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Objective Spigelian hernia is an uncommon congenital or acquired defect in the transversus abdominis aponeurosis with non-specific symptoms posing a diagnostic challenge. There is a paucity of radiology literature on imaging findings of Spigelian hernia. The objective of this study is to explore the role of MDCT in evaluating Spigelian hernia along with clinical and surgical implications. Materials and methods In this IRB approved, HIPAA compliant retrospective observational analysis MDCT imaging findings of 43 Spigelian hernias were evaluated by two fellowship-trained radiologists. Imaging features evaluated were: presence of Spigelian hernia, laterality, relation to “hernia belt” (between 0 and 6 cm cranial to an imaginary axial line between both anterior superior iliac spines), the hernia neck and sac sizes, hernia content, and other coexistent hernias (umbilical, incisional, inguinal). Patient's demographics (age, gender, BMI, conditions with increased intra-abdominal pressure) were also recorded for any correlation. Results 60% (26/43) of Spigelian hernias were located below the hernia belt while 33% (14/43) within the hernia belt and 7% (3/43) above the hernia belt. The most common subtype of Spigelian hernia encountered was interparietal (84%). The mean hernia neck diameter was 3.4 cm, mean hernia sac volume was 329 cc. Hernia content included: fat (43/43) bowel (23/43), fluid (3/43). 3 patients had no clinical history provided, the remaining 37 patients' clinical presentation was asymptomatic in 73% (27/37), acute abdominal pain in 5% (2/37) and chronic abdominal pain in 22% (8/37). None of the hernia were incarcerated and none of the patients underwent emergent surgery. No significant correlation was noted between Spigelian hernia and causes of increased intra-abdominal pressure. 90% of our patients had other abdominal hernias. 30.9 was the mean BMI (20.8–69.1). Conclusion Most of the Spigelian hernia occurred below the traditionally described hernia belt and the majority are of interparietal subtype that can be best diagnosed with MDCT in contrast to physical examination.

Rationale and Objectives Publishing is critical for academic medicine career advancement. Rejection of manuscripts can be demoralizing. Obstacles faced by clinical faculty may include lack of time, confidence, and optimal writing practices. This study describes the development and evaluation of a peer-writing group, informed by theory and research on faculty development and writing. Materials and Methods Five clinical-track radiology faculty members formed a “Writers' Circle” to promote scholarly productivity and reflection on writing practices. Members decided to work with previously rejected manuscripts. After members' initial meeting, interactions were informal, face to face during clinical work, and online. After the first 6 months, an anonymous survey asked members about the status of articles and evaluations of the writing group. Results Ten previously rejected articles, at least one from each member, were submitted to the Circle. In 6 months, four manuscripts were accepted for publication, five were in active revision, and one was withdrawn. All participants (100%) characterized the program as worth their time, increasing their motivation to write, their opportunities to support scholarly productivity of colleagues, and their confidence in generating scholarship. Conclusions Peer-support writing groups can facilitate the pooling of expertise and the exchange of recommended writing practices. Our peer-support group increased scholarly productivity and provided a collegial approach to academic writing.

Aims: The purpose of this study was to evaluate the ability of ultrasound in detecting subscapularis tendon pathology with operative correlation. Methodology: A retrospective study was conducted on 86 patients who had shoulder ultrasound prior to surgical repair from January 2006 to August 2008. All sonographic examinations and surgical reports were reviewed. Sonographic evaluation of subscapularis tendon, including normal, tendinosis, partial thickness tear, full thickness tear, and complete tear were correlated to operative reports. Results: Of the 86 patients, 19 patients had surgically proven abnormal subscapularis tendons. There was 100% ultrasound concordance in tendinosis (n = 1), 100 % ultrasound concordance in partial thickness tears (n =3), 88 % ultrasound concordance in full thickness tears (n = 8), 57 % ultrasound concordance in complete tears (n = 7). Overall, there was 79% ultrasound concordance

MR imaging appearances of different types of reconstructive muscle flaps following reconstructive surgery of the lower extremity with associated post-surgical changes due to altered anatomy, radiation, and potential complications, can be challenging. A multidisciplinary therapeutic approach to tumors allows for limb salvage therapy in a majority of the patients. Decision-making for specific types of soft tissue reconstruction is based on the body region affected, as well as the size and complexity of the defect. Hematomas and infections are early complications that can jeopardize flap viability. The local recurrence of a tumor within six months after a complete resection with confirmed tumor-free margins and adjuvant radiation therapy is rare. Identification of a new lesion similar to the initial tumor favors a finding of tumor recurrence.

The purpose of this study was to establish normative data for the CT appearance of inguinal lymph nodes. After Institutional Review Board approval, search of the radiology information system identified 500 consecutive CT examinations of the pelvis. Patients were included if no lower extremity or perineum pathology, or history of malignancy at the time of CT examination, and a clinical note documenting no tumor at least 2 years after the CT. The final study group was 77 patients. CT examinations were retrospectively reviewed and bilateral inguinal lymph nodes were characterized by size (short axis and largest size in general), number, and presence of fat attenuation. The mean short-axis inguinal lymph node size was 5.4 mm (range 2.1–13.6 mm), measured at 8.8 mm two standard deviations above the mean. The mean number of superficial and deep inguinal lymph nodes was 10.7 (range 3–18) and 1.2 per patient (range 1–2), respectively. Superficial and deep inguinal nodes showed internal fat attenuation in 85 and 78 % of nodes, and were oval in shape in 95 and 78 %, respectively. Inguinal lymph nodes in asymptomatic patients have a mean short axis of 5.4 mm, a short axis of 8.8 mm at two standard deviations above the mean, and are multiple and symmetric in size and number (4–20 per patient). Normal inguinal lymph nodes were commonly oval in shape and contained fat, although such findings may be absent in smaller lymph nodes.

