Magnetic Resonance Imaging Cross-sectional Area Research Articles

Diagnostic accuracy of ultrasound and MR imaging in peroneal neuropathy: A prospective, single-center study.

Magnetic resonance imaging (MRI) findings in peroneal neuropathy are not well documented and the prognostic value of imaging remains uncertain. Upper limits of cross-sectional area (CSA) on ultrasound (US) have been established, but uncertainty regarding generalizability remains. We aimed to describe MRI findings of the peroneal nerve in patients and healthy controls and to compare these results to US findings and clinical characteristics. We prospectively included patients with foot drop and electrodiagnostically confirmed peroneal neuropathy, and performed clinical follow-up, US and MRI of both peroneal nerves. We compared MRI findings to healthy controls. Two radiologists evaluated MRI features in an exploratory analysis after images were anonymized and randomized. Twenty-two patients and 38 healthy controls were included. Whereas significant increased MRI CSA values were documented in patients (mean CSA 20 mm2 vs. 13 mm2 in healthy controls), intra- and interobserver variability was substantial (variability of, respectively, 7 and 9 mm2 around the mean in 95% of repeated measurements). A pathological T2 hyperintense signal of the nerve was found in 52.6% of patients (50% interobserver agreement). Increased CSA measurements (MRI/US), pathological T2 hyperintensity of the nerve and muscle edema were not predictive for recovery. Imaging is recommended in all patients with peroneal neuropathy to exclude compressive intrinsic and extrinsic masses but we do not advise routine MRI for diagnosis or prediction of outcome in patients with peroneal neuropathy due to high observer variability. Further studies should aim at reducing MRI observer variability potentially by semi-automation.

Clinical Efficacy of Large-Channel Percutaneous Lumbar Endoscopic Decompression in the Treatment of Lumbar Spinal Stenosis Secondary to Old Compression Fractures

We sought to explore the clinical efficacy of lumbar spinal stenosis (LSS) secondary to old vertebral compression fractures (OVCF) treatment by large-channel percutaneous endoscopic lumbar decompression. Medical data for a total of 17 patients diagnosed with LSS secondary to OVCF and treated with large-channel percutaneous endoscopic lumbar decompression in our institution from January 2019 to January 2021 were collected. The dural sac cross-sectional area and morphologic grading of the magnetic resonance imaging cross-sectional area were recorded. Lumbar spine stability was assessed using the White-Panjabi scoring system. Visual analog scale and Japanese Orthopaedic Association scores were used to evaluate the surgical efficacy, and the SF-36 health questionnaire was used to evaluate the quality of life of patients. Type and probability of complications were also recorded. The operative segments of the enrolled patients were all in the lower lumbar spine. One-year follow-up post operation showed that the dural sac cross-sectional area was significantly enlarged compared with preoperation, and the morphologic grade was significantly improved (P < 0.05). There was no difference in White-Panjabi score between preoperation and postoperation (P > 0.05). Visual analog scale and Japanese Orthopaedic Association scores at each follow-up time point after operation were higher than those before operation and were significantly improved (P < 0.05). The SF-36 health survey score at 1 year after operation was significantly higher than that before operation (P < 0.05). The complication rate was 6%. Large-channel percutaneous lumbar endoscopic decompression has an evident clinical effect in the treatment of LSS secondary to OVCF and has little effect on the stability of the lumbar spine, which is worthy of clinical application.

Validity of ultrasound imaging for intrinsic foot muscle cross-sectional area measurements demonstrated by strong agreement with MRI

PurposeIntrinsic foot muscles maintain foot structural integrity and contribute to functional movement, posture and balance. Thus, assessing intrinsic foot muscle size and strength are important. Magnetic resonance imaging (MRI) has been shown to accurately image the individual muscles but is costly and time consuming. Ultrasound (US) imaging may provide an alternative that is less costly and more readily available. The purpose of this study was to investigate the validity and intratester reliability of US imaging in measuring intrinsic foot muscle size in comparison to MRI.MethodsUS and MRI were employed to measure the intrinsic foot muscle size involving 35 participants (females = 13; males = 22). The scanned intrinsic foot muscles included the flexor hallucis brevis (FHB), abductor hallucis (ABDH), flexor digitorum brevis (FDB), quadratus plantae (QP) and abductor digiti minimi (ADM). Pearson product correlation (r), intraclass correlation coefficients (ICC), standard error of the measurement (SEm) and minimal detectable difference (MDD) were calculated.ResultsHigh correlations were detected between the US and MRI cross-sectional area (CSA) measurements (r = .971 to 0.995). Test reliability was excellent for both MRI and US (ICC = 0.994 to 0.999). Limits of agreement between MRI and US measurements from ranged from 5.7 to 12.2% of muscle size. SEm values for US ranged from 0.026 to 0.044 cm2, while the SEm for MRI ranged from 0.018 to 0.023 cm2. MDD values for US ranged from 0.073 to 0.122 cm2, while MRI ranged from 0.045 to 0.064 cm2.ConclusionsUS appears to be a valid and reliable alternative to MRI when measuring intrinsic foot muscle CSA. While US is less costly and more readily available, the MRI results were shown to be slightly more precise.

