Ara Kassarjian

Tumor Burden in Patients with Neurofibromatosis Types 1 and 2 and Schwannomatosis: Determination on Whole-Body MR Images

PURPOSE To develop a three-dimensional (3D) segmentation and computerized volumetry technique for use in the assessment of neurofibromatosis and to assess the ability of this technique to aid in the calculation of tumor burden in patients with neurofibromatosis types 1 and 2 (NF1 and NF2, respectively) and schwannomatosis detected with whole-body magnetic resonance (MR) imaging. MATERIALS AND METHODS Institutional review board approval and written informed consent were obtained for this prospective HIPAA-compliant study. Fifty-two subjects (27 women, 25 men; mean age, 42 years +/- 15 [standard deviation]; age range, 24-86 years) underwent whole-body MR imaging performed with coronal short inversion time inversion-recovery (STIR) sequences. Whole-body tumor burden was estimated with a 3D segmentation method (the dynamic-threshold [DT] level set method) in 29 subjects (16 with NF1, six with NF2, and seven with schwannomatosis) in whom at least one nerve sheath tumor was reliably identified on MR images. Fifty tumors (25 plexiform and 25 discrete tumors) were randomly selected and subjected to manual and computerized volumetry to assess reliability. Ten plexiform tumors 5 cm or larger in diameter were retrospectively selected and segmented with three initialization methods for computerized volumetry and manually contoured by three radiologists to assess repeatability. Bland-Altman analysis was performed, and intraclass correlation coefficients (ICCs) were calculated. RESULTS A total of 398 nerve sheath tumors (185 plexiform and 213 discrete tumors) were identified in 29 subjects. Volumetric measurements obtained with the computerized method and manual contouring were highly correlated (r(ICC) = 0.99). Bland-Altman analysis showed that computerized volumetry had a mean difference of -2.6% compared with manual volumetry. The repeatability coefficient of the computerized scheme was +/-5% compared with +/-30% for manual contouring. CONCLUSION This 3D segmentation and computerized volumetry technique is reliable relative to manual segmentation and has the advantage of being less labor intensive and more repeatable. This technique can be paired with whole-body MR imaging to determine tumor burden in patients with neurofibromatosis. SUPPLEMENTAL MATERIAL http://radiology.rsnajnls.org/cgi/content/full/250/3/665/DC1

The accuracy of computed tomography for the diagnosis of tibial nonunion

BACKGROUND When a patient is seen with a possible tibial nonunion and equivocal findings on plain radiographs, the surgeon may choose to obtain a computed tomography scan to better delineate the bone anatomy. However, the sensitivity and specificity of computed tomography in this setting is not known. We investigated the accuracy of computed tomography for detecting nonunion in this clinical situation. METHODS Thirty-five patients with equivocal findings on plain radiographs underwent computed tomography scanning. The patients were first seen at an average of 9.7 months after the injury and had undergone a mean of 2.6 prior operations. A so-called gold standard of union or nonunion was determined by either surgical findings (for twenty-five patients who were operatively treated) or six months of clinical observation (for ten patients who had nonoperative treatment). Computed tomography scans were assessed by two radiologists and one orthopaedic surgeon who were blinded to the clinical outcome. RESULTS Computed tomography scans displayed very good diagnostic accuracy. Intraobserver agreement was high (intraclass correlation coefficient = 0.89), the sensitivity for detecting nonunion was 100%, and the overall accuracy was 89.9%. Computed tomography was limited by a low specificity of 62%, as three patients who were diagnosed as having tibial nonunion with computed tomography underwent surgery and were found to have a healed fracture. CONCLUSIONS Computed tomography displays very good accuracy in the evaluation of tibial fracture-healing. However, it is limited by low specificity and may sometimes misrepresent a healed fracture as a nonunion. Surgeons must be aware of this pitfall in order to accurately determine which patients need surgical intervention.

Quantitative Assessment of Whole-Body Tumor Burden in Adult Patients with Neurofibromatosis