Objectives The purpose of this study was to determine whether any sonographic features of jumper's knee can predict the outcome after sonographically guided percutaneous patellar tendon fenestration. Methods Patients were identified between July 2001 and March 2009 who had clinical and sonographic findings of jumper's knee, who had failed conservative treatment, and who had sonographically guided percutaneous fenestration of the patellar tendon. Pain levels were assessed before and 4 weeks after fenestration. Sonograms were retrospectively characterized with regard to echogenicity, size, definition, location, calcification, and hyperemia of the abnormal patellar tendon region. Sonographic findings before fenestration were correlated with clinical outcomes. Results A total of 45 patellar tendons (32 consecutive patients) were included in the study. The average prefenestration functional pain score was 3.6 (range, 2-5), and the average postprocedure functional pain score after 4 weeks was 1.4 (range, 0-5). The preprocedure sonographic finding that correlated with an improved clinical outcome after tendon fenestration was the presence of a well-defined tendon abnormality. No other sonographic findings were associated with the clinical outcome. After fenestration, 76% (34 of 45) showed clinical improvement; 24% (11 of 45) showed no change; and 0% (0 of 45) had worse symptoms at 4 weeks. Conclusions The presence of a well-defined area of tendinosis on sonography was associated with clinical improvement after percutaneous sonographically guided fenestration of the patellar tendon. All tendons either improved (76%) or showed no change (24%) in the functional pain score at 4 weeks after fenestration.

The rotator interval is an anatomically defined triangular area located between the coracoid process, the superior aspect of the subscapularis, and the anterior aspect of the supraspinatus. It is widely accepted that the rotator interval structures fulfill a role in biomechanics and pathology of the glenohumeral joint and long head biceps tendon. However, there is ongoing debate regarding the biomechanical details and the indications for treatment. A better understanding of rotator interval anatomy and function will lead to improved treatment of rotator interval abnormalities, and guide the indications for imaging and surgical intervention.

Objectives Implanted mesh for inguinal hernia repair is often difficult to visualize with gray scale sonography and may present without the knowledge of the sonographer. We sought to evaluate the utility of the twinkling artifact produced by inguinal mesh to assist in mesh identification. Methods Two reviewers evaluated focused sonographic examinations of 44 inguinal regions, 24 of which had implanted inguinal mesh. The sonographic examinations consisted of static gray scale and color Doppler images with both linear and curvilinear array transducers. The presence of the twinkling artifact and visibility of the mesh were graded on a 4-point visibility scale. Results Inguinal mesh was not easily identified on gray scale imaging using either the curvilinear array (P = .5) or linear array (P = .5) transducer. The mesh was definitely seen in 3 of 24 inguinal regions using the linear array transducer and 2 of 24 inguinal regions using the curvilinear array transducer. In 79% of inguinal regions with mesh, the twinkling artifact was produced with the curvilinear array transducer only. The artifact was not elicited when using the linear array transducer. With the use of the curvilinear array transducer and the presence of the twinkling artifact, there was a significant chance of correctly identifying the presence of mesh (P Conclusions Standard gray scale imaging alone is not reliable when identifying inguinal mesh. The twinkling artifact was present in 79% of inguinal regions with mesh when evaluated with a low-frequency curvilinear array transducer.

Bisphosphonate-related osteonecrosis of the jaw (ONJ) is characterized by nonhealing exposed bone in the maxillofacial region in patients who have undergone bisphosphonate treatment. The underlying etiology is unclear and may be multifactorial. The diagnosis is primarily clinical. Diagnostic tissue sampling may exacerbate the process and is typically avoided, necessitating other diagnostic approaches. The appearance of ONJ at diagnostic imaging is variable and includes sclerotic, lytic, or mixed lesions with possible periosteal reaction, pathologic fractures, and extension to soft tissues. There is a spectrum of signal intensity changes on T1- and T2-weighted magnetic resonance (MR) images with variable enhancement, findings that may correspond to the clinical and histopathologic stage of the process. Bone scintigraphy is sensitive with increased uptake in the area of the lesion. Although the imaging findings are nonspecific, there appears to be a role for imaging in the management of ONJ. Radiography is relatively insensitive but typically employed as the first line of radiologic investigation. Computed tomography and MR imaging are more precise in demonstrating the extent of the lesion. A number of imaging modalities have revealed lesions that may be associated with bisphosphonate exposure in asymptomatic individuals or in the context of nonspecific symptoms. The risk of these lesions advancing to overt clinical disease is unknown at this time. The radiologist should be aware of ONJ and include it in the differential diagnosis when evaluating patients with a history of bisphosphonate therapy without jaw irradiation, so as to avoid potentially harmful biopsies.

The aim of this study was to evaluate the magnetic resonance imaging (MRI) interpretation proficiency of musculoskeletal fellows in training.Between July 2003 and June 2007, 14 musculoskeletal fellows were independently tested with 20 MRI studies of the knee and shoulder at four separate time points during their fellowship years. Trends in true-positive and false-positive interpretation results were evaluated. Fellows who completed their residencies at the fellowship institution (internal fellows) were compared with those from other residencies (external fellows).There was a significant improvement in proficiency between the initial and final (9-month) evaluations (P.0001). At the initial evaluation, there was a mean of 52.8% (41.7 of 79) true-positive results (range, 32-51); at 9 months, there was a mean of 71.0% (56.1 of 79; range, 40-72). The number of false-positive results also declined during this time period from a mean of 8.1 (range, 2-13) at initial evaluation to 4.7 (range, 2-8) at 9 months (P.001). External fellows had more incorrect diagnoses initially but showed greater improvement than internal fellows at 9 months.Fellows continued to improve their MRI interpretation skills throughout the first 9 months of their fellowships. External fellows were slightly less proficient at the start of their fellowships but slightly more proficient at 9 months compared to internal fellows.

We report a new lateral approach for ultrasound visualization of the distal biceps tendon. A cadaver specimen was dissected to study distal biceps anatomy relevant to this approach. Sonograms obtained in volunteers and patients are provided to illustrate this alternative method.

Objective The purposes of this study were (1) to review the sonographic in vitro and in vivo appearances of mesh for surgical repair of abdominal wall hernias, (2) to describe sonographic techniques and discuss the limitations of sonography in evaluation of mesh hernia repair, and (3) to illustrate common complications after mesh repair shown with sonography. Methods We identified interesting cases from the musculoskeletal sonographic database as well as from the teaching files of the authors, with surgical or other cross-sectional imaging corroboration. Results A compilation of the sonographic appearances of mesh used for anterior abdominal wall and inguinal hernia repair and complications diagnosable by sonography is presented. Conclusions Sonography can be effective for evaluation of mesh and complications after mesh repair of anterior abdominal wall and inguinal hernias.