Comparing Absorbable and Nonabsorbable Suture Materials for Repair of Achilles Tendon Rupture: A Magnetic Resonance Imaging-Based Study.

We aimed to compare magnetic resonance imaging (MRI) findings and corresponding clinical outcomes of repaired Achilles tendons using absorbable and nonabsorbable sutures. Patients who underwent Achilles tendon repair were divided into 2 groups, with 11 in the absorbable group (group A) and 11 in the nonabsorbable group (group B). For all patients, MRI findings taken 6 months postoperatively were evaluated for morphological changes in the tendon. Concurrently, the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hind foot score and incidence of postoperative complications were evaluated. Regarding MRI findings, the extent to which the cross-sectional area of the repaired tendon was thicker than that of the preoperative tendon was significantly greater in group B than in group A (p = 0.0012). Notably, more stitches remained within the tendon in group B than in group A (p = 0.0063). No other MRI findings showed a significant difference between the two groups. No significant difference was observed in the AOFAS score, and there was one re-rupture each in both groups. Because nonabsorbable suture material in the treatment of Achilles tendon rupture yielded a thicker postoperative MRI cross-sectional area, enhanced rehabilitation is recommended in order to prevent scar formation.

Effects of Intraoperative Magnetic Resonance Thermal Imaging Signal Artifact During Laser Interstitial Thermal Therapy on Thermal Damage Estimate and Postoperative Magnetic Resonance Imaging Ablative Area Concordance.

Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive procedure that utilizes intraoperative magnetic resonance thermal imaging (MRTI) to generate a thermal damage estimate (TDE) of the ablative area. In select cases, the MRTI contains a signal artifact or defect that distorts the ablative region. No study has considered the impact of this artifact on TDE accuracy. To determine the effect of intraoperative MRTI signal artifact on postoperative magnetic resonance imaging (MRI)-predicted ablative area. All ablations were performed using the Visualase MRI-Guided Laser Ablation System (Medtronic). Patients were grouped based on whether the intraoperative MRTI contained signal artifact that distorted the ablative region. Cross-sectional area of the ablative lesion from the MRI image was measured, and the difference between intraoperative TDE and postoperative MRI cross-sectional area was calculated and compared between groups with and without intraoperative MRTI artifact. A total of 91 patients undergoing MRgLITT for various surgical indications were examined. MRTI artifact was observed in 43.9% of cases overall. The mean absolute difference between TDE and the postoperative MRI cross-sectional area was 94.8 mm2 (SEM=11.6) in the group with intraoperative MRTI artifact and 54.4 mm2 (SEM=5.5) in the nonartifact group. MRTI signal artifact is common during LITT. The presence of signal artifact during intraoperative MRTI results in higher variation between intraoperative TDE and postoperative MRI cross-sectional ablative area. In cases in which intraoperative MRTI artifact is observed, there may be a larger degree of variation between observed intraoperative TDE and measured postoperative MRTI ablative area.

Comparison of MRI cross-sectional area and functions of core muscles among asymptomatic individuals with and without lumbar intervertebral disc degeneration

BackgroundPrevious studies suggested that patients with symptomatic intervertebral disc degeneration (IDD) of lumbar spine have reduced cross-sectional area (CSA) and functions of core muscles. However, reduced CSA and functions of core muscles have been observed not only in patients with symptomatic IDD but also in patients with other subgroups of low back pain (LBP). Thus, it is uncertain whether reduced CSA and functions of core muscles lead to IDD and LBP, or pain leads to reduced CSA and functions of core muscles in patients with symptomatic IDD. Therefore, this study aimed to compare the CSA and functions of core muscles between asymptomatic participants with and without IDD in magnetic resonance imaging (MRI).MethodsTwenty asymptomatic participants (12 men and 8 women) participated in this study. Ten participants had asymptomatic IDD at L4–5. The others were healthy controls (without IDD at all levels of lumbar spine). The CSA of core muscles was measured using MRI. Maximal isometric trunk flexor strength and side bridge strength were measured by a Smart KEMA strength sensor. Trunk flexor endurance test, side bridge endurance test and plank endurance test were used to measure core endurance. Double legs loading test was used to measure core stability. Mann-Whitney U test was used to compare the differences between two groups.ResultsThere were no significant differences in core muscle functions between the two groups (p > 0.05). Moreover, there was no significant difference in CSA between the two groups (p > 0.05).ConclusionsThere was no significant difference in CSA and core muscle functions between asymptomatic participants with and without IDD. These findings indicate that a degenerative or bulging disc in asymptomatic individuals has little effect on CSA and functions of core muscles, especially in young age. Therefore, the general core endurance test or strength test could not differentiate asymptomatic people with and without IDD of lumbar spine.Trial registration numberClinical Research information Service. KCT0004061. Registered 13 June 2019. retrospectively registered.

