The prevalence of vertebral fracture on vertebral fracture assessment imaging in a large cohort of patients with rheumatoid arthritis.

OBJECTIVE: RA accelerates bone loss, increasing the risk of osteoporosis (OP) and fracture. DXA imaging has been validated for identifying RA patients at risk of fracture. The objective of this study was to assess the presence of asymptomatic vertebral fractures (VFs) in a cohort of patients with established RA referred for DXA using VF assessment (VFA) technology. METHODS: We determined the prevalence of VFs in a cohort of RA patients age ≥ 40 years fulfilling the 1987 ACR classification criteria. Two blinded radiologists independently reviewed all VFA scans to determine the presence and severity of VFs using Genant criteria. We compared the prevalence and severity of VFs between RA patients and determined the independent associations of different variables with VFs using multivariable logistic regression. RESULTS: Six hundred and three subjects fulfilled study inclusion criteria. Thirteen per cent of the entire cohort (77/603) had one or more vertebral deformities identified on VFA imaging: 58% were female with mean age 56 years. The prevalence of OP and osteopenia was 59% and 40%, respectively. The prevalence and severity of VFs showed significant correlation with spine T-scores (r = -0.37, P < 0.001) and femoral T-scores (r = -0.31, P < 0.001). In multivariable analyses VFs were significantly and independently associated with a longer duration of RA, markers of disease activity and severity. CONCLUSION: VFs were detected on VFA images in 13% of women and men with well-established RA referred for DXA testing. Longer duration and severity of RA disease were independent risk factors for fractures in our study.

Evaluation of imaging quality of pulmonary 64-MDCT angiography in pregnancy and puerperium.

OBJECTIVE: The aim of this study was to quantitatively and qualitatively evaluate pulmonary 64-MDCT angiography image quality in pregnancy and puerperium, compared with female nonpregnant control subjects. MATERIALS AND METHODS: The study group comprised 124 consecutive pregnant and postpartum women and 124 female nonpregnant control subjects who presented with suspected pulmonary embolism. The individual studies were evaluated for subjective and objective diagnostic quality. RESULTS: Objective measurements of the arterial enhancement in the pulmonary trunk and left and right pulmonary arteries found that there was no statistically significant difference in attenuation values between the pregnant and puerperium group and the control group for pulmonary artery opacification. The mean attenuation in the pulmonary trunk was 270.54 HU in the pregnant group, 277.53 HU in the puerperium group, and 293.90 HU in the control group. CONCLUSION: We found no significant difference in diagnostic quality of pulmonary CT angiography using MDCT between the study and control groups. The use of MDCT acquisition, faster injection rates, higher contrast medium concentration, and higher trigger levels may decrease the number of nondiagnostic studies in this population. MDCT may be a worthwhile investigation in the majority of pregnant patients with suspected pulmonary embolism.

The prevalence of aortic calcification on vertebral fracture assessment imaging among patients with rheumatoid arthritis.

Patients with rheumatoid arthritis (RA) are at increased risk of osteoporosis (OP) and cardiovascular disease (CVD). Dual-energy X-ray absorptiometry scans have been validated for identifying patients with RA at risk for fracture. Reliable CVD risk stratification remains an unmet need in this population. Vertebral fracture assessment (VFA)-detected abdominal aortic calcification (AAC) has been validated as a marker of CVD in other populations, but the prevalence among patients with RA is unknown. In this study, we determined the prevalence and severity of AAC on VFA scans in a cohort of patients with RA. AAC was detected in 211 of the 603 (35%) eligible subjects; 24% were graded as severe. In multivariable analyses, the presence of AAC was significantly associated with longer disease duration and higher disease activity (p<0.05). Further studies are needed on the relationship between AAC and CVD in patients with RA.

Does MRI with oral contrast medium allow single-study depiction of inflammatory bowel disease enteritis and colitis?