Summary Objective To elucidate the role of body mass index (BMI) and knee osteoarthritis (OAK) by evaluating measures of body composition including fat mass and skeletal muscle mass (SMM). Methods Data are from 541 women enrolled in the Michigan Bone Health Study, a longitudinal, population-based study. At visits in 1998 and 2002, radiographs were taken of both knees and were evaluated for the presence of OAK (≥2 on the Kellgren–Lawrence (K–L) scale). Joint space width (JSW) was measured with electronic calipers. Fat mass and SMM were determined using bioelectrical impedance analysis. Results In 2002, the prevalence of OAK was 11% in this population of women whose mean age was 47 years. Fat mass, lean mass, SMM, waist circumference and BMI were greater in women with OAK compared to those without OAK. In multiple variable analyses adjusted for age, fat mass and SMM explained OAK prevalence and increasing OAK severity better than models with BMI; further SMM explained more variation than did fat mass. SMM was positively associated with level of left and right medial JSW while there was no consistent association of JSW and BMI or fat mass. Conclusion Fat mass and SMM were associated with K–L OAK score and the amount of joint space, with more variation explained by SMM. SMM was highly associated with JSW. Therefore, though obesity, frequently characterized by BMI, is a frequently reported risk factor for OAK, this mis-attribution may mean that interventions that focus on weight loss as treatment for osteoarthritis should be aware that this may negatively impact muscle mass.

This article evaluates the utility of performing a focused musculoskeletal sonography examination on the basis of patients' presenting complaints.Six hundred two patients evaluated over 6 months were scanned using a routine protocol. At the completion of the routine examination, each patient was asked to indicate a focal point of discomfort and, if present, was rescanned over the area of discomfort. Patients were classified in one of five categories depending on whether there was a focal point of discomfort and the presence or absence of an underlying sonographic abnormality.Eighty-three percent of the 602 patients had a sonographically detectable abnormality, 2.2% of whom had an abnormality not detectable by routine protocol-based scanning. The more peripheral the body part, the more likely that abnormalities detected by sonography correlated with focal symptoms: 81% in the wrist and hand and 73% in the ankle and foot, compared with the more central body parts of 15% in the shoulder and 31% in the hip. Chi-square analysis showed a significant association between the body part scanned and a detectable abnormality (p0.0001).Although a focused examination of the distal extremities correlated with an abnormality in most cases, a protocol-based approach ensured identifying 97.4% of the symptomatic abnormalities. The addition of a focused examination to an examination by protocol further increased the identification of abnormalities.

Inguinal hernias are a common cause of groin discomfort, and when small they may be difficult to diagnose clinically. Sonography is a useful imaging modality aiding in the diagnosis of inguinal hernias and their complications both before and following surgery. Inguinal anatomy is discussed briefly, but this article emphasizes scanning technique and pitfalls that may be encountered when using sonography to diagnose small and often clinically occult inguinal hernias.

We have noted apparent far lateral meniscal attachment of the meniscofemoral ligament (MFL) with an anterior cruciate ligament (ACL) tear. This study evaluates MFL attachment and association with posterior horn lateral meniscus (PHLM) tear. Nine months of knee arthroscopy reports were reviewed to classify the PHLM and ACL as torn or normal. After excluding those with prior knee surgery, MR images were reviewed by two radiologists to determine the number of images lateral to PCL, which showed the ligaments of Humphrey and Wrisberg visible as structures separate from the PHLM. Any patient with abnormal PHLM surface signal not continuous with the MFL was excluded. MRI findings were compared with arthroscopy using Student’s t test and Fisher’s exact test. Of the 54 participants, 5 had PHLM tears and 49 were normal. Twenty-one had ACL tears; all those with an PHLM tear had an ACL tear. The ligament of Humphrey inserted on average 0.9 consecutive images lateral to the PCL without an PHLM tear and 4.7 with an PHLM tear; the ligament of Wrisberg inserted on average 3.0 consecutive images without an PHLM tear and 4.5 with an PHLM tear (slice thickness/gap = 3 mm/0.5 mm). There was a significant association between PHLM tear and number of images (p = 0.0028), and between ACL tear and this type of PHLM tear (p = 0.0064). Apparent far lateral meniscal extension of a meniscofemoral ligament (greater than or equal to four images lateral to the PCL) should be considered as a possible PHLM tear, especially in the setting of an ACL tear.

OBJECTIVE. We have found in our practice that the normal extensor retinaculum of the wrist may appear hypoechoic on sonography and, because it is closely applied to the extensor tendons, may simulate tenosynovitis. This study prospectively evaluates the extensor retinaculum in 50 healthy adult volunteers, characterizing its sonographic appearance.CONCLUSION. The extensor retinaculum has a characteristic appearance on sonography. A hypoechoic appearance from anisotropy should not be confused with tenosynovitis.

OBJECTIVES The purpose of this article is to evaluate the diagnostic accuracy of sonography in clinically occult femoral hernias and to describe our sonographic technique. METHODS The clinical and imaging data for 93 outpatients referred by general surgeons, all of whom underwent sonographic evaluation and surgery, were reviewed retrospectively. Of these, 55 patients who underwent surgical exploration for groin hernias within 3 months of sonography and met all inclusion criteria were included in the study. The sonographic technique involves using the pubic tubercle as an osseous landmark to identify and appropriately visualize the femoral canal. The Valsalva maneuver is then used to differentiate the movement of normal fat (a potential pitfall) from true herniation in the femoral canal. Surgical findings were used as the reference standard by which sonographic results were judged. Two-by-two contingency tables were used to calculate the sensitivity, specificity, positive predictive value, and negative predictive value. RESULTS In these 55 patients, surgery revealed 15 femoral hernias. Eight femoral hernias occurred in women, and 7 occurred in men. For diagnosing femoral hernias, sonography demonstrated sensitivity of 80%, specificity of 88%, a positive predictive value of 71%, and a negative predictive value of 92%. True-positive cases of femoral hernias have a sonographic appearance of a hypoechoic sac with speckled internal echoes. When examining during the Valsalva maneuver, a femoral hernia passes deep to the inguinal ligament, expands the femoral canal, displacing the normal canal fat, and effaces the femoral vein. CONCLUSIONS Sonography can exclude femoral hernias with high confidence in light of its exceptional negative predictive value. With attention to technique and imaging criteria, the diagnostic accuracy of sonography can be enhanced.

OBJECTIVE. Accurate characterization of acetabular fractures can be difficult because of the complex acetabular anatomy and the many fracture patterns. In this article, the five most common acetabular fractures are reviewed: both-column, T-shaped, transverse, transverse with posterior wall, and isolated posterior wall. Fracture patterns on radiography are correlated with CT, including multiplanar reconstruction and 3D surface rendering.CONCLUSION. In the evaluation of the five most common acetabular fractures, assessment of the obturator ring, followed by the iliopectineal and ilioischial lines and iliac wing, for fracture allows accurate classification. CT is helpful in understanding the various fracture patterns.