Reliability of Magnetic Resonance Imaging Prediction of Anterior Cruciate Ligament Autograft Size and Comparison of Radiologist and Orthopaedic Surgeon Predictions.

Background:In anterior cruciate ligament (ACL) reconstruction, hamstring tendon autografts <8 mm have been associated with increased failure rates. There has been no established modality by which orthopaedic surgeons can preoperatively predict graft sizes.Purpose/Hypothesis:The purposes of this study were to (1) determine whether routine magnetic resonance imaging (MRI) measurement of hamstring tendon cross-sectional area (CSA) can reliably be used by sports medicine fellowship–trained orthopaedic surgeons to predict graft size and (2) determine whether radiologists and sports medicine surgeons are able to discriminate grafts below a predetermined cutoff value. We hypothesized that radiologists will find a correlation between MRI measurement and intraoperative graft size. Similarly, orthopaedic surgeons will be able to correctly estimate the graft size based on MRI measurement.Study Design:Cohort study (diagnosis); Level of evidence, 2.Methods:Included in this study were 30 consecutive patients (15 women and 15 men) (mean age, 23 years [range, 13-43 years]) for whom MRI-determined hamstring tendon CSA and graft size measurements could be compared. Patients were included if they had a preoperative MRI demonstrating acute ACL rupture and were scheduled with 1 of 3 surgeons for a reconstruction performed using the ST and GR tendons. Operative data were collected over 1 year. Sectra imaging software was used to measure the CSA of the semitendinosus (ST) and gracilis (GR) tendons on the preoperative MRIs. Control measurements were performed intraoperatively using a graft sizing block with 0.5-mm increments. Simple linear regression analysis was used to evaluate the ability of MRI measurements to predict autograft size. Logistic regression was used to determine the minimum CSA for a graft of 8 mm. The intraclass correlation coefficient (ICC) was used to evaluate interrater reliability.Results:MRI CSA measurement of the average STGR (ST CSA added to the GR CSA) was a significant predictor of graft size (adjusted R 2 = 0.186; P < .001). The 3 measurements with the strongest correlations with graft size were the ST at the medial femoral condyle (MFC), the STGR at the MFC, and the average STGR. The minimum CSA for the average STGR on MRI to achieve a graft size of 8 mm was 17.168 mm2 (P < .001). The area under the receiver operating characteristic curve was 0.765. The overall ICC was 0.977.Conclusion:Routine preoperative MRI can be used by both radiologists and orthopaedic surgeons to predict the expected ACL autograft size and identify those below a cutoff of 8 mm. This will help in preoperative planning and graft selection.

Predictive Factors for Hamstring Autograft Diameter in Anterior Cruciate Ligament Reconstruction.

Multiple studies found hamstring tendon (HT) autograft diameter to be a risk factor for anterior cruciate ligament (ACL) reconstruction failure. This study aimed to determine which preoperative measurements are associated with HT autograft diameter in ACL reconstruction by directly comparing patient characteristics and cross-sectional area (CSA) measurement of the semitendinosus and gracilis tendon on magnetic resonance imaging (MRI). Fifty-three patients with a primary ACL reconstruction with a four-stranded HT autograft were included in this study. Preoperatively we recorded length, weight, thigh circumference, gender, age, preinjury Tegner activity score, and CSA of the semitendinosus and gracilis tendon on MRI. Total CSA on MRI, weight, height, gender, and thigh circumference were all significantly correlated with HT autograft diameter (p < 0.05). A multiple linear regression model with CSA measurement of the HTs on MRI, weight, and height showed the most explained variance of HT autograft diameter (adjusted R 2 = 44%). A regression equation was derived for an estimation of the expected intraoperative HT autograft diameter: 1.2508 + 0.0400 × total CSA (mm2) + 0.0100 × weight (kg) + 0.0296 × length (cm). The Bland and Altman analysis indicated a 95% limit of agreement of ± 1.14 mm and an error correlation of r = 0.47. Smaller CSA of the semitendinosus and gracilis tendon on MRI, shorter stature, lower weight, smaller thigh circumference, and female gender are associated with a smaller four-stranded HT autograft diameter in ACL reconstruction. Multiple linear regression analysis indicated that the combination of MRI CSA measurement, weight, and height is the strongest predictor.

