Accuracy of chemical shift MR imaging in diagnosing indeterminate bone marrow lesions in the pelvis: review of a single institution's experience.

OBJECTIVE: To re-assess the accuracy of chemical shift imaging in diagnosing indeterminate bone marrow lesions as benign or malignant. MATERIALS AND METHODS: We retrospectively reviewed our experience with MR imaging of the pelvis to assess the accuracy of chemical shift imaging in distinguishing benign from malignant bone lesions. Two musculoskeletal radiologists retrospectively reviewed all osseous lesions biopsied since 2006, when chemical shift imaging was added to our routine pelvic imaging protocol. Study inclusion criteria required (1) MR imaging of an indeterminate bone marrow lesion about the pelvis and (2) subsequent histologic confirmation. The study group included 50 patients (29 male, 21 female) with an average age of 67 years (range, 41-89 years). MR imaging results were evaluated using biopsy results as the "gold standard." RESULTS: There were 27 malignant and 23 benign lesions. Chemical shift imaging using an opposed-phase signal loss criteria of less than 20 % to indicate a malignant lesion, correctly diagnosed 27/27 malignant lesions and 14/23 benign lesions, yielding a 100 % sensitivity, 61 % specificity, 75 % PPV, 100 % NPV, and 82 % accuracy. The area under the receiver operator characteristic (ROC) curve was 0.88. The inter-rater and intra-rater agreement K values were both 1.0. CONCLUSIONS: Chemical shift imaging is a useful adjunct MR technique to characterize focal and diffuse marrow abnormalities on routine non-contrast pelvic imaging. It is highly sensitive in identifying malignant disease. Despite its lower specificity, the need for biopsy could be eliminated in more than 60 % of patients with benign disease.

Diagnosis of proximal femoral insufficiency fractures in patients receiving bisphosphonate therapy.

OBJECTIVE: The purpose of this article is to describe the imaging features of proximal femoral insufficiency fractures in patients on long-term bisphosphonate therapy. CONCLUSION: The imaging findings of bisphosphonate-related femoral insufficiency fractures, which include a typical proximal diaphyseal location and transverse liner radiolucency through localized thickening of the lateral cortex, allow a specific diagnosis.

The importance of sagittal 2D reconstruction in pelvic and sacral trauma: avoiding oversight of U-shaped fractures of the sacrum.

OBJECTIVE: The U-shaped sacral fracture can be overlooked without appropriate imaging. Radiographic and CT imaging of seven patients with U-shaped sacral fractures was reviewed. CONCLUSION: Although it is difficult to discern on anteroposterior radiographs and axial or coronal CT, the fracture is easily identifiable on CT images in the sagittal plane. We advocate reconstruction of CT images of the sacrum in the sagittal plane in trauma to prevent failure of identification.

Nephrogenic systemic fibrosis in liver disease: a systematic review.

Nephrogenic systemic fibrosis (NSF) may develop in patients with liver disease, a fact highlighted by Food and Drug Administration (FDA) announcements cautioning against the use of gadolinium-based contrast agents (GBCAs) in select liver disease patients. The purpose of this systematic literature review is to characterize the risk of NSF in patients with liver disease. All published articles on NSF from September 2000 through August 2008, were identified via PubMed searches and examination of articles' reference lists. Two reviewers independently read each article and identified unique patients with biopsy-proven or suspected NSF. Data on demographics, liver status, renal status, and GBCA exposure were collected. A total of 324 articles were reviewed, with 108 articles containing case descriptions of 335 unique NSF patients. After excluding the 95/335 (28%) patients in whom the presence or absence of liver disease was uncertain, liver disease was confirmed present in 41/239 (17%) patients. Renal insufficiency could be assessed in 35 of the liver disease patients; severe renal insufficiency, defined as a glomerular filtration rate (GFR) or estimated GFR (eGFR) <30 mL/min/1.73 m(2) or dialysis requirement, was present in 34/35 (97%) patients. The lone patient who developed NSF with mild/moderate renal insufficiency was atypical and received a total gadodiamide load of 0.76 mmol/kg over a 10-week period periliver transplantation. The published medical literature demonstrates that patients with liver disease who develop NSF also have severe renal insufficiency, suggesting that liver disease does not confer a risk for NSF beyond that of the underlying renal insufficiency. J. Magn. Reson. Imaging 2009;30:1313-1322. (c) 2009 Wiley-Liss, Inc.

Effect of shot number on the calculated apparent diffusion coefficient in phantoms and in human liver in diffusion-weighted echo-planar imaging.

PURPOSE: To show the signal intensity varies with shot number in diffusion-weighted (DW) echo-planar imaging (EPI) and affects apparent diffusion coefficient (ADC) calculation. MATERIALS AND METHODS: This prospective study was performed on 35 adult patients and 20 volunteers. Measurements were made on a 3T scanner using a breathhold DW spin-echo EPI (SE EPI) sequence. Three protocols were used: A) eight consecutive shots at a fixed b-value of 0 seconds/mm(2) with TR = 1000 and 3000 msec; B) seven consecutive shots at b-values = 0, 1000, 750, 500, 250, 100, 0 seconds/mm(2) (in that order) with TR = 3500 msec; and C) seven consecutive shots (as in B) with TR = 1000, 1750, and 7000 msec. RESULTS: For protocol A, signal intensity decreased significantly from the first to second shot (P<0.0001) and thereafter remained constant. For protocol B, the ADC depended on which b = 0 seconds/mm(2) image was used. Using the first b = 0 seconds/mm(2), the mean ADC was 15% higher than using the second b = 0 seconds/mm(2) (P<0.0001). For protocol C, the difference between ADC using the first b = 0 seconds/mm(2) and the second b = 0 seconds/mm(2) decreased as the TR increased. CONCLUSION: The signal intensity can vary with shot number in SE EPI. For TR > or = 3000 msec, steady-state is attained after one shot. Using data acquired prior to steady-state confounds the calculation of ADC values.

Computed tomography imaging of patients with obstructive sleep apnea.

OBJECTIVES/HYPOTHESIS: This study used computed tomography (CT) to identify anatomic features of the awake upper respiratory tract (URT) that correlate with severity of obstructive sleep apnea (OSA). STUDY DESIGN: An IRB approved radiographic study of 80 patients with OSA and 56 patients from the general population. METHODS: Awake, noncontrast CT was performed from the skull base to the thoracic inlet in patients with OSA. Cross-sectional measurements of the retropalatal and retrolingual airways were made along with the size of the cervicomandibular ring and the percentage neck fat. The mandibular plane to hyoid distance, neck length, and laryngeal descent were also recorded. The posterior tongue fat content was estimated using the Hounsfield unit for radiodensity. The radiographic data were then compared with clinical information, including apnea-hypopnea index (AHI), body mass index, and neck circumference using linear regression. RESULTS: AHI increases with smaller retrolingual cross-sectional airway (P = .0026) and increasing mandibular plane to hyoid distance (P = .0003) but not retropalatal airway or laryngeal descent. The posterior tongue is hypodense with higher fat content than other muscles of the head and neck. CONCLUSIONS: This study describes anatomic findings of the retrolingual airway in patients that correlate with OSA and can be measured on an upper airway CT. Patients with severe OSA (AHI > or = 40) tend to have retrolingual airways less than 4% of the cross-sectional area of the cervicomandibular ring. The retrolingual airspace is the major site of obstruction in severe OSA and should be carefully evaluated before surgical treatment is considered.