Photoacoustic tomography (PAT), a nonionizing, noninvasive, laser-based technology was adapted to joint imaging for the first time. Pulsed laser light in the near-infrared region was directed toward a joint with resultant ultrasonic signals recorded and used to reconstruct images that present the optical properties in subsurface joint tissues. The feasibility of this joint imaging system was validated on a Sprague Dawley rat tail model and verified through comparison with histology. With sufficient penetration depth, PAT realized tomographic imaging of a joint as a whole organ noninvasively. Based on the optical contrast, various intra- and extra-articular tissues, including skin, fat, muscle, blood vessels, synovium and bone, were presented successfully in images with satisfactory spatial resolution that was primarily limited by the bandwidth of detected photoacoustic signals rather than optical diffusion as occurs in traditional optical imaging. PAT, with its intrinsic advantages, may provide a unique opportunity to enable the early diagnosis of inflammatory joint disorders, e.g., rheumatoid arthritis, and to monitor therapeutic outcomes with high sensitivity and accuracy.

OBJECTIVE. The purpose of this article is to describe the anatomy of the inguinal region in a way that is useful for sonographic diagnosis of inguinal region hernias, and to illustrate the sonographic appearance of this anatomy. We show sonographic techniques for evaluating inguinal, femoral, and spigelian hernias and include surgically proven examples.CONCLUSION. Understanding healthy inguinal anatomy is essential for diagnosing inguinal region hernias. Sonography can diagnose and differentiate between various inguinal region hernias.

To prospectively compare magnetic resonance (MR) imaging-defined abnormalities of osteoarthritis (OA) of the knee with radiographic severity measurements of OA of the knee and self-reported pain.This study was approved by the institutional review board of University of Michigan. Informed consent was obtained for this HIPAA-compliant study. Knee MR imaging was performed in 117 women (mean age, 46 years; range, 32-56 years) from a community-based arthritis study (n = 1053) with 30 women in each of four categories: (a) no pain and no OA of the knee, (b) no pain and OA of the knee, (c) pain and no OA of the knee, and (d) pain and OA of the knee. OA of the knee was defined from radiographs. Two hundred thirty-two eligible knees had Kellgren-Lawrence scores for OA of the knee as follows: grade 0, 115 (49.6%); grade 1, 33 (14.2%); grade 2, 66 (28.4%); grade 3, 17 (7.3%); and grade 4, one (0.4%). MR images were assessed for location and severity of defects of cartilage, bone marrow edema (BME), osteophytes, subchondral cysts, sclerosis, meniscal and/or ligamentous tears, joint effusion, synovial cysts, and synovitis. MR imaging findings were compared with radiographic severity of OA of the knee (Kellgren-Lawrence scale) and self-reported pain with analysis of variance, t tests, and contingency table analyses.Defects of cartilage (higher than grade IIA) were found in 75% of knees; BME was found in 57% of knees (1 cm, 41%;1 cm, 16%). Large BME lesions were common in the pain and OA of the knee group (P = .001); this group was significantly more likely to have defects of cartilage (P = .001); meniscal tears (P = .001); and osteophytes, subchondral cysts, sclerosis, joint effusion, and synovitis (P.001). Defects of cartilage, osteophytes, sclerosis, meniscal or ligamentous tears, joint effusion, and synovitis were strongly related to increasing Kellgren-Lawrence grade (P.001).In middle-aged women, there were significant associations between pain, radiographic severity of OA of the knee, and seven MR imaging-identified parameters.

Rationale and objectives One mission of an academic radiology department is to teach. The greatest teaching effort is directed at radiology residents. As clinical work demands increase, informal, non−revenue-generating, teaching may suffer. We sought to determine the economic consequences of teaching. Materials and methods With the use of a picture archiving and communications system, 6 radiology faculty members independently interpreted and dictated digitally acquired bone and chest radiographs for 1 hour alone and again 10−12 weeks later with a first-year resident. During the second session, the quality of teaching was graded by independent observers. The number of cases, relative value units (RVUs), and reimbursement for each session were calculated. Results The difference in number of cases dictated working alone (mean, 44.7) and with a first-year resident (mean, 23.5) was significant ( P = 0.007). The difference between RVUs generated by faculty alone (mean, 9.0) and with a resident (mean, 4.5) also was significant ( P = 0.006), and the difference in dollars billed when working alone (mean, $1558.45) and with a resident (mean, $777.65) was significant ( P = 0.007). As teaching quality increased, the number of cases interpreted, dollars billed, and RVUs trended lower. Conclusion Informal resident teaching significantly reduces clinical throughput, reducing examination volume, RVUs, and dollars billed by approximately half.

To understand a linear artifact that projects deep to reflective structures that move rapidly while using tissue harmonic imaging with pulse inversion (PI) sonography. We hypothesize that this artifact is due to a cancellation error between firings in PI imaging, and it is, therefore, similar in generation to the twinkling artifact in color Doppler sonography. This artifact could be studied with the use of surfaces of different roughness to represent different rates of motion, in which roughness corresponds to spatial fluctuations in surface height. Given very slight variations in beam focusing as occurs with sonographic imaging arrays, these spatial fluctuations translate into temporal fluctuations in the received signal as would occur with tissue motion.We scanned 4 different sandpaper grits and a smooth surface through a water path using fundamental and PI mode, 1- and 2-pulse techniques, respectively. The sandpaper and the smooth surface were scanned through a water path at mechanical indices of 0.1 to 0.7. Four independent images were subtracted pairwise to remove nonfluctuating signals. These noise pixels were counted and analyzed.Analysis of variance showed that the noise generated behind the different surfaces was highly significantly different. Two-tailed t tests generally showed significant differences in the quantity of noise between fundamental and harmonic imaging behind the roughest 3 grades of sandpaper. A multiple regression model showed significantly greater slopes for harmonic imaging for all grades of sandpaper and the smooth surface.The noise and, by extension, the linear streak artifact in musculoskeletal imaging are dependent on the mechanical index and are functions of sandpaper roughness. This would be equivalent to a subtraction error between 2 firings due to soft tissue motion, and the artifact may be a way to identify rapid soft tissue motion in PI images.