Lower extremity muscle structure in incomplete spinal cord injury: a comparison between ultrasonography and magnetic resonance imaging.

Ultrasound (US) measures of muscle thickness are used in the management and monitoring of muscle changes during rehabilitation, but it is unknown how this measure compares to magnetic resonance imaging (MRI) measures of muscle cross-sectional area (CSA) in patients with spinal cord injury (SCI). Six participants with incomplete SCI underwent US imaging and MRI of their gastrocnemius and tibialis anterior (TA) muscles. Significant correlations were found between US muscle thickness and MRI CSA in the gastrocnemius (R=0.91, P<0.001), and TA muscles (R=0.58, P<0.05). US muscle thickness in the gastrocnemius and TA of patients with incomplete SCI may be used as a cheaper alternative measure of CSA as measured using MRI, and this measure may be clinically useful to track progress in muscle gains during rehabilitation.

Panoramic ultrasound: a novel and valid tool for monitoring change in muscle mass.

BackgroundThe strong link between reduced muscle mass and morbidity and mortality highlights the urgent need for simple techniques that can monitor change in skeletal muscle cross‐sectional area (CSA). Our objective was to examine the validity of panoramic ultrasound to detect change in quadriceps and gastrocnemius size in comparison with magnetic resonance imaging (MRI) in subjects randomized to 70 days of bed rest (BR) with or without exercise.MethodsPanoramic ultrasound and MRI images of the quadriceps and gastrocnemius muscles were acquired on the right leg of 27 subjects (26 male, 1 female; age: 34.6 ± 7.8 years; body mass: 77.5 ± 10.0 kg; body mass index: 24.2 ± 2.8 kg/m2; height: 179.1 ± 6.9 cm) before (BR‐6), during (BR3, 7, 11, 15, 22, 29, 36, 53, 69), and after (BR+3, +6, +10) BR. Validity of panoramic ultrasound to detect change in muscle CSA was assessed by Bland–Altman plots, Lin's concordance correlation coefficient (CCC), sensitivity, specificity, positive predictive value, and negative predictive value.ResultsSix hundred ninety‐eight panoramic ultrasound CSA and 698 MRI CSA measurements were assessed. Concordance between ultrasound and MRI was excellent in the quadriceps (CCC: 0.78; P < 0.0001), whereas there was poor concordance in the gastrocnemius (CCC: 0.37; P < 0.0006). Compared with MRI, panoramic ultrasound demonstrated high accuracy in detecting quadriceps atrophy and hypertrophy (sensitivity: 73.7%; specificity: 74.2%) and gastrocnemius atrophy (sensitivity: 83.1%) and low accuracy in detecting gastrocnemius hypertrophy (specificity: 33.0%).ConclusionsPanoramic ultrasound imaging is a valid tool for monitoring quadriceps muscle atrophy and hypertrophy and for detecting gastrocnemius atrophy.

Anterior Cruciate Ligament Reconstruction With Autologous Hamstring: Can Preoperative Magnetic Resonance Imaging Accurately Predict Graft Diameter?