Purpose Patients with neurofibromatosis 1 (NF1), NF2, and schwannomatosis are at risk for multiple nerve sheath tumors and premature mortality. Traditional magnetic resonance imaging (MRI) has limited ability to assess disease burden accurately. The aim of this study was to establish an international cohort of patients with quantified whole-body internal tumor burden and to correlate tumor burden with clinical features of disease. Methods We determined the number, volume, and distribution of internal nerve sheath tumors in patients using whole-body MRI (WBMRI) and three-dimensional computerized volumetry. We quantified the distribution of tumor volume across body regions and used unsupervised cluster analysis to group patients based on tumor distribution. We correlated the presence and volume of internal tumors with disease-related and demographic factors. Results WBMRI identified 1286 tumors in 145/247 patients (59%). Schwannomatosis patients had the highest prevalence of tumors (P = 0.03), but NF1 patients had the highest median tumor volume (P = 0.02). Tumor volume was unevenly distributed across body regions with overrepresentation of the head/neck and pelvis. Risk factors for internal nerve sheath tumors included decreasing numbers of café-au-lait macules in NF1 patients (P = 0.003) and history of skeletal abnormalities in NF2 patients (P = 0.09). Risk factors for higher tumor volume included female gender (P = 0.05) and increasing subcutaneous neurofibromas (P = 0.03) in NF1 patients, absence of cutaneous schwannomas in NF2 patients (P = 0.06), and increasing age in schwannomatosis patients (p = 0.10). Conclusion WBMRI provides a comprehensive phenotype of neurofibromatosis patients, identifies distinct anatomic subgroups, and provides the basis for investigating molecular biomarkers that correlate with unique disease manifestations.

Magnetic resonance imaging of the hip: sports-related injuries.

Normal hip disorders do not account for a large proportion of exercise-related injuries, but they can pose a clinical dilemma because symptoms tend to be nonspecific. Conventional radiographs may demonstrate some causes of hip pain, such as stress fractures and degenerative joint disease. Magnetic resonance imaging (MRI) of the hip has proven valuable in the diagnosis of radiographically occult osseous abnormalities and periarticular soft-tissue disorders such as stress fractures, avulsion injuries, musculotendinous abnormalities, and bursitis. Conventional MRI has been less useful in the evaluation of intra-articular lesions, including acetabular labral tears, intra-articular loose bodies, and cartilage lesions. Visualization of intra-articular structures and their abnormalities can be improved by injection of diluted gadolinium, which distends the capsule and leaks into labral tears. This article focuses on the use of conventional radiography and MRI in recreational and professional athletes with painful hip joints. Where possible, MRI is compared with other diagnostic modalities such as bone scan and computed tomography.

Incidence and MR imaging features of fractures of the anterior process of calcaneus in a consecutive patient population with ankle and foot symptoms

ObjectiveTo determine the incidence, appearances and associated injuries of fractures affecting the anterior process of calcaneus from a general population with foot and ankle symptoms.Design and patientsA retrospective review of foot and ankle MR imaging procedures was performed for detection of cases with a fracture affecting the anterior process of calcaneus over a four year period. Radiographs, MR imaging studies, radiology reports, medical records, and operative notes were reviewed. Imaging analysis included fracture pattern, displacement, associated fractures, and presence of tendon and ligamentous injuries.ResultsThe incidence of anterior process of calcaneus fracture on MR imaging was 0.5% (14/2577). Fractures were more common in female subjects (71%, 10/14). Fracture orientation was predominantly vertical (93%, 13/14). No comminuted fractures were seen and only three fractures were displaced. Three of the eight MR imaging evident fractures of anterior process of calcaneus were seen on radiographs. Associated fractures of the talus (n=5), navicular bone (n=3), cuboid (n=2), and calcaneal body (n=1) were noted. Associated injuries to the anterior talofibular ligament (n=3) and tears of the peroneus brevis (n=3) and peroneus longus (n=1) tendons were present. All fractures were treated non-operatively. Two patients had subtalar joint steroid injection for symptomatic relief.ConclusionsFractures of the anterior process of the calcaneus are uncommon in MR examinations of a general population of patients with foot and ankle symptoms. Although anterior process of calcaneus fractures are rare, there was a moderately high incidence of associated bone and soft-tissue injuries.

Distal clavicular osteolysis: MR evidence for subchondral fracture

PurposeTo investigate the association between distal clavicular osteolysis and subchondral fractures of the distal clavicle at MRI.Materials and methodsThis study was approved by the hospital human research committee, which waived the need for informed consent. Three radiologists retrospectively analyzed 36 shoulder MR examinations in 36 patients with imaging findings of distal clavicular osteolysis. The presence of a subchondral fracture of the distal clavicle, abnormalities of the acromioclavicular joint, rotator cuff tears and labral tears were assessed by MRI. These cases were then compared with 36 age-matched controls.ResultsAt MRI, 31 of 36 patients (86%) had a subchondral line within the distal clavicular edema, consistent with a subchondral fracture. Of the 36 patients, 32 (89%) had fluid in the acromioclavicular joint, while 27 of 36 patients (75%) had cysts or erosions in the distal clavicle. There were 13 patients (36%) with associated labral tears, while eight patients (22%) had partial-thickness rotator cuff tears. In the control group one of 36 (3%) had a subchondral line (P<0.05), while ten of 36 (28%) had rotator cuff tears and 13 of 36 (36%) had labral tears. These latter two were not statistically significant between the groups.ConclusionA distal clavicular subchondral fracture is a common finding in patients with imaging evidence of distal clavicular osteolysis. These subchondral fractures may be responsible for the propensity of findings occurring on the clavicular side of the acromioclavicular joint.