Six patients were retrospectively identified as having undergone lateral ligament reconstruction surgery. The surgical procedures were categorized into four groups: direct lateral ligament repair, peroneus brevis tendon rerouting, peroneus brevis tendon loop, and peroneus brevis tendon split and rerouting. At radiography and magnetic resonance (MR) imaging, the presence of one or more suture anchors in the region of the anterior talofibular ligament indicates direct ligament repair, whereas a fibular tunnel indicates peroneus brevis tendon rerouting or loop. Both ultrasonography (US) and MR imaging demonstrate rerouted tendons as part of lateral ankle reconstruction; however, MR imaging can also depict the rerouted tendon within an osseous tunnel if present, especially if T1-weighted sequences are used. Artifact from suture material may obscure the tendon at MR imaging but not at US. With both modalities, the integrity of the rerouted peroneus brevis tendon is best evaluated by following the tendon proximally from its distal attachment site, which typically remains unchanged. The rerouted tendon or portion of the tendon can then be traced proximally to its reattachment site. Familiarity with the surgical procedures most commonly used for lateral ankle ligament reconstruction, and with the imaging features of these procedures, is essential for avoiding diagnostic pitfalls and ensuring accurate assessment of the ligament reconstruction.

Obese individuals have slowed conduction in the median nerve across the wrist, but the mechanism for this is not established. This case-control study of 27 obese subjects and 16 thin subjects was designed to test the hypothesis that obese individuals have higher carpal canal pressures and more median nerve swelling than thin individuals. All subjects were asymptomatic for hand symptoms, and had measurements of median and ulnar sensory nerve conduction in the nondominant hand, ultrasound measurement of the median nerve cross-sectional area proximal to the carpal canal, and carpal canal pressure measurement. There was no difference in age or gender ratio between the obese and thin groups. The median nerve cross-sectional area was equal in the obese and thin groups (9.3 mm2 vs. 9.4 mm2), as was the carpal canal pressure (16.2 mmHg vs. 15.5 mmHg, respectively). There was a strong correlation between median nerve conduction slowing across the wrist and median nerve cross-sectional area at the wrist (r = 0.55, P = 0.002). Obesity does not influence carpal canal pressure or the size of the median nerve at the wrist. However, there is a strong association between slowed median nerve conduction and increased nerve size which suggests endoneurial edema as a metabolic mechanism; the conduction slowing does not appear to be related to mechanical stress. Muscle Nerve 30: 481–485 2004

Objective With the use of surgical findings as the reference standard, the purpose of this study was to describe the sonographic findings of partial-thickness and complete tears of the quadriceps tendon and to determine whether sonography can potentially aid diagnosis. Methods Three hundred eighty-nine consecutive sonographic reports (January 1996 to April 2001) of the knee/quadriceps tendon were reviewed retrospectively and assessed for subsequent surgery on the quadriceps tendon. Seven cases were thus identified. Findings at surgery (complete versus partial tears) were compared with the original sonography reports. Results All 4 partial tears and 1 of 2 complete tears were diagnosed correctly on the basis of sonography. One complete tear was described as a partial tear on the basis of sonography. In a seventh case, complete disruption of the extensor mechanism with osseous avulsion of the superior pole of the patella was identified correctly. Dynamic scanning was essential in diagnosing a partial quadriceps tendon tear in 1 case. Conclusions Sonography, including the use of dynamic evaluation, was helpful in the diagnosis of partial-thickness tears of the quadriceps tendon and may aid in differentiation of such cases from complete quadriceps tendon tears, particularly in the acute setting. The presence of scar tissue in the setting of chronic injury may represent a potential pit-fall in the assessment of partial versus complete quadriceps tears. Further study is needed to define the accuracy of sonography for detecting quadriceps tendon tears.

The object of this study was to determine the effectiveness of sonography in the detection of hip joint effusions in both native and postoperative adult hips using arthrocentesis as a gold standard.Twenty-one consecutive patients with clinical suspicion of hip joint effusion were examined on sonography by one of five musculoskeletal radiologists with experience in musculoskeletal sonography. All 21 patients underwent diagnostic arthrocentesis (fluoroscopic in 16, sonographic in five) to confirm the presence or absence of joint effusion. A retrospective analysis of the sonograms was made to assess the size of the distention of the anterior joint recess (anteroposterior dimension) and the echogenicity (anechoic or other relative to muscle), and correlation was made to the presence or absence of joint effusion.Joint effusion was seen on diagnostic arthrocentesis in 10 (48%) of the 21 patients. Seven of the 21 patients had native hips and 14 had prior hip surgery. Retrospectively, no significant difference was found with regard to the size of the anterior recess distention (p = 0.34) or echogenicity (p = 0.2) when comparing the patients with and without joint effusion.Anterior recess distention and echogenicity could not reliably be used as an indicator of adult hip joint effusion, either in native or postoperative hips. Diagnostic arthrocentesis was necessary to establish or exclude the presence of hip joint effusion.

We present a case of traumatic bamboo foreign body penetration through the posterior thigh extending cephalad into the pelvis sustained during skiing. The unsuspected bamboo foreign body was missed prospectively on the initial portable trauma radiograph of the pelvis, but was retrospectively quite apparent as a linear 12 x 2-cm radiolucent region overlying the left pelvis and hip region. On CT examination, the bamboo stick appeared as a round cylindrical air-filled structure of high density compared to soft tissue - the typical appearance of bamboo. Bamboo foreign bodies can be recognized radiographically by this typical appearance, since it is one of the few wood products that causes high attenuation relative to soft tissue on CT.

The objective of our study was to sonographically characterize the dorsal aspect of the scapholunate ligament in cadaveric wrists using arthrography, MR arthrography, and anatomic correlation as the gold standard.The dorsal aspect of the scapholunate ligament in four cadaveric wrists was evaluated on sonography without knowledge of the findings from standard arthrography, MR arthrography, and anatomic sectioning. The sonographic findings were compared with the findings from other modalities. The criteria for an abnormal scapholunate ligament included an abnormal contrast communication between the radiocarpal and midcarpal joints on arthrography and a discontinuity of the dorsal aspect of the scapholunate ligament that was documented both on MR arthrography and at anatomic sectioning.Arthrography, MR arthrography, and anatomic sectioning showed the dorsal aspect of the scapholunate ligament to be normal in one specimen and abnormal in three specimens. On sonography, the normal scapholunate ligament was hyperechoic between the scaphoid and lunate bones. In the three cases of abnormality, a normal scapholunate ligament was not visualized, and an abnormal hypoechogenicity was present.The dorsal aspect of the scapholunate ligament can be depicted on sonography; abnormality is present in patients in whom the normally hyperechoic fibrillar ligament is hypoechoic or absent.