Background:Recent clinical investigations have identified inadequate autograft hamstring graft diameter (<8 mm) to be predictive of failure after reconstruction of the anterior cruciate ligament (ACL).Purpose/Hypothesis:The objective of this study was to determine the utility of preoperative magnetic resonance imaging (MRI) variables of the hamstring tendons for the prediction of graft diameter at the time of surgery. The hypothesis was that cross-sectional area (CSA) of the hamstring tendon measured on MRI could accurately predict graft diameter, and threshold measurements could be established to predict graft diameter at the time of surgery.Study Design:Cohort study (diagnosis); Level of evidence, 2.Methods:A total of 84 consecutive skeletally mature patients prospectively enrolled in our ACL reconstruction patient registry were identified for study purposes. Patients were included if they underwent an MRI of the affected knee at our institution prior to ACL reconstruction with hamstring (HT) autograft. Graft preparation was performed via a standard quadrupled hamstring technique after harvesting both the gracilis and semitendinosus (4-GST). The smallest diameter end of the HT autograft was then utilized for measurement analysis. Total CSA was calculated for both hamstring tendons using the “region of interest tool” on the corresponding proton density–weighted axial image of the knee at the widest condylar dimension. Three independent reviewers measured the MRI scans so that intra- and interrater reliability of the measurements could be determined. A trend analysis was then undertaken to establish correlations between the MRI CSA and graft diameter. Predictive analysis was then performed to establish threshold MRI measurement values for specific graft diameters and determine whether any patient-specific factors would affect graft diameter (age, sex, and body mass index).Results:Mean patient age at the time of surgery was 36 years (range, 11-57 years). Intra- and interrater reliability measurements achieved near-perfect agreement for CSA measurements, with intraclass correlation coefficients (ICCs) of 0.994 and 0.932, respectively. Trend analysis demonstrated that increasing CSA correlated well with increasing overall diameter of the graft (P < .001). Receiver operating characteristic (ROC) curves were generated to evaluate threshold CSA measurements for various graft diameters. Maximum sensitivity values of 21.64, 25.25, and 28.256 mm2 were established for the respective graft diameters of 8, 9, and 10 mm in the 4-GST group. Independent patient factors of younger age, shorter stature, and female sex were significantly associated with graft diameter (P = .019, .034, and .028, respectively).Conclusion:Preoperative MRI can be used to accurately predict quadrupled hamstring autograft diameter at the time of surgery. A total cross-sectional area of >22 mm2 can reliably provide a graft diameter of >8 mm at the time of surgery.

Correlation between semitendinosus and gracilis tendon cross-sectional area determined using ultrasound, magnetic resonance imaging and intraoperative tendon measurements

The purpose of this study was to examine the correlation in semitendinosus (ST) and gracilis (GT) tendon cross-sectional area (CSA) evaluated directly during anterior cruciate ligament (ACL) surgery and pre-operatively using ultrasound (US) and magnetic resonance imaging (MRI). A total of 14 patients undergoing ACL reconstruction with a quadruple ST–GT graft by the same orthopaedic surgeon participated in this study. Pre-operative evaluation included determination of ST and GT CSA area using US and MRI. Intraoperative measurement of the diameters of the ST, GT and the final ACL graft using a closed-hole sizing block with 0.5-mm increments was made and this diameter was used to estimate tendon CSA. The correlation between graft diameter and CSA were 0.563 (GT) and 0.807 (ST) for MRI and 0.498 (GT) and 0.612 (ST) for US. The final ACL graft diameter displayed a correlation coefficient of 0.813 with MRI CSA and 0.518 with US CSA. No differences in CSA were observed between intraoperative, MRI and US methods (p>0.05). The intraclass correlation coefficients between the US, MRI and intraoperative graft methods for the ST and GT data ranged from 0.502 to 0.903 with an estimation error ranging from 1.41% to 2.26%. These results indicate that in clinical situations where MRI is contra-indicated or not accessible, US can provide measurable values which could predict sufficient diameter of the ACL graft. In addition, determination of tendon CSA using US displays errors less than 2% which is similar to that observed using MRI. This suggests that the application of US can be applied to in vivo examination of the ST and GT CSA.

Can diagnostic ultrasound measure quadriceps size and vastus medialis to vastus lateralis ratio in patellofemoral pain syndrome?

