiver operating characteristic (ROC) curve analysis was performed to identify a radiographic measurement ratio with optimal sensitivity and specificity, using a true canal diameter of <12 mm to define developmental cervical stenosis. RESULTS: Several of the measured ratios demonstrated a strong correlation with the true canal diameter at all cervical levels. However, ROC curve analysis showed that only an LM/CD ratio of ≥0.735 indicated a canal diameter of <12 mm (developmental cervical stenosis). The sensitivity of this ratio at C5 was 83% and its specificity at C5 was 74%. An LM/CD ratio of ≥0.735 measured only at the C5 level also indicated developmental cervical stenosis at any cervical level from C3 through C6 with 76% sensitivity and 80% sensitivity. Other ratios, including the Torg-Pavlov ratio, did not demonstrate an adequate statistical profile to indicate developmental cervical stenosis. The accuracy of the LM/CD ratio was not adversely affected by the patient's sex. CONCLUSIONS: This analysis provided a novel index for identifying developmental cervical stenosis: the C5 lateral mass/canal diameter (LM/CD) ratio. We believe that this ratio is the best radiographic measurement available to screen for developmental cervical stenosis in the adult spine patient population. It provides an objective radiographic screening tool for physicians to detect developmental cervical stenosis and decide whether additional imaging or surgical referral is appropriate. LEVEL OF EVIDENCE: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Does provocative discography cause clinically important injury to the lumbar intervertebral disc? A 10-year matched cohort study.

BACKGROUND CONTEXT: Provocative discography, an invasive diagnostic procedure involving disc puncture with pressurization, is a test for presumptive discogenic pain in the lumbar spine. The clinical validity of this test is unproven. Data from multiple animal studies confirm that disc puncture causes early disc degeneration. A recent study identified radiographic disc degeneration on magnetic resonance imaging (MRI) performed 10 years later in human subjects exposed to provocative discography. The clinical effect of this disc degeneration after provocative discography is unknown. PURPOSE: The aim of this study was to investigate the clinical effects of lumbar provocative discography on patients subjected to this evaluation method. STUDY DESIGN/SETTING: A prospective, 10-year matched cohort study. PATIENT SAMPLE: Subjects (n=75) without current low back pain (LBP) problems were recruited to participate in a study of provocative discography at the L3-S1 discs. A closely matched control cohort was simultaneously recruited to undergo a similar evaluation except for discography injections. OUTCOME MEASURES: The primary outcome variables were diagnostic imaging events and lumbar disc surgery events. The secondary outcome variables were serious LBP events, disability events, and medical visits. METHODS: The discography subjects and control subjects were followed by serial protocol evaluations at 1, 2, 5, and 10 years after enrollment. The lumbar disc surgery events and diagnostic imaging (computed tomography (CT) or MRI) events were recorded. In addition, the interval and cumulative lumbar spine events were recorded. RESULTS: Of the 150 subjects enrolled, 71 discography subjects and 72 control subjects completed the baseline evaluation. At 10-year follow-up, 57 discography and 53 control subjects completed all interval surveillance evaluations. There were 16 lumbar surgeries in the discography group, compared with four in the control group. Medical visits, CT/MRI examinations, work loss, and prolonged back pain episodes were all more frequent in the discography group compared with control subjects. CONCLUSION: The disc puncture and pressurized injection performed during provocative discography can increase the risk of clinical disc problems in exposed patients.

Are all spine MRI studies created equal? Understanding and rewarding quality.

The high incidence of failed back patients in the United States calls for a closer look at the source of the problem. In this paper I examine how variability in quality at the diagnostic stage can contribute to the problem. Although MRIs are widely perceived to be a commodity, I identify three key factors that create variability in the quality of an MRI: imaging equipment, imaging protocols, and subspecialization of the reading radiologist. To evaluate the impact of these quality variables, I am collaborating with Spreemo to run a clinical trial at Hospital for Special Surgery to determine the relationship between MRI quality measures and treatment recommendations, and ultimately patient outcomes.

Associations between lumbosacral transitional anatomy types and degeneration at the transitional and adjacent segments.