Occasionally patients who undergo magnetic resonance imaging for presumed pelvic disease demonstrate unexpected musculoskeletal imaging findings in the imaged field. Such incidental findings can be challenging to the abdominal radiologist, who may not be familiar with their appearance or know the appropriate diagnostic considerations. Findings can include both normal and abnormal bone marrow, osseous abnormalities such as Paget’s disease, avascular necrosis, osteomyelitis, stress and insufficiency fractures, and athletic pubalgia, benign neoplasms such as enchondroma and bone island, malignant processes such as metastasis and chondrosarcoma, soft tissue processes such as abscess, nerve-related tumors, and chordoma, joint- and bursal-related processes such as sacroiliitis, iliopsoas bursitis, greater trochanteric pain syndrome, and labral tears, and iatrogenic processes such as bone graft or bone biopsy. Though not all-encompassing, this essay will help abdominal radiologists to identify and describe this variety of pelvic musculoskeletal conditions, understand key radiologic findings, and synthesize a differential diagnosis when appropriate.

Osteoarthritis (OA) has been characterized as a slowly evolving degenerative disease affecting cartilage and bone, with a multifactorial etiology that may differ depending on the joint site. Because OA has been considered a disease of the elderly, few population-based studies have examined its frequency and characteristics in persons under the age of 45. Objective In this cross-sectional study, we examined X-rays of both knees and the dominant hand in a population of younger black and white pre- and perimenopausal women in southeastern Michigan ( N =1053) for evidence of osteoarthritis, and reported these outcomes according to the risk factors of age, body size, injury, and smoking behavior. Design Sixteen joints of the dominant hand as well as both knee joints (weight bearing) were evaluated using the Kellgren and Lawrence Atlas of Standard Radiographs of Arthritis. Results By age 40, radiographically-defined osteoarthritis emerges in both the hands and knees. These age characteristics are observed in both black and white women, however prevalence of knee OA was higher in black females (23.1%) compared with white females (8.5%), and although prevalence of hand OA was more comparable between black (25.5%) and white females (19.2%), the joint sites affected differed. The major risk factors reported in studies of older populations are present in this younger population where OA is newly emerging. Conclusions This study provides strong evidence that primary prevention of OA must be implemented in young adulthood to curtail the emergence of radiographically-defined OA at the mid-life.

Ventilation/perfusion scans with single-photon emission tomography (SPET) were reviewed to determine their usefulness in the evaluation of lung volume reduction surgery (LVRS) candidates, and as a predictor of outcome after surgery. Fifty consecutive planar ventilation (99mTc-DTPA aerosol) and perfusion (99mTc-MAA) scans with perfusion SPET of patients evaluated for LVRS were retrospectively reviewed. Technical quality and the severity and extent of radiotracer defects in the upper and lower halves of the lungs were scored from visual inspection of planar scans and SPET data separately. An emphysema index (EI) (extent x severity) for the upper and lower halves of the lung, and an EI ratio for upper to lower lung were calculated for both planar and SPET scans. The ratios were compared with post-LVRS outcomes, 3, 6 and 12 months after surgery. All perfusion and SPET images were technically adequate. Forty-six percent of ventilation scans were not technically adequate due to central airway tracer deposition. Severity, extent, EI scores and EI ratios between perfusion and SPET were in good agreement (r = 0.52-0.68). The mean perfusion EI ratio was significantly different between the 30 patients undergoing biapical LVRS and the 17 patients excluded from LVRS (3.3+/-1.8 versus 1.2+/-0.7; P0.0001), in keeping with the anatomic distribution of emphysema by which patients were selected for surgery by computed tomography (CT). The perfusion EI ratio correlated moderately with the change in FEV1 at 3 months (r = 0.37, P = 0.04), 6 months (r = 0.36, P = 0.05), and 12 months (r = 0.42, P = 0.03), and the transition dyspnea index at 6 months (r = 0.48, P = 0.014) after LVRS. It is concluded that patients selected to undergo LVRS have more severe and extensive apical perfusion deficits than patients not selected for LVRS, based on CT determination. SPET after aerosol V/Q imaging does not add significantly to planar perfusion scans. Aerosol DTPA ventilation scans are not consistently useful. Perfusion lung scanning may be useful in selecting patients with successful outcomes after LVRS.

Objective To determine whether Caucasian women ages 28–48 years with newly defined osteoarthritis (OA) would have greater bone mineral density (BMD) and less bone turnover over time than would women without OA. Methods Data were derived from the longitudinal Michigan Bone Health Study. Period prevalence and 3-year incidence of OA were based on radiographs of the dominant hand and both knees, scored with the Kellgren/Lawrence (K/L) scale. OA scores were related to BMD, which was measured by dual-energy x-ray absorptiometry, and to serum osteocalcin levels, which were measured by radioimmunoassay. Results The period prevalence of OA (K/L grade ≥2 in the knees or the dominant hand) was 15.3% (92 of 601), with 8.7% for the knees and 6.7% for the hand. The 3-year incidence of knee OA was 1.9% (9 of 482) and of hand OA was 3.3% (16 of 482). Women with incident knee OA had greater average BMD (z-scores 0.3–0.8 higher for the 3 BMD sites) than women without knee OA (P 60%; P = 0.02) or knee OA (20%; P not significant). The average change in absolute serum osteocalcin levels was not as great in women with incident hand OA or knee OA as in women without OA (P < 0.02 and P < 0.05, respectively). Conclusion Women with radiographically defined knee OA have greater BMD than do women without knee OA and are less likely to lose that higher level of BMD. There was less bone turnover among women with hand OA and/or knee OA. These findings suggest that bone-forming cells might show a differential response in OA of the hand and knee, and may suggest a different pathogenesis of hand OA and knee OA.

An arterioarticular fistula is an unusual complication of knee arthrocentesis. We describe the sonographic findings immediately following a failed clinical attempt at knee arthrocentesis that resulted in an arterioarticular fistula. Spectral Doppler analysis confirmed the jet of blood into the hemarthrosis. Knowledge of anatomy and application of standard technique is necessary to minimize the complications of arthrocentesis.