Introduction: Discrepencies in size between vastus medialis (VM) and the rest of the quadriceps musculature (vastus intermedius (VI), vastus lateralis (VL), and rectus femoris (RF)) are thought to be present in a population with patellofemoral pain syndrome (PFPS). Thickness measures with diagnostic ultrasound could provide a cheap, time efficient method of measuring individual quadriceps muscle size for research and clinical purposes. This study aimed todetermine the validity of ultrasound inmeasuring individual quadricepsmuscle thickness by comparing results to magnetic resonance imaging (MRI) measures of muscle thickness and cross sectional area (CSA). Methods: Three female and two male participants with unilateral PFPS underwent bilateral ultrasound and MRI scanning of the quadriceps. Points were marked on the skin bilaterally over the mid-belly of VM, VL, VI, RF, and VMO. Comparisons were drawn for eachmuscle between ultrasoundmuscle thickness (USMT), and MRI muscle thickness (MRIMT) and CSA at these points. Pearson’s correlation coefficient (r) and intraclass correlation coefficient (ICC) using a random effects model (absolute agreement) were used to compare USMT and MRIMT, and compare the thickness ratio for MRI and US of VM:VL and VMO:VL. Spearman’s correlation coefficient (rho) was used to compare USMT with MRI CSA. Results: Ultrasound thickness measures were significantly correlated to MRIMT for VMO (r=0.86, ICC=0.63), VM (r=0.86, ICC=0.43), VL (r=0.94, ICC=0.81), and RF (r=0.86, ICC=0.71), no significant correlation was found for VI (r=0.37, ICC=0.24). The ratio of thickness between muscles for MRI and ultrasound were significantly correlated for VM:VL (r=0.86, ICC=0.82) and VMO:VL (r=0.92, ICC=0.921). Ultrasound thickness measures were significant correlated to MRI CSA measures for VM (rho=0.73), VL (rho=0.83), and RF (rho=0.88), and no significant correlation was found for VMO (rho=0.20) and VI (rho=0.310). Conclusion: Significant correlations were found for VM, VL and RF between USMT andMRI measures of muscle thickness and CSA, indicating these measures can be used to measure muscle size. The VMO USMT measure was significantly correlated to MRIMT but not to MRI CSA, and the VI USMT measure was not significantly correlated to either MRIMT or MRI CSA. Caution is advised in interpretation of these results as the small sample size in this study highlights the risk of type II error. Significant correlations were found between MRI and Ultrasound muscle thickness ratios for VM:VL and VMO:VL, indicating these measures may be useful for investigating if a difference is present in the size of VM and VL in PFPS.

Effect of Prehabilitation on the Outcome of Anterior Cruciate Ligament Reconstruction

Background: Prehabilitation is defined as preparing an individual to withstand a stressful event through enhancement of functional capacity. Hypothesis: We hypothesized that a preoperative exercise program would enhance postoperative outcomes after anterior cruciate ligament reconstruction (ACLR). Study Design: Randomized controlled clinical trial; Level of evidence, 1. Methods: Twenty volunteers awaiting ACLR were randomly assigned to a control or exercise intervention group. The exercise group completed a 6-week gym- and home-based exercise program. Assessments include single-legged hop test; quadriceps and hamstring peak torque and magnetic resonance imaging cross-sectional area (CSA); Modified Cincinnati Knee Rating System score; and muscle biopsy of the vastus lateralis muscle completed at baseline, preoperatively, and 12 weeks postoperatively. Myosin heavy chain (MHC) isoforms protein and messenger RNA (mRNA) expression were determined with SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis) and RT-PCR (real-time polymerase chain reaction), respectively; IGF-1 (insulin-like growth factor 1), MuRF-1 (muscle RING-finger protein-1), and MAFbx (muscle atrophy f-box) mRNA expression were determined with quantitative RT-PCR. Results: Following 6 weeks of exercise intervention, the single-legged hop test results improved significantly in the exercise-injured limb compared with baseline (P = .001). Quadriceps peak torque in the injured limb improved with similar gains in CSA compared with baseline (P = .001). However, this was not significantly increased compared with the control group. Quadriceps and vastus medialis CSA were also larger in the exercise group than in controls (P = .0024 and P = .015, respectively). The modified Cincinnati score was better in the exercise-injured limb compared with baseline. At 12 weeks postoperatively, the rate of decline in the single-legged hop test was reduced in the exercise group compared with controls (P = .001). Similar trends were not seen for quadriceps peak torque and CSA. The vastus medialis CSA had regressed to similar levels as the control group (P = .008). The modified Cincinnati score continued to increase in the exercise group compared with controls (P = .004). The expression of the hypertrophic IGF-1 gene was significantly increased after the exercise intervention (P = .028), with a decrease back to baseline 12 weeks postoperatively (P = .012). Atrophic MuRF-1 gene expression was decreased after intervention compared with baseline (P = .05) but increased again at 12 weeks postoperatively (P = .03). The MAFbx levels did not change significantly in either group and within each time point. On the mRNA level, there was a shift from MHC-IIx isoform to MHC-IIa after exercise, with significant changes compared with control preoperatively (P = .028). Protein testing was able to reproduce this increase for MHC-IIa isoform expression only. Conclusion: The 6-week progressive prehabilitation program for subjects undergoing ACLR led to improved knee function based on the single-legged hop test and self-reported assessment using the modified Cincinnati score. These effects were sustained at 12 weeks postoperatively. This study supports prehabilitation as a consideration for patients awaiting ACLR; however, further studies are warranted.