OBJECTIVE: To assess the feasibility and utility of magnetic resonance (MR) imaging of the bowel in concurrent small- and large-bowel evaluation for the presence of inflammatory bowel disease (IBD). METHODS: Over a 5-year period, 62 MR examinations performed on 53 patients demonstrated evidence of IBD. Sixteen of these 53 (30.1%) patients had imaging findings of colonic disease and underwent 19 formal MR small bowel examinations. These were further evaluated for bowel distention and image quality. The sensitivity and specificity of the technique compared with colonoscopy as the 'gold standard' was evaluated. RESULTS: Simultaneous imaging of the colon is feasible at MR small bowel follow-through with moderate-to-excellent colonic visibility and colon distention obtained when the contrast medium is present in the colon at the time of image acquisition. MR imaging had a sensitivity of 80% (0.56-0.93), specificity of 100% (0.77-1.00), positive predictive value (PPV) of 1 and a negative predictive value (NPV) of 0.8 for the identification of colitis (based on available concurrent correlation of 38/62 examinations with colonoscopy). CONCLUSION: Small and large bowel MR imaging with orally consumed contrast medium represents a promising, feasible, non-invasive, non-radiating single mode of assessment of the entire gastrointestinal tract, performed at a single sitting.

Isolated limb infusion: technique description and clinical application.

Isolated limb infusion (ILI) is a recently described minimally invasive technique indicated in the management of regionally advanced cancers refractory to systemic therapy and surgery. The present report describes the initial single-center experience of three patients with regionally advanced peripheral melanoma and one with lower-extremity cutaneous T-cell lymphoma treated over a period of 1 year. It is feasible to perform the complete ILI procedure in a single 60-100-minute session, solely in the interventional radiology suite, without a requirement for patient transfer to the operating room or extra waiting time between catheter insertion and chemotherapy infusion treatment.

MR small-bowel follow-through for investigation of suspected pediatric small-bowel pathology.

OBJECTIVE: The purpose of our study was to evaluate the potential role of an MR small-bowel follow-through (SBFT) technique in the investigation of suspected pediatric small-bowel abnormalities. MATERIALS AND METHODS: Between September 2003 and January 2008, 280 MR SBFT examinations were performed for investigation of known or suspected small-bowel abnormalities, including 19 of 280 examinations in 17 children (mean age, 13 years; age range 6-17 years), representing the current study population. A standardized technique was used in all cases, including axial and coronal steady-state free precession acquisitions at successive time intervals until completion. Retrospective analysis of the studies obtained was performed by two radiologists, who blindly and independently scored predefined small-bowel segments according to the degree of luminal distention achieved. Any pathologic lesions detected were also noted. Indicators of examination success as a whole (volume, tolerability, and side effects of oral contrast material) were also noted, as were details pertaining to examination duration (number of visits to the MR table, total table time). RESULTS: Oral contrast medium was ingested and subsequent imaging was possible in all patients; 84.2% of patients tolerated the oral contrast material well and 15.8% showed moderate tolerance. The MR table time ranged from 2 to 4 minutes, without early termination of the examination in any case. The average number of visits to the MR table was 1.3 (range, 1-3). The mean duration for complete small-bowel evaluation was 25 minutes (range, 20-60 minutes). The mean distention scores were well within the diagnostic range in all small-bowel segments for both observers, with a substantial degree of interobserver agreement in score assignment (kappa = 0.73). Pathologic lesions were identified in 53% of studies. CONCLUSION: MR SBFT represents a promising, and perhaps optimal, technique for pediatric small-bowel evaluation for a variety of reasons, including its high tolerability, lack of ionizing radiation, avoidance of duodenojejunal intubation, and excellent luminal distention achieved. Furthermore, this technique allows "pseudodynamic" functional imaging while also showing extraluminal disease, without known biologic risk.

Cam-type femoral-acetabular impingement: is the alpha angle the best MR arthrography has to offer?