The purpose of our study was to determine if three-level thin-section CT depicts idiopathic pulmonary fibrosis (IPF) pathology as accurately as CT obtained at 10-mm increments throughout the entire lungs.Thin-section (1.0- to 1.5-mm) images at 10-mm increments were obtained and scored prospectively in 25 consecutive patients with newly diagnosed IPF who were participating in a Special Center of Research grant for interstitial lung disease. Each patient's lobe was scored by four thoracic radiologists on a scale of 0-5 for both ground-glass attenuation and fibrosis. The radiologists used three images (limited CT) and also used the entire data set (complete CT). CT scores were compared with pathology scores from 67 open and thoracoscopic biopsies. Limited and complete scores were compared with each other (Pearson correlation coefficient). Interobserver variation in the CT scoring system was assessed using kappa values.CT fibrosis scores strongly correlated with pathology fibrosis scores for complete (r = .53, p = .0001) and limited (r = .50, p = .0001) CT. CT ground-glass scores correlated with the histologic inflammatory scores for each lobe on complete (r = .27, p = .03) and limited (r = .26, p = .03) CT. The desquamative subcomponent of the pathology inflammatory score had the highest correlation with the CT ground-glass scores (complete: r = .29, p = .01; limited: r = .33, p = .007). Good interobserver agreement existed for both the alveolar and fibrosis components of the CT scoring system (kappa values ranging from .51 to .83) for each lobe of the lung on limited and complete CT.Limited thin-section CT reveals the pathologic changes associated with IPF as well as CT obtained at 10-mm increments. An added advantage of limited thin-section CT is that it exposes patients to less radiation.

We undertook this study to determine the CT findings of lipomatous hypertrophy of the interatrial septum, an asymptomatic and underrecognized benign proliferation of fat within the atrial septum.We retrospectively identified 12 cases of lipomatous hypertrophy of the interatrial septum by searching the radiology records at our institution from 1991 to 1995. We reviewed the CT scans of these patients to determine the distribution and morphology of fat within the interatrial septum.In all patients with lipomatous hypertrophy, a mass of fat attenuation extended from the coronary sinus to just above the level of the aortic root with relative sparing of the fossa ovalis, which resulted in a dumbbell configuration. Average dimensions were 7 cm for craniocaudal extent (range, 6-9 cm), 4.5 cm along the interatrial septum (range, 3.6-6.2 cm), and 2.7 cm perpendicular to the septum (range, 1.5-4.8 cm). Increased epicardial fat was seen on CT scans in 10 patients (83%). CT revealed mediastinal lipomatosis in six patients (50%). No patients had undergone corticosteroid treatment or total parenteral nutrition. No electrocardiographic or functional cardiac abnormalities were seen.On standard, high-resolution, and enhanced CT images, lipomatous hypertrophy of the interatrial septum is shown as a nonenhancing smoothly marginated homogeneous dumbbell-shaped mass of fat attenuation confined to the interatrial septum. These characteristic morphologic features allow confident diagnosis and help differentiate this benign condition from other cardiac masses.

OBJECTIVE The objective of this study was to describe the morphology of the rotator cuff tendon tears and long-term shoulder disability in conservatively treated elderly patients and determine if an association exists between these factors. METHODS Assessment of the rotator cuff tendon tear dimensions and depth, rotator interval involvement, rotator cable morphology and location, and rotator cuff muscle status was carried out on magnetic resonance studies of 24 elderly patients treated nonoperatively for rotator cuff tendon tears. Long-term shoulder function was measured using the Western Ontario Rotator Cuff (WORC) index; Disabilities of the Shoulder, Arm, and Hand questionnaire; and the American Shoulder Elbow Self-assessment form, and a correlation between the outcome scores and morphologic magnetic resonance findings was carried out. RESULTS The majority of large rotator cuff tendon tears are limited to the rotator cuff crescent. Medial rotator interval involvement (isolated or in association with lateral rotator interval involvement) was significantly associated with WORC physical symptoms total (P = 0.01), WORC lifestyle total (P = 0.04), percentage of all WORC domains (P = 0.03), and American Shoulder Elbow Self-assessment total (P = 0.01), with medial rotator interval involvement associated with an inferior outcome. CONCLUSIONS Medial rotator interval tears are associated with long-term inferior outcome scores in conservatively treated elderly patients with large rotator cuff tendon tears.

BACKGROUND Pulmonary metastases from papillary thyroid carcinoma shorten the survival of the hosts. Treatments with 131-I have been reported to induce disappearance of these tumors in a large proportion of afflicted patients. In this study, consecutive patients with diffuse micronodular lung metastases from papillary thyroid carcinoma were examined to determine if disappearance of tumor occurred, and how much disappeared, after substantial amounts of 131-I were administered. METHODS Of 232 patients treated with 131-I for thyroid carcinoma between 1985 and 1994, 12 patients between the ages of 5 and 45 years exhibited evidence of micronodular metastases to the lungs that concentrated 131-I. Each patient had undergone total or nearly total thyroidectomy and cervical lymph node dissection. All neoplasms were well differentiated papillary carcinoma, but one also had focal, poorly differentiated insular components. Follicle formation by tumors varied from less than 10% to 100% of the histologic sections. Effects of treatment were measured by three indices: chest X-ray and/or CT images, scintigraphic images, and serum thyroglobulin levels. Individual activities of 131-I ranged from 2.2 gigabequerel (GBq) (initial activity in the 5-year-old patient) to 13 GBq, and were greater than 7.4 GBq in 6 patients. Only one treatment was given to three patients, two were given to seven, and more than two were given to two. The duration of follow-up was at least one year. RESULTS In two patients, the only evidence of lung metastases was on scintigraphic images made a few days after treatment. Another patient had a normal X-ray but showed diffuse uptake of 131-I in the lungs on a diagnostic scintiscan. Of the nine patients with abnormal X-ray and CT images, seven showed improvement, but tumors disappeared in only two. In the ten patients with abnormalities on the diagnostic scintiscans, five eventually manifested no abnormality. At the outset, thyroglobulin levels exceeded 10 ng/mL in each patient; 3 individuals exhibited a decline in level by 25% or more, and a value of less than 6 ng/mL, uncomplicated by thyroglobulin antibodies, was seen in two patients. Only two patients attained normality in all three indices. Hematologic toxicity was modest and reversible. CONCLUSIONS Despite a number of previous reports that pulmonary metastases from thyroid carcinoma disappear in approximately half of patients treated with 131-I, evidence of tumor reduction was found in most, but a complete remission occurred in only 2 of 12 patients. Nevertheless, 131-I therapy may be useful to decrease the tumor burden in many such patients. Cancer 1996;78:2184-92.