The validity of estimating triceps brachii volume from single MRI cross-sectional area before and after resistance training

The aim of this study was to determine whether triceps brachii muscle volume can be adequately estimated from a single anatomical cross-sectional area (ACSA) and can the same model be used for prediction after training. Thirty-five healthy male non-athletes (age 21.6 ± 2.5 years, body mass index 24.8 ± 3.5 kg · m−2) volunteered for this study. The volumes of the upper arm extensors were calculated from magnetic resonance imaging (MRI) sequence scans and regression models were developed, which were used to predict muscle volumes from single MRI cross-sectional scans taken at different points along the humerus length. The same procedure was repeated after 12 weeks of maximal resistance training of the elbow extensors. Correlation coefficients were calculated for Model A with CSAmax, humerus length (HL), and body mass index (r = 0.919), a model with CSA50% and HL (r = 0.922), and a model with CSA60% and HL (r = 0.920) (P < 0.001). The standard error of estimate for Model A, Model CSA50%, and Model CSA60% was 8.0%, 7.7%, and 7.8% respectively. Thesame prediction formula can be used for the left arm (r = 0.904). If a single ACSA is used for triceps brachii volume prediction, the best fit is with Model CSA60% and HL, both before and after training (r = 0.941). By introducing humerus length into the calculation, we simplify the procedure for volume measurement, since it can be obtained during MRI scanning.

Preoperative Magnetic Resonance Imaging Cross-Sectional Area for the Measurement of Hamstring Autograft Diameter for Reconstruction of the Adolescent Anterior Cruciate Ligament

We conducted this study to determine if preoperative magnetic resonance imaging (MRI) cross-sectional area measurements would correlate with intraoperative graft size in hamstring anterior cruciate ligament (ACL) reconstructions. We retrospectively reviewed ACL reconstructions performed by a single surgeon using a quadruple-looped hamstring allograft. Preoperative MRI axial images were used to determine the combined cross-sectional area of the semitendinosis and gracilis tendons. These cross-sectional areas were correlated to the intraoperative graft size. We found a strong correlation between the MRI cross-sectional areas and graft size. If the combined cross-sectional areas were >or=18 mm(2), there was an 88% probability of obtaining a graft of sufficient size at the time of surgery. We conclude that our technique is a reliable option to assist the surgeon with preoperative determination of graft size. This is valuable to the orthopaedist to more accurately discuss graft options with the patient and improve preoperative preparation with respect to graft choice. Level II, development of diagnostic criteria on the basis of consecutive patients with universally applied gold standard.

Serum Levels of Retinol-Binding Protein 4 and Adiponectin in Women with Polycystic Ovary Syndrome: Associations with Visceral Fat But No Evidence for Fat Mass-Independent Effects on Pathogenesis in This Condition

Insulin resistance, which associates with levels of retinol-binding protein 4 (RBP4) and adiponectin, is implicated in the development of polycystic ovary syndrome (PCOS). The objective of the study was to explore the potential contribution of RBP4 and adiponectin in the etiology of PCOS and their relationships with specific fat depot measurements. This was a cross-sectional study. Serum RBP4 and adiponectin levels were compared between 50 PCOS cases and 28 female controls (including 22 body mass index/fat mass-matched pairs) and correlated with specific fat depot (including visceral) axial magnetic resonance imaging cross-sectional area measurements. All subjects were of U.K. British/Irish origin. Serum levels of RBP4 (automated immunonephelometric assay) and adiponectin [immunoassay: total and high molecular weight (HMW)]. Data are reported as geometric mean (sd, range) and optionally adjusted for fat mass and age. Between the 50 PCOS cases and 28 controls, serum RBP4 levels were indistinguishable [39.0 microg/ml (31.0, 49.0) vs. 41.6 microg/ml (32.7, 52.9), respectively, unadjusted P = 0.24; adjusted P = 0.55]. Total (and HMW) adiponectin levels were lower in PCOS cases [total adiponectin 19.9 microg/ml (14.2, 27.8) vs. 25.8 microg/ml (17.7, 37.7), respectively, unadjusted P = 2.4 x 10(-3); adjusted P = 0.10]. For the paired-sample analyzes, there were no differences in RBP4 (P = 0.09), total adiponectin (P = 0.06), HMW adiponectin (P =0.19), or HMW to total adiponectin ratio (P = 0.98). In PCOS cases, L4-visceral fat area was associated positively with RBP4 (r(2) = 0.34, P = 0.01) and negatively with HMW to total adiponectin ratio (r(2) = -0.44, P = 1.3 x 10(-3)). Controls showed similar relationships. Although associated with visceral fat, serum RBP4 and adiponectin levels do not play important, fat-mass-independent primary roles in the development of PCOS.

