Mark R. Robbin

Spinal exostoses: analysis of twelve cases and review of the literature.

Study Design. Retrospective review of spinal exostoses treated at our institution and literature review. Objectives. Review of 12 cases of spinal exostoses treated at our institution compared with 165 cases of spinal exostoses reported in the literature. Summary of Background Data. Spinal exostoses are uncommon. Most reports consist of 1 to 3 cases. The relationship between solitary exostoses and those associated with multiple hereditary exostoses (MHE), as well as the incidence of intraspinal and extraspinal location, symptoms presentation, and results of treatment are unclear. Methods. The medical records, operative reports, and diagnostic imaging of 12 patients with spinal exostoses treated at our institution between 1972 and 2002 were reviewed. The literature was reviewed using MEDLINE search of English literature and bibliographies of published manuscripts. Results. Solitary spinal exostoses were more common than those associated with MHE. Lesions were most common in the upper cervical spine and originated from the posterior elements. Patients with exostoses associated with MHE were significantly younger and had a higher incidence of symptoms consistent with neural structure compression than patients with solitary exostoses. Complete excision resulted in resolution of preoperative symptoms. Intralesional excision resulted in recurrence in all cases. Conclusions. Spinal exostoses are more common than reported previously. Patients with MHE that present with back pain or neurological symptoms should produce a high index of suspicion. Evaluation should include both computed tomography and magnetic resonance imaging to define the origin of the exostosis and the presence of neural structure compression. Surgical excision should be preformed en bloc.

Qualitative and Quantitative Performance of 18F-FDG-PET/MRI versus 18F-FDG-PET/CT in Patients with Head and Neck Cancer

BACKGROUND AND PURPOSE: MR imaging and PET/CT are integrated in the work-up of head and neck cancer patients. The hybrid imaging technology 18F-FDG-PET/MR imaging combining morphological and functional information might be attractive in this patient population. The aim of the study was to compare whole-body 18F-FDG-PET/MR imaging and 18F-FDG-PET/CT in patients with head and neck cancer, both qualitatively in terms of lymph node and distant metastases detection and quantitatively in terms of standardized uptake values measured in 18F-FDG-avid lesions. MATERIALS AND METHODS: Fourteen patients with head and neck cancer underwent both whole-body PET/CT and PET/MR imaging after a single injection of 18F-FDG. Two groups of readers counted the number of lesions on PET/CT and PET/MR imaging scans. A consensus reading was performed in those cases in which the groups disagreed. Quantitative standardized uptake value measurements were performed by placing spheric ROIs over the lesions in 3 different planes. Weighted and unweighted κ statistics, correlation analysis, and the Wilcoxon signed rank test were used for statistical analysis. RESULTS: κ statistics for the number of head and neck lesion lesions counted (pooled across regions) revealed interreader agreement between groups 1 and 2 of 0.47 and 0.56, respectively. Intrareader agreement was 0.67 and 0.63. The consensus reading provided an intrareader agreement of 0.63. For the presence or absence of metastasis, interreader agreement was 0.85 and 0.70. The consensus reading provided an intrareader agreement of 0.72. The correlations between the maximum standardized uptake value in 18F-FDG-PET/MR imaging and 18F-FDG-PET/CT for primary tumors and lymph node and metastatic lesions were very high (Spearman r = 1.00, 0.93, and 0.92, respectively). CONCLUSIONS: In patients with head and neck cancer, 18F-FDG-PET/MR imaging and 18F-FDG-PET/CT provide comparable results in the detection of lymph node and distant metastases. Standardized uptake values derived from 18F-FDG-PET/MR imaging can be used reliably in this patient population.

Gastric pneumatosis following nasogastric tube placement: a case report with literature review

We report a case of gastric emphysema following placement of nasogastric (NG) tube. Gas in the wall of the stomach is a rare finding seen in various clinical situations. The reported cases fall into two different categories: “gastric emphysema” and “emphysematous gastritis”. Differentiating these two entities is important, as the first one is usually a benign condition, but the second one carries a poor prognosis.

Influence of LVAD cannula outflow tract location on hemodynamics in the ascending aorta: a patient-specific computational fluid dynamics approach.