INTRODUCTION: In our institutional experience, determination of the alpha (alpha) angle at MR arthrography as an indicator of the likelihood of cam-type femoroacetabular impingement (FAI) is fraught with inconsistency. The aims of this study were to quantify the degree of variability in and calculate the diagnostic accuracy of the alpha angle in suggesting a diagnosis of cam impingement, to determine the accuracy of a positive clinical impingement test, and to suggest alternative MR arthrographic measures of femoral head-neck overgrowth and determine their diagnostic utilities. MATERIALS AND METHODS: We carried out a retrospective analysis of MR arthrographic studies performed during a 4-year period, combined with chart analysis, which allowed identification of 78 patients in whom surgical correlation was also available. The status of a preoperative clinical impingement test was also noted. Patients were designated as having cam-type FAI (Group A, n = 39) if intra-operative femoral head-neck junction bony osteochondroplasty/arthoscopic femoral debridement was performed. Group B (n = 39) acted as controls. Three radiologists independently and blindly performed a series of measurements (alpha angle and two newly proposed measurements) in each patient on two separate occasions. An alpha angle of greater than 55 degrees was considered indicative of the presence of cam-type FAI. RESULTS: Performance values for alpha angle measurement were poor for each observer. There was considerable (up to 30% of the mean value) intra-observer variability between the first and second alpha angle measurements for each subject. Binary logistic regression analysis confirmed that the alpha angle is of no value in predicting the presence or absence of cam-FAI. A statistically significant difference existed between Groups A and B with regard to the newly proposed anterior femoral distance (AFD; p = 0.004). Using an AFD value of 3.60 mm or greater as being indicative of the presence of cam-FAI yields a 0.67 performance measure (95% confidence interval 0.55-0.79). The second proposed parameter (femoral neck ratio) was of no value in suggesting the presence or absence of this condition. The sensitivity, specificity, and positive and negative predictive values of the clinical impingement test were 76.9%, 87.2%, 85.7% and 79.1% respectively. CONCLUSIONS: Femoral alpha angle measurement is associated with considerable variability. This index performed poorly in our patient population and was statistically of no value in suggesting the presence or absence of cam-FAI. One of our proposed measures, the AFD, outperformed the alpha angle, though to an insufficient degree to suggest its routine incorporation into clinical practice. Our experience suggests that the clinical impingement test remains the most reliable predictor of the presence of this condition.

Changes in left ventricular shape and morphology in the presence of heart failure: a four-dimensional quantitative and qualitative analysis.

PURPOSE: The presence and progression of heart failure (HF) are associated with cardiac remodelling, defined as cellular, molecular and interstitial changes which occur after injury and manifest as changes in left ventricular (LV) size, mass, geometry and function. This research study was designed to investigate the changes to LV morphology and shape which occur in the presence of heart failure using three-dimensional (3D) modelling and analysis of cardiac-gated CT scans from both healthy individuals and patients classified with HF. METHODS: A number of quantitative and qualitative strategies were applied to cardiac CT scans of HF patients and healthy controls (n = 7) in order to analyse changes to LV size, shape and structure and to examine LV remodelling in the different classes of HF. Three-dimensional wireframe representations of endocardial and epicardial borders were created, three-dimensional computer stereolithography models of the inner LV cavity and myocardial wall segments were generated and three-dimensionally printed and a number of clinical LV dimension and shape indices were measured. All data were analysed using one-way ANOVA with post hoc Tukey method for multiple comparisons for significant variables. RESULTS: Results of most significance included abnormalities in LV mass and end-systolic dimensions and significantly increased septal wall thickness among mid-range ejection fraction cases. Also of importance were significant increases in both dimension-based and volumetric sphericity index measures in all HF cases. Three-dimensional printed models provided qualitative information as to changes in inner LV cavity and myocardial wall morphology across the cardiac cycle for healthy and HF cases and validated quantitative findings. CONCLUSION: Findings from this study can successfully be applied to motivate the research and development of new HF treatment strategies and devices as well as for the development of a realistic cardiac simulator system.

Supraaortic arteries: contrast material dose reduction at 3.0-T high-spatial-resolution MR angiography--feasibility study.