BACKGROUND CONTEXT: The relation between specific types of lumbosacral transitional vertebra and the degree of degeneration at and adjacent to the transitional level is unclear. It is also unknown whether the adjacent cephalad segment to a transitional vertebra is prone to greater degeneration than a normal L5-S1 level. PURPOSE: The purpose of this study was to evaluate the relation between specific lumbosacral transitional vertebra subtypes according to the Castellvi classification, and to determine the severity of degeneration at the transitional level and the adjacent cephalad segment. STUDY DESIGN: This study was a retrospective review. PATIENT SAMPLES: Ninety-two subjects with lumbosacral transitional vertebra grade 2 or higher and 94 control subjects without were retrieved from a picture archiving and communication system (PACS) search. OUTCOME MEASURES: Disc degeneration parameters at the transitional and at the adjacent cephalad level were measured. METHODS: After institutional review board approval, 92 subjects (42 men; mean age, 57±16 years) with lumbosacral transitional vertebra grade 2 or higher and 94 control subjects (41 men; mean age, 51±16 years) without were retrieved from a PACS search. Degeneration of the last two segments of the lumbar spine was quantified using the Pfirrmann and Modic classifications, along with documentation of annular tears, disc herniations, and disc height, and were compared between the two groups. Furthermore, L5-S1 levels in the control subjects were compared with the adjacent cephalad segments of the transitional vertebrae for the same parameters. RESULTS: Although the control subjects, at L5-S1, had moderate to severe degeneration by Pfirrmann grades (31%) and Modic changes ([MC] 20%), in comparison, the discs at the transitional level of the lumbosacral transitional vertebra group demonstrated significant less degeneration (3% and 1%, respectively; each p<.05). The adjacent cephalad segments of the lumbosacral transitional vertebra group showed significantly greater degeneration (Pfirrmann grade 5, 39%; MC, 30%) compared with the L4-L5 level in control subjects (16% and 11%, respectively; each p<.05). The severity of disc degeneration using all parameters correlated with the type of lumbosacral transitional vertebra. The degree of degeneration of L5-S1 in control subjects was similar to the adjacent cephalad segment in lumbosacral transitional vertebrae. CONCLUSION: Increasing the mechanical connection of a lumbosacral transitional vertebra protects the disc at the transitional level and predisposes the adjacent cephalad segment to greater degeneration. The adjacent cephalad segment had a comparable degree of degeneration as the L5-S1 level in control subjects.

Merits of different anatomical landmarks for correct numbering of the lumbar vertebrae in lumbosacral transitional anomalies.

PURPOSE: Anatomical landmarks and their relation to the lumbar vertebrae are well described in subjects with normal spine anatomy, but not for subjects with lumbosacral transitional vertebra (LSTV), in whom correct numbering of the vertebrae is challenging and can lead to wrong-level treatment. The aim of this study was to quantify the value of different anatomical landmarks for correct identification of the lumbar vertebra level in subjects with LSTV. METHODS: After IRB approval, 71 subjects (57 ± 17 years) with and 62 without LSTV (57 ± 17 years), all with imaging studies that allowed correct numbering of the lumbar vertebrae by counting down from C2 (n = 118) or T1 (n = 15) were included. Commonly used anatomical landmarks (ribs, aortic bifurcation (AB), right renal artery (RRA) and iliac crest height) were documented to determine the ability to correctly number the lumbar vertebrae. Further, a tangent to the top of the iliac crests was drawn on coronal MRI images by two blinded, independent readers and named the 'iliac crest tangent sign'. The sensitivity, specificity and the interreader agreement were calculated. RESULTS: While the level of the AB and the RRA were found to be unreliable in correct numbering of the lumbar vertebrae in LSTV subjects, the iliac crest tangent sign had a sensitivity and specificity of 81 % and 64-88 %, respectively, with an interreader agreement of k = 0.75. CONCLUSION: While anatomical landmarks are not always reliable, the 'iliac crest tangent sign' can be used without advanced knowledge in MRI to most accurately number the vertebrae in subjects with LSTV, if only a lumbar spine MRI is available.

Spinal subdural hematoma following lumbar decompressive surgery: a report of two cases.