To describe the radiographic appearance of extracorporeal membrane oxygenation (ECMO) in adults and to correlate lung opacity with physiologic parameters and mortality.Chest radiographs of 50 adults treated with ECMO were reviewed; pre-ECMO radiographs were available in 35 patients. Lung opacity was assigned a score of 0-4. Complications of ECMO seen at chest radiography were recorded.The lung opacity scores of the first post-ECMO radiographs were higher than those of the pre-ECMO radiographs in 17 of 35 patients (P = .0005). Maximum opacity score was significantly lower for patients who survived compared with those who died (P = .001). Twelve of 14 patients (86%) with a maximum opacity score of 4 died, compared with eight of 29 patients (28%) with a maximum score of 3. Sixteen of 26 patients (61%) with evidence of baro-trauma died, compared with six of 24 patients (25%) without pneumothorax (P = .02). Four patients developed hemothorax.Lung opacity increases immediately after initiation of ECMO. Increased opacity corresponds to decreased pulmonary function, and severe opacity correlates strongly with mortality.

Gout is an ancient disease. Last decade has brought about significant advancement in imaging technology and real scientific growth in the understanding of the pathophysiology of gout, leading to the availability of multiple effective noninvasive diagnostic imaging options for gout and treatment options fighting inflammation and controlling urate levels. Despite this, gout is still being sub-optimally treated, often by nonspecialists. Increased awareness of optimal treatment options and an increasing role of ultrasound and dual energy computed tomography (DECT) in the diagnosis and management of gout are expected to transform the management of gout and limit its morbidity. DECT gives an accurate assessment of the distribution of the deposited monosodium urate (MSU) crystals in gout and quantifies them. The presence of a combination of the ultrasound findings of an effusion, tophus, erosion and the double contour sign in conjunction with clinical presentation may be able to obviate the need for intervention and joint aspiration in a certain case population for the diagnosis of gout. The purpose of this paper is to review imaging appearances of gout and its clinical applications.

The osseous pelvis is a well-recognized site of origin of numerous primary and secondary musculoskeletal tumors. The radiologic evaluation of a pelvic lesion often begins with the plain film and proceeds to computed tomography (CT), or magnetic resonance imaging (MRI) and possibly biopsy. Each of these modalities, with inherent advantages and disadvantages, has a role in the workup of pelvic osseous masses. Clinical history and imaging characteristics can significantly narrow the broad differential diagnosis for osseous pelvic lesions. The purpose of this review is to familiarize the radiologist with the presentation and appearance of some of the common benign neoplasms of the osseous pelvis and share our experience and approach in diagnosing these lesions.

The objective of our study was to assess the prevalence, morphology, and position of the rotator cable and the relation of this structure to the rotator cuff crescent.Ultrasound examinations of bilateral shoulders of asymptomatic volunteers and of the asymptomatic shoulder in patients referred for assessment of a symptomatic contralateral shoulder were performed. The images were assessed by two radiologists for the presence of the rotator cable and measurements were performed.The rotator cable was identified in 99% of 108 asymptomatic shoulders (49 men, 59 women) (mean age, 45 years; range, 21-79 years). The mean thickness and the mean width of the rotator cable were 1.86 mm (range, 0.6-3.5 mm) and 11.5 mm (range, 7.6-17.7 mm), respectively. The mean distance between the lateral edge of the rotator cable and the medial aspect of the greater tuberosity was 8.9 mm (range, 3.6-15.4 mm). The mean rotator cuff crescent thickness was 3.7 mm (range, 2.5-5.3 mm). A statistically significant positive correlation was found between the thickness of the rotator cable and the thickness of the rotator cuff (p0.0001) and between the thickness of the rotator cuff and patient age (p=0.029).The rotator cable is a consistent structure seen in 99% of shoulders in this study. The morphology of this structure is variable, but rotator cable thickness correlated positively with the thickness of the rotator crescent.

OBJECTIVE. The purpose of this article is to show ultrasound and MRI examples of the normal anatomic structures and their resulting modifications from trauma and disease. CONCLUSION. Although groin pain from hip pathology is well recognized, lower anterior abdominal wall and anterior pelvis structures can be interrelated sources of pain.

The purpose of this study was to examine the range and prevalence of asymp tomatic findings at sonography of the shoulder.The study sample comprised 51 consecutively enrolled subjects who had no symptoms in either shoulder. Ultrasound of one shoulder per patient was performed by a musculoskeletal sonographer according to a defined protocol that included imaging of the rotator cuff, tendon of the long head of the biceps brachii muscle, subacromial-subdeltoid bursa, acromioclavicular joint, and posterior labrum. The shoulder imaged was determined at random. The 51 scans were retrospectively analyzed by three fellowship-trained musculoskeletal radiologists in consensus, and pathologic findings were recorded. Subtle or questionable findings of mild tendinosis, bursal prominence, and mild osteoarthritis were not recorded.Twenty-five right and 26 left shoulders were imaged. The subject age range was 40-70 years. Ultrasound showed subacromial-subdeltoid bursal thickening in 78% (40/51) of the subjects, acromioclavicular joint osteoarthritis in 65% (33/51), supraspinatus tendinosis in 39% (20/51), subscapularis tendinosis in 25% (13/51), partial-thickness tear of the bursal side of the supraspinatus tendon in 22% (11/51), and posterior glenoid labral abnormality in 14% (7/51). All other findings had a prevalence of 10% or less.Asymptomatic shoulder abnormalities were found in 96% of the subjects. The most common were subacromial-subdeltoid bursal thickening, acromioclavicular joint osteoarthritis, and supraspinatus tendinosis. Ultrasound findings should be interpreted closely with clinical findings to determine the cause of symptoms.

Objective. In our clinical practice, we have noted a caliber change of the posterior interosseous nerve (PIN) at the elbow as seen in the long axis on sonography simulating nerve entrapment. The objective of this study was to characterize the PIN using sonography in asymptomatic individuals. Methods. Our study retrospectively characterized the PIN in 50 elbows of 47 asymptomatic patients with sonography. Measurements of the PIN in a short-axis cross section using the circumferential trace technique and the anteroposterior (AP) dimension in the long axis were made proximal, at, and distal to the arcade of Frohse. Results. There was reduction of the AP dimension of the PIN distal to the arcade of Frohse when compared with the measurements at the arcade of Frohse and proximal to the arcade (P < .0001); however, there was no significant difference between the cross-sectional area of the PIN at all 3 levels (P = .59). Condusions. The PIN normally flattens as it enters into the supinator muscle without a notable chanqe in the cross-sectional area. This appearance should not be misinterpreted as nerve entrapment when imaged in the long axis.