Femoroacetabular impingement: presentation, diagnosis, and management.

Femoroacetabular impingement (FAI) is an often overlooked cause of hip pain in patients of all ages. The clinical signs and symptoms, multimodality imaging findings, treatment options, intraoperative findings, and expected outcomes for patients with FAI are illustrated and discussed.

Relationship between whole‐body tumor burden, clinical phenotype, and quality of life in patients with neurofibromatosis

Patients with neurofibromatosis 1 (NF1), NF2, and schwannomatosis share a predisposition to develop multiple nerve sheath tumors. Previous studies have demonstrated that patients with NF1 and NF2 have reduced quality of life (QOL), but no studies have examined the relationship between whole‐body tumor burden and QOL in these patients. We administered a QOL questionnaire (the SF‐36) and a visual analog pain scale (VAS) to a previously described cohort of adult neurofibromatosis patients undergoing whole‐body MRI. One‐sample t‐tests were used to compare norm‐based SF‐36 scores to weighted population means. Spearman correlation coefficients and multiple linear regression analyses controlling for demographic and disease‐specific clinical variable were used to relate whole‐body tumor volume to QOL scales. Two hundred forty‐five patients (142 NF1, 53 NF2, 50 schwannomatosis) completed the study. Subjects showed deficits in selected subscales of the SF‐36 compared to adjusted general population means. In bivariate analysis, increased tumor volume was significantly associated with pain in schwannomatosis patients, as measured by the SF‐36 bodily pain subscale (rho = −0.287, P = 0.04) and VAS (rho = 0.34, P = 0.02). Regression models for NF2 patients showed a positive relationship between tumor burden and increased pain, as measured by the SF‐36 (P = 0.008). Patients with NF1, NF2, and schwannomatosis suffer from reduced QOL, although only pain shows a clear relationship to patients overall tumor burden. These findings suggest that internal tumor volume is not a primary contributor to QOL and emphasize the need for comprehensive treatment approaches that go beyond tumor‐focused therapies such as surgery by including psychosocial interventions.

Synovial plicae of the hip: evaluation using MR arthrography in patients with hip pain.

ObjectiveThe appearance and distribution of the intra-articular plicae of the hip have been addressed in few reports in the anatomic and radiological literature. This study aims to determine the prevalence of visible synovial hip plicae using MR arthrography and to measure the association of visible synovial hip plicae with MR arthrographic diagnosis of labral tears, femoroacetabular impingement, and osteoarthritis.Materials and methodsFollowing institutional review board approval, 63 direct MR arthrographic examinations of the hip in 61 patients with a clinical history of hip pain were retrospectively reviewed by two experienced musculoskeletal radiologists in consensus. The following variables were measured using a binary system (0 = absent; 1 = present): labral plica, neck plica, ligamental plica, labral tear, femoroacetabular impingement, and osteoarthritis. The surgical reports and arthroscopic images of 10 patients were reviewed. Statistical analysis was performed using the Fisher’s exact test.ResultsIn all 63 cases at least one plica was visualized on MR-arthrographic images. Labral, neck, and ligamental plicae were found with a prevalence of 76, 97, and 78%, respectively. There was no statistically significant association between the presence of labral tears, femoroacetabular impingement, and osteoarthritis among patients with visible labral, neck, and ligamental plicae. The prevalence of labral tears, femoroacetabular impingement, and osteoarthritis in our patient population was 79, 28, and 28%, respectively. The presence of intra-articular plicae was the only MR-arthrographic finding in 5 of our 63 symptomatic cases.ConclusionVisible labral, neck, and/or ligamental plicae are highly prevalent on MR-arthrographic images of the hip performed in the setting of hip pain. There was no statistically significant association between the presence of labral tears, femoroacetabular impingement, and osteoarthritis and visible labral, neck, and ligamental plicae.

Bone marrow changes in stress injuries.

Stress injuries and associated bone marrow changes are a common finding in athletes of all levels. Magnetic resonance imaging (MRI) is the imaging modality of choice for detecting characterizing and staging these injuries. However, because bone marrow edema patterns may also be seen in asymptomatic athletes, it is imperative for the sports medicine physician and the radiologist to closely correlate the imaging findings with the clinical signs and symptoms to assess the clinical significance of the imaging findings. This article reviews the pathophysiology, MRI findings, and clinical implications of stress injuries in athletes.