PURPOSE: To evaluate and compare the diagnostic image quality resulting from three contrast agent dose regimens for 3.0-T high-spatial-resolution three-dimensional magnetic resonance (MR) angiography of the supraaortic arteries. MATERIALS AND METHODS: Institutional review board approval was obtained; informed consent was waived for this HIPAA-compliant study. One hundred twenty consecutive patients who underwent 3.0-T three-dimensional high-spatial-resolution contrast material-enhanced MR angiography of the supraaortic arteries with an identical acquisition protocol were assigned to either the high-dose (0.154 mmol per kilogram of body weight), intermediate-dose (0.097 mmol/kg), or low-dose (0.047 mmol/kg) group. Two readers evaluated resulting images for arterial definition, venous contamination, and arterial stenosis. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were evaluated at six consistent sites. Statistical analysis was performed with the Kruskal-Wallis, Wilcoxon signed rank, and analysis of variance tests and the kappa coefficient. RESULTS: Readers 1 and 2 scored vascular definition as excellent or sufficient for diagnosis in 1311 of 1360 segments and in 1313 of 1360 segments in the high-dose group (kappa = 0.73), in 1321 of 1354 and in 1319 of 1354 segments in the intermediate-dose group (kappa = 0.77), and in 1322 of 1350 and in 1320 of 1350 segments in the low-dose group (kappa= 0.66), respectively. Arterial occlusive disease was detected by reader 1 in 52, 27, and 98 segments in the high-, intermediate-, and low-dose groups, respectively. Arterial occlusive disease was detected by reader 2 in 48, 25, and 100 segments in high-, intermediate-, and low-dose groups, respectively. No significant difference existed among the three groups regarding arterial definition scores (reader 1, P = .21; reader 2, P = .25) and venous contamination scores (reader 1, P = .38; reader 2, P = .35). SNRs and CNRs were lower in the low-dose group (P < .01). CONCLUSION: At 3.0 T, high-spatial-resolution MR angiography of the supraaortic arteries can be performed with contrast agent doses as low as 0.047 mmol/kg, without compromising image quality, acquisition speed, or spatial resolution. SUPPLEMENTAL MATERIAL: http://radiology.rsnajnls.org/cgi/content/full/249/3/980/DC1http://radiology.rsnajnls.org/cgi/content/full/249/3/980/DC2.

High-spatial-resolution lower extremity MR angiography at 3.0 T: contrast agent dose comparison study.

PURPOSE: To determine whether contrast material dose reduction at 3.0 T allows preserved image quality for high-spatial-resolution magnetic resonance (MR) angiography of the lower extremities. MATERIALS AND METHODS: Forty-five consecutive patients (27 men, 18 women; mean age, 64 years) underwent contrast material-enhanced MR angiography of the lower extremities at 3.0 T. A waiver of informed consent was granted by the institutional review board. Sixteen patients received high-dose (approximately 0.3 mmol/kg), 15 received intermediate-dose (approximately 0.2 mmol/kg), and 14 received low-dose (approximately 0.1 mmol/kg) gadopentetate dimeglumine during a three-station, dual-injection examination. For scoring purposes, the arterial system from the celiac trunk to the plantar arteries was divided into 34 segments. The images were retrospectively and independently evaluated by two specialized radiologists who were blinded to the patient dose groups. All studies were assessed for overall image quality and the degree of contaminating venous enhancement. Each arterial segment was scored for the quality of vessel definition, the severity of stenoses, and the presence of collateral vessels. RESULTS: More than 99% of arterial segments were found to be of diagnostic image quality by both readers in all dose groups. Generalized estimating equation analysis showed a significant difference among the three groups with regard to vessel definition (P = .019). No significant difference was found between the high- and intermediate-dose groups; however, the low-dose group had significantly better vessel definition compared with the high-dose (P = .034) and intermediate-dose (P = .015) groups. There was no significant difference among the groups in visualization of collateral vessels. Venous contamination was seen less frequently in the low-dose group, but the difference did not achieve significance. CONCLUSION: The study showed that, compared with widely used dose strategies at 1.5 T, the contrast agent dose for 3.0-T lower extremity MR angiography can be reduced multifold without compromising image quality.

Noncontrast 3D steady state free precession magnetic resonance angiography of the thoracic central veins using nonselective radiofrequency excitation over a large field of view: initial experience.