Spinal subdural hematoma (SSDH) following spine surgery is an extremely rare condition, with only three cases being reported in the literature. Unintended durotomy has been associated with SSDH due to alterations of pressures in the dural compartments. The objective of the present report was to report two rare cases of acute SSDH developed after lumbar decompressive surgery. In one of the patients, the diagnosis of SSDH was followed by urgent hematoma evacuation via durotomy due to the patient's worsening neurological symptoms. In the second patient, the SSDH was treated conservatively due to the absence of severe or progressive motor or sensory deficits. In conclusion, emergency evacuation via durotomy is the treatment of choice for patients with SSDH and neurologic impairment. Conservative management may be indicated in selected cases with absent motor and sensory deficits.

Is the iliolumbar ligament a reliable identifier of the L5 vertebra in lumbosacral transitional anomalies?

OBJECTIVE: Sufficiently sized studies to determine the value of the iliolumbar ligament (ILL) as an identifier of the L5 vertebra in cases of a lumbosacral transitional vertebra (LSTV) are lacking. METHODS: Seventy-one of 770 patients with LSTV (case group) and 62 of 611 subjects without LSTV with confirmed L5 level were included. Two independent radiologists using coronal MR images documented the level(s) of origin of the ILL. The interobserver agreement was analysed using weighted kappa/kappa (wκ/κ) and a Fischer's exact test to assess the value of the ILL as an identifier of the L5 vertebra. RESULTS: The ILL identified the L5 vertebra by originating solely from L5 in 95 % of the controls; additional origins were observed in 5 %. In the case group, the ILL was able to identify the L5 vertebra by originating solely from L5 in 25-38 %. Partial origin from L5, including origins from other vertebra was observed in 39-59 % and no origin from L5 at all in 15-23 % (wκ = 0.69). Both readers agreed that an ILL was always present and its origin always involved the last lumbar vertebra. CONCLUSION: The level of the origin of the ILL is unreliable for identification of the L5 vertebra in the setting of an LSTV or segmentation anomalies. KEY POINTS: • The origin of the ILL is evaluated in subjects with an LSTV. • The origin of the ILL is anatomically highly variable in LSTV. • The ILL is not a reliable landmark of the L5 vertebra in LSTV.

Determinants of evolution of endplate and disc degeneration in the lumbar spine: a multifactorial perspective.

PURPOSE: Evolution and progression of disc and endplate bone marrow degeneration of the lumbar spine are thought to be multifactorial, yet, their influence and interactions are not understood. The aim of this study was to find association of potential predictors of evolution of degeneration of the lumbar spine. METHODS: Patients (n = 90) who underwent two lumbar magnetic resonance imaging (MRI) exams with an interval of at least 4 years and without any spinal surgery were included into the longitudinal cohort study with nested case-control analysis. Disc degeneration (DD) was scored according to the Pfirrmann classification and endplate bone marrow changes (EC) according to Modic in 450 levels on both MRIs. Potential variables for degeneration such as age, gender, BMI, scoliosis and sagittal parameters were compared between patients with and without evolution or progression of degenerative changes in their lumbar spine. A multivariate analysis aimed to identify the most important variables for progression of disc and endplate degeneration, respectively. RESULTS: While neither age, gender, BMI, sacral slope or the presence of scoliosis could be identified as progression factor for DD, a higher lordosis was observed in subjects with no progression (49° ± 11° vs 43° ± 12°; p = 0.017). Progression or evolution of EC was only associated with a slightly higher degree of scoliosis (10° ± 10° vs 6° ± 9°; p = 0.04) and not to any of the other variables. CONCLUSION: While a coronal deformity of the lumbar spine seems associated with evolution or progression of EC, a higher lumbar lordosis is protective for radiographic progression of DD. This implies that scoliotic deformity and lesser lumbar lordosis are associated with higher overall degeneration of the lumbar spine.

Is an annular tear a predictor for accelerated disc degeneration?