To develop a better understanding of the hemodynamic alterations in the ascending aorta, induced by variation of the cannula outflow position of the left ventricular assist device (LVAD) device based on patient-specific geometries, transient computational fluid dynamics (CFD) simulations using the realizable k-&egr;turbulent model were conducted for two of the most common LVAD outflow geometries. Thoracic aortic flow patterns, pressures, wall shear stresses (WSSs), turbulent dissipation, and energy were quantified in the ascending aorta at the location of the cannula outflow. Streamlines for the lateral geometry showed a large region of disturbed flow surrounding the LVAD outflow with an impingement zone at the contralateral wall exhibiting increased WSSs and pressures. Flow disturbance was reduced for the anterior geometries with clearly reduced pressures and WSSs. Turbulent dissipation was higher for the lateral geometry and turbulent energy was lower. Variation in the position of the cannula outflow clearly affects hemodynamics in the ascending aorta favoring an anterior geometry for a more ordered flow pattern. The new patient-specific approach used in this study for LVAD patients emphasizes the potential use of CFD as a truly translational technique.

Augmentation of rabbit posterolateral spondylodesis using a novel demineralized bone matrix-hyaluronan putty

Study Design. Posterolateral spinal fusion with allogeneic demineralized bone graft–hyaluronan putty in addition to autogenous iliac crest bone graft in a rabbit model. Objectives. To determine the potential efficacy of demineralized bone graft–hyaluronan putty as a bone graft enhancer. Summary of Background Data. Autograft bone is the material of choice for posterolateral lumbar intertransverse process fusion. Bone graft alternatives such as demineralized bone matrices that can be used as graft extenders, enhancers, or substitutes continue to be developed. Methods. One hundred New Zealand white rabbits underwent bilateral posterolateral spinal fusion with autogenous iliac crest bone graft or bone graft with allogeneic rabbit demineralized bone graft–hyaluronan putty. The rabbits were killed 9 weeks later, and the lumbar spines were removed. Manual manipulation and fine detail radiography were used to assess spinal fusion, and computed tomographic images were used to quantify the volume of the fusion mass. Results. In comparison with autograft bone alone, the fusion rates were greater when demineralized bone graft–hyaluronan putty was used as an adjunct to autogenous bone. Furthermore, the radiographic fusion rate was greater when demineralized bone graft–hyaluronan putty was used in a 2:1 ratio to autograft bone in comparison with a 1:1 ratio (P = 0.001). The addition of demineralized bone graft–hyaluronan putty to autograft bone was found to increase mineralized bone volume in a ratio-dependent manner (P < 0.05). Conclusions. Allogeneic demineralized bone matrix–hyaluronan putty enhances rabbit posterolateral spine fusion when used as an adjunct to autogenous bone graft. This new formulation of demineralized bone matrix may facilitate greater bone formation and successful fusion.

Accuracy and interobserver agreement for determinations of rabbit posterolateral spinal fusion

Study Design. The accuracy and interobserver agreement of fine detail radiography and computed tomography (CT) determination of spinal fusion were evaluated in an established animal spine fusion model. Objective. To determine the accuracy and interobserver agreement of radiographic determinations of spinal fusion in rabbit posterolateral spine fusion. Summary of Background Data. The rabbit posterolateral intertransverse process spine fusion model is an established animal model for evaluating bone graft alternatives for spinal fusion. However, little is known regarding the accuracy and interobserver agreement of radiographic determinations of spondylodesis in this model. Methods. Forty-two New Zealand White rabbits underwent posterolateral spinal fusion. The animals were killed at 9 weeks and the lumbar spine harvested. Manual manipulation, fine detail radiography, and CT images were used to assess spinal fusion. Results. Using manual palpation testing as the standard by which to assess fusion, there was high sensitivity and negative predictive value for both radiographic methods. Positive predictive value, however, was poor (26% fine detail radiography, 61% CT scan). CT correlated better with manual palpation testing when compared with fine detail radiographs. There was substantial interobserver agreement of successful fusion using CT scan imaging (kappa = 0.63) and moderate interobserver agreement radiographs (kappa = 0.52). Conclusions. Both radiographic techniques used in the study recorded high sensitivity and negative predictive value. However, positive predictive value was poor, especially with fine detail radiographs. Nevertheless, CT with reformatted images did appear to be superior to fine detail radiographs in accurately identifying nonunions in this animal model.