PURPOSE: To evaluate the feasibility of three-dimensional (3D) steady state free precession (SSFP) magnetic resonance angiography (MRA) using nonselective radiofrequency excitation for the assessment of thoracic central veins. MATERIALS AND METHODS: Thirty consecutive patients (17 males, 13 females, age range 22-76) with various cardiac and thoracic vascular diseases underwent free-breathing electrocardiogram-gated noncontrast SSFP MRA and conventional high-resolution 3D contrast-enhanced (CE) MRA of the thorax at 1.5 T. Two readers evaluated both datasets for findings: venous visibility and sharpness (from 0, not visualized to 3, excellent definition); artifacts; signal-to-noise ratio (SNR); and contrast-to-noise ratio (CNR) in 8 venous segments including superior vena cava (SVC), supra-diaphragmatic inferior vena cava, bilateral brachiocephalic, proximal subclavian, and lower internal jugular veins. Statistical analysis was performed using Wilcoxon test for overall image quality and vessel visibility, t test for SNR and CNR analysis, and kappa coefficient for inter-observer variability. RESULTS: 3D SSFP and CE-MRA were successfully performed in all patients. Scan time for SSFP MRA ranged from 5 to 10 minutes (mean +/- standard deviation, 7 +/- 2 minutes). Reader 1 (2) graded the overall image quality as excellent and good on SSFP MRA in 23 (25) and 7 (5) patients, and on CE-MRA in 22 (23) and 8 (9) patients, respectively. On SSFP MRA, readers 1 and 2 graded 234 (97.5%) and 233 (97.1%) venous segments with diagnostic definition (grades 2 and 3) (kappa = 0.69), respectively. On conventional CE-MRA, readers 1 and 2 graded 231 (96.3%) and 232 (96.7%) venous segments with diagnostic definition (grades 2 and 3) (kappa = 0.68), respectively. Segmental visibility and sharpness were higher for lower internal jugular veins on CE-MRA for each reader (P < 0.001). No significant difference existed for venous visibility and sharpness scores for other venous segments between the 2 techniques for both readers (P > 0.05). SNR and CNR values were lower for internal jugular veins on SSFP MRA (P < 0.001). No significant difference existed between SNR and CNR values for the other venous segments on SSFP and CE-MRA (P > 0.05 for all). The 2 readers demonstrated patent SVC Glenn shunt to main pulmonary artery (n = 3), patent extra cardiac Fontan shunt from inferior vena cava to pulmonary artery confluence (n = 2), and dilatation and thrombosis of SVC (n = 1) and right brachiocephalic vein (n = 1) on both datasets. CONCLUSION: Free breathing navigator-gated noncontrast 3D SSFP MRA with nonselective radiofrequency excitation provides high image quality and sufficient SNR and CNR for confident evaluation of thoracic central veins.

Hypervascular thyroid nodules on time-resolved MR angiography at 3 T: radiologic-pathologic correlation.

OBJECTIVE: Detection of a thyroid nodule, either incidental or as a result of related symptomatology, is an extremely common event, often inducing considerable uncertainty regarding the requirement for and best means of further investigation. Whereas tissue sampling represents the sole means of true characterization of these lesions, a number of imaging characteristics have been suggested as potential indicators of the presence of malignancy. The potential value of time-resolved MR angiography, whereby a minimal dose of i.v. contrast agent is dynamically depicted during the first pass of the bolus through the various compartments of circulation, has recently been realized, particularly so with regard to supraaortic angiography. However, it is not uncommon during such temporal imaging to identify focal hyperenhancing thyroid nodules, the significance of which has not previously been described in the literature. We describe the frequency of occurrence and potential significance of this finding, using pathologic correlation where available. CONCLUSION: The prevalence of malignancy in incidentally detected focal hyperenhancing thyroid parenchymal nodules during time-resolved MR angiography is significant, representing 8.3% (1/12) of patients for whom cytologic correlation was available. Further investigation is certainly warranted when encountering such a lesion in clinical practice, particularly because it appears as though time-resolved MR angiography is of no value in the pathologic discrimination of such incidentally identified lesions.

Duodenal abnormalities at MR small-bowel follow-through.

OBJECTIVE: The cross-sectional characterization of duodenal abnormalities is plagued with inadequacy, a reflection of the meandering course of this segment of the bowel. We consider the imaging appearance of such abnormalities at MRI