PURPOSE: It is questionable whether an annular tear (AT) is a predictor for accelerated degeneration of the intervertebral discs. The aim of the present study was to answer this question via a matched case-control study design that reliably eliminates potential confounders. MATERIALS: Presence or absence of AT, defined as a hyperintense lesion within the annular fibrosus on T2-weighted non-contrast MRI images, was documented in 450 intervertebral lumbar discs of 90 patients who could be followed up for at least 4 years with MRI. Discs with an AT (n = 36) were matched 1:1 to control discs according to the level, degree of initial disc degeneration on MRI (both Pfirrmann grade median 4, range 3-4), age (59.5 ± 15.0 versus 59.3 ± 14.6 years), BMI (26.7 ± 4.4 versus 26.9 ± 4.4 kg/m(2)) and interval to the follow-up MRI (4.8 ± 0.9 versus 5.1 ± 0.8 years). The degree of disc degeneration after a minimum of 4 years was graded on the follow-up MRI in both groups according to the Pfirrmann classification. RESULTS: One-fourth (25%) of the 36 discs with an AT on the initial MRI exam progressed in degeneration. This was similar to the rate of the matched control discs with no AT, in which also around one-fourth (22%) showed a progression of degeneration (p = 1.00), also without any difference in the degree of degeneration. CONCLUSION: Discs with a Pfirrmann grade >2 with an AT, defined by a hyperintense signal intensity on MRI, are not prone to accelerated degeneration if compared to discs without an AT. Therefore, the presence of an AT per se does not predict accelerated disc degeneration.

Interreader and intermodality reliability of standard anteroposterior radiograph and magnetic resonance imaging in detection and classification of lumbosacral transitional vertebra.

BACKGROUND CONTEXT: Different types of lumbosacral transitional vertebra (LSTV) are classified based on the relationship of the transverse process of the last lumbar vertebra to the sacrum. The Ferguson view (30° angled anteroposterior [AP] radiograph) is supposed to have a sufficient interreader reliability in classification of LSTV, but is not routinely available. Standard AP radiographs and magnetic resonance imaging (MRI) are often available, but their reliability in detection and classification of LSTV is unknown. PURPOSE: The purpose of this study was to evaluate the interreader reliability of detection and classification of LSTV with standard AP radiographs and report its accuracy by use of intermodality statistics compared with MRI as the gold standard. STUDY DESIGN/SETTING: Retrospective case control study. PATIENT SAMPLE: A total of 155 subjects (93 cases: LSTV type 2 or higher; 62 controls). OUTCOME MEASURES: Interreader reliability in detection and classification of LSTV using standard AP radiographs and coronal MRI as well as accuracy of radiographs compared with MRI. METHODS: After institutional review board approval, coronal MRI scans and conventional AP radiographs of 155 subjects (93 LSTV type 2 or higher and 62 controls) were retrospectively reviewed by two independent, blinded readers and classified according to the Castellvi classification. Interreader reliability was assessed using kappa statistics for detection of an LSTV and identification of all subtypes (six variants; 1: no LSTV or type I, 2: LSTV type 2a, 3: LSTV type 2b, 4: LSTV type 3a, 5: LSTV type 3b, 6: LSTV type 4) for MRI scans and standard AP radiographs. Further, accuracy and positive and negative predictive values were calculated for standard AP radiographs to detect and classify LSTV using MRI as the gold standard. RESULTS: The interreader reliability was at most moderate for the detection (k=0.53) and fair for classification (wk=0.39) of LSTV in standard AP radiograph. However, the interreader reliability was very good for detection (k=0.93) and classification (wk=0.83) of LSTV in MRI. The accuracy and positive and negative predictive values of standard AP radiograph were 76% to 84%, 72% to 86%, and 79% to 81% for the detection and 53% to 58%, 51% to 76%, and 49% to 55% for the classification of LSTV, respectively. CONCLUSION: Standard AP radiographs are insufficient to detect or classify LSTV. Coronal MRI scans, however, are highly reliable for classification of LSTV.

Magnetic resonance imaging predictors of surgical outcome in patients with lumbar intervertebral disc herniation.

STUDY DESIGN: A retrospective cohort design. OBJECTIVE: To determine whether baseline magnetic resonance imaging findings, including central/foraminal stenosis, Modic change, disc morphology, facet arthropathy, disc degeneration, nerve root impingement, and thecal sac compression, are associated with differential surgical treatment effect. SUMMARY OF BACKGROUND DATA: Intervertebral disc herniation remains the most common source of lumbar radiculopathy treated either with discectomy or nonoperative intervention. Although magnetic resonance imaging remains the reliable "gold standard" for diagnosis, uncertainty surrounds the relationship between magnetic resonance imaging findings and treatment outcomes. METHODS: Three hundred seven "complete" images from patients enrolled in a previous trial were de-identified and evaluated by 1 of 4 independent readers. Findings were compared with outcome measures including the Oswestry Disability Index. Differences in surgery and nonoperative treatment outcomes were evaluated between image characteristic subgroups and TE determined by the difference in Oswestry Disability Index scores. RESULTS: The cohort comprised 40% females with an average age of 41.5 (±11.6) years, 61% of whom underwent discectomy for intervertebral disc herniation. Patients undergoing surgery with Modic type I endplate changes had worse outcomes (-26.4 vs. -39.7 for none and -39.2 for type 2, P = 0.002) and smaller treatment effect (-3.5 vs. -19.3 for none and -15.7 for type 2, P = 0.003). Those with compression of ≥1/3 showed the greatest improvement within the surgical group (-41.9 for ≥1/3 vs. -31.6 for none and -38.1 for <1/3, P = 0.007) and the highest TE (-23 compared with -11.7 for none and -15.2 for <1/3, P = 0.015). Furthermore, patients with minimal nerve root impingement demonstrated worse surgical outcomes (-26.5 vs. -41.1 for "displaced" and -38.9 for "compressed," P = 0.016). CONCLUSION: Among patients with intervertebral disc herniation, those with thecal sac compression of 1/3 or more had greater surgical treatment effect than those with small disc herniations and Modic type I changes. In addition, patients with nerve root "compression" and "displacement" benefit more from surgery than those with minimal nerve root impingement. LEVEL OF EVIDENCE: 2.

Comparison of a fluoroscopic 3-dimensional imaging system and conventional CT in detection of pars fractures in the cadaveric lumbar spine.

STUDY DESIGN: Cadaveric Study. OBJECTIVE: To compare a fluoroscopic imaging system with computed tomography (CT) and radiographs in detection of spondylolysis and radiation exposure in a cadaver model. SUMMARY OF BACKGROUND DATA: Lumbar spondylolysis is defined as a defect or fracture of the pars interarticularis and occurs with or without anterior spondylolisthesis. CT scan is the gold standard imaging study for spondylolysis but is limited by the supine position, which may cause reduction of anterolisthesis and by ionizing radiation, which limits the frequency of follow-up scans. METHODS: Thirteen intact cadaveric lumbar spine segments with 26 pars were randomized to be left intact or to undergo simulated fracture using a 1.3 mm oscillating microsurgical saw. Fifteen pars underwent simulated fracture and 11 pars were left intact. Lumbar spine segments were imaged using plain radiographs, multiplanar fluoroscopic imaging, and conventional CT scan. The images were interpreted by 3 observers blinded to the number and location of defects. Radiation exposure and doses were recorded from all imaging units. RESULTS: Average radiation doses were 0.0025 mSv for each radiograph, 0.23 mSv (low dose) and 0.47 mSv (high dose) for fluoroscopic imaging, and 1.5 mSv for conventional CT imaging (pediatric dose setting). Evaluation of radiographs for spondylolysis had sensitivity of 98% and specificity of 97%. Evaluation using low-dose fluoroscopic images, high-dose fluoroscopic images, and CT scan images correctly identified the status of all pars based on multiplanar images; sensitivity and specificity were 100%. Kappa analysis demonstrated a value of 0.89 for radiographic interpretation indicating excellent agreement. Kappa values describing agreement for image interpretation for fluoroscopic imaging and CT scan were equal to 1.0, representing perfect agreement. CONCLUSIONS: Three-dimensional fluoroscopic imaging provides comparable diagnostic imaging with CT scan in an experimental cadaveric model of spondylolysis using up to 85% less radiation than conventional CT scan.