Correlation between computed tomography measurements and direct anatomic measurements of the axis for consideration of C2 laminar screw placement

BACKGROUND C2 laminar screws are becoming an increasingly used method of fixation. They allow for avoidance of fixation through the C2 pedicle, eliminating the risk of vertebral artery injury. Recent studies have described the anatomic considerations of this technique in a large cadaveric population. In clinical practice, however, direct measurement is impractical and preoperative imaging must be relied upon to determine whether or not this technique can be safely used. PURPOSE To evaluate the ability of computed tomography (CT) to accurately assess critical dimensions of the C2 vertebrae with regard to intralaminar screw placement. STUDY DESIGN/SETTING Cadaveric analysis. METHODS The C2 vertebrae of 84 adult spines were randomly selected from a large cadaveric collection. Direct measurements were performed to determine laminar thickness, estimated screw length, and spinolaminar angle. Fine cut axial CT scans were then performed on all specimens and all measurements were repeated from these images. Correlation coefficients were calculated to determine the ability of CT scan to accurately determine these measurements. RESULTS CT scan measurements were found to be highly correlated with direct measurements for both left and right mean laminar thickness (0.975 and 0.947, respectively). Screw lengths using CT scan were found to be significantly longer than previously reported direct measurements (24.8 vs. 28.8mm; p<.01). The mean CT spinolaminar angle was 42.45 degrees, whereas it was 48.47 degrees on direct measurement. Correlation coefficient for spinolaminar angle measurements was low (0.23); however, this is likely because of measurement variability. CONCLUSIONS Given the high degree of correlation between CT measurements and direct anatomic measurements, we conclude that CT scan can accurately determine laminar thickness, a measurement critical to safe placement of intralaminar screws. It appears that longer screw lengths that were previously reported may be safely used while remaining intra-osseous. We continue to advocate preoperative planning using CT to identify patients whose lamina may be unable to accommodate safe screw placement using this technique.

Tumoral calcinosis in the cervical spine in a patient with CREST syndrome. A case report.

T umoral calcinosis is characterized by tumor-like periarticular deposits of calcium, and it commonly presents as a growing calcific mass in the soft tissue surrounding major joints1-6. It may be associated with bone erosion and destruction and may have a mass effect on neurovascular structures7-9. Tumoral calcinosis can be a component of CREST syndrome, an acronym for calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia. Spinal and paraspinal tumoral calcinosis has been reported to involve both the vertebral bodies and the posterior elements of the cervical, thoracic, and lumbar spine6,10-18. To our knowledge, tumoral calcinosis of the cervical spine as a component of CREST syndrome has been reported in only three patients7,8,10. The diagnosis of tumoral calcinosis in the spine is difficult because of its rarity and its ability to mimic a neoplasm or infectious cause6,14,16,19. Neurologic deficits by mass effect can occur and may manifest as radiculopathy and/or myelopathy7-10,18. Moreover, it has been shown that tumoral calcinosis of the spine has presented diagnostic dilemmas to clinicians, radiologists, and pathologists because of a lack of familiarity with the entity16. We report the clinical presentation, radiographic findings, histopathologic results, and the surgical management of tumoral calcinosis of the cervical spine in a patient with CREST syndrome. Our patient is unique in that there was radiographic evidence of rapid progression of bone erosion and crystal deposition involving the posterior elements and paraspinal tissues within a one-year period. In addition, an anomalous, single vertebral artery on the affected side supplied the basilar artery system. The patient was informed that data concerning the case would be submitted for …

Correlation of muscle BOLD MRI with transcutaneous oxygen pressure for assessing microcirculation in patients with systemic sclerosis.

To prospectively compare calf muscle BOLD MRI with transcutaneous oxygen pressure (TcPO2) measurement in patients with systemic sclerosis (SSc) and healthy volunteers and thereby get insight into the pathogenesis of vasculopathy in this connective tissue disorder.

Initial experience of MR/PET in a clinical cancer center.

Magentic Resonance/positron emission tomography (PET) has been introduced recently for imaging of clinical patients. This hybrid imaging technology combines the inherent strengths of MRI with its high soft‐tissue contrast and biological sequences with the inherent strengths of PET, enabling imaging of metabolism with a high sensitivity. In this article, we describe the initial experience of MR/PET in a clinical cancer center along with a review of the literature. For establishing MR/PET in a clinical setting, technical challenges, such as attenuation correction and organizational challenges, such as workflow and reimbursement, have to be overcome. The most promising initial results of MR/PET have been achieved in anatomical areas where high soft‐tissue and contrast resolution is of benefit. Head and neck cancer and pelvic imaging are potential applications of this hybrid imaging technology. In the pediatric population, MR/PET can decrease the lifetime radiation dose. MR/PET protocols tailored to different types of malignancies need to be developed. After the initial exploration phase, large multicenter trials are warranted to determine clinical indications for this exciting hybrid imaging technology and thereby opening new horizons in molecular imaging. J. Magn. Reson. Imaging 2014;39:768–780.