The Effects of Semitendinosus and Gracilis Harvest in Anterior Cruciate Ligament Reconstruction

There is significant debate concerning the morbidity of hamstring harvest for use during anterior cruciate ligament (ACL) reconstruction. We hypothesized that harvest of the semitendinosus and gracilis tendons for ACL reconstruction would result in no measurable hamstring weakness, but that abnormalities of the semitendinosus and gracilis muscle would be observed on magnetic resonance imaging (MRI) scans. Case series. Nine patients undergoing ACL reconstruction with doubled semitendinosus and gracilis tendons had MRI cross-sectional area measurements of both limbs made from axial images and muscle contour was studied on coronal images at 3 and 12 months. The semitendinosus, semimembranosus, gracilis, sartorius, and biceps muscles were evaluated. Isokinetic testing was performed on the operative and nonoperative legs at 60 degrees and 180 degrees per second at 6 and 12 months postoperatively. The gracilis cross-sectional area at 1 year averaged 2 cm2 on the operative side and 3.7 cm2 on the contralateral side. The semitendinosus averaged 2.1 cm2 on the operative side and 6.6 cm2 on the contralateral side at 1 year. Both of these differences were statistically significant (P < .05). In most cases, the semitendinosus muscle was retracted. Distally, the gracilis and occasionally the semitendinosus were blending with the gastrocnemius or sartorial fascia. The gracilis and semitendinosus in 1 case extended to near the original attachment site. Hamstring strength testing revealed a 26% deficit on the operative side at 60 degrees/second at 6 months and 16% at 180 degrees/second. At 12 months the mean 60 degrees/second deficit was 21% and the deficit at 180 degrees/second was 13%. At 1 year, the semitendinosus and gracilis muscles showed significant and persistent atrophy on the operative side and frequent retraction of the semitendinosus muscle belly. There were also hamstring strength deficits persisting at 1 year after the use of the tendons for ACL reconstruction. Level IV.

Thigh muscle size and strength after anterior cruciate ligament reconstruction and rehabilitation.

It is the hypothesis of the senior author (GAA) that high circumference measurements are not an accurate reflection of thigh muscle cross-sectional area or muscle strength after standard rehabilitation following anterior cruciate ligament reconstruction. Likewise, normal quadriceps femoris strength is not achieved in these patients despite aggressive rehabilitation. The purpose of our study was to quantify thigh muscle size and strength and correlate thigh circumference, muscle cross-sectional area by magnetic resonance imaging (MRI), and isokinetic strength in our patients. Thirty-three patients with anterior cruciate ligament repair utilizing autografts of iliotibial band (N = 28), semitendinosus autograft (N = 3), and bone-patellar tendon-bone autograft (N = 2) were retrospectively evaluated 48.7 +/- 6.91 months after surgery. We compared involved operated extremities with uninjured, uninvolved contralateral extremities, measuring thigh circumference, isokinetic peak torque, and cross-sectional area by MRI. We found a significant 1.8% decrease in thigh circumference, a 10% decrease in average quadriceps torque, and a 8.6% decrease in quadriceps cross-sectional area by MRI in the involved extremities compared with the uninvolved extremities. A positive correlation between MRI cross-sectional area, quadriceps, and hamstring peak torque was recorded in involved and uninvolved extremities. A positive correlation between thigh circumference, quadriceps, and hamstring peak torque was found in uninvolved extremities but not in operated extremities. The authors concluded that thigh circumference underestimates atrophy and is not correlated with cross-sectional thigh muscle area by MRI or strength in operated extremities. Persistent quadriceps weakness and decreased cross-sectional area at 49 months postsurgery and rehabilitation continue to challenge our efforts. The pathophysiology of the decrease in thigh muscle size and quadriceps femoris strength is discussed.

Annual Meeting of the American Laryngological, Rhinological, and Otological Society

This meeting was held at Marriott's Desert Springs Hotel, Palm Desert, Calif, May 1 through 3, 1995. (2) Using magnetic resonance imaging cross-sectional area to calculate the volume of acoustic neuromas in patients with neurofibromatosis type 2, Mona Abaza, MD , and coauthors, San Antonio, Tex, studied the growth characteristics and associated audiologic parameters of these tumors. While the average growth rate of acoustic neuromas in patients with neurofibromatosis type 2 was 0.30 cm/y, the rate was significantly higher in older patients and in patients with spinal tumors. For these two groups, Dr Abaza recommends close follow-up with baseline magnetic resonance imaging and serial audiograms and aggressive treatment. (3) An exciting new computer system designed to quantitatively and objectively assess facial paralysis expresses facial surface deformation as a dimensional variable based on light reflectance changes. J. Gaily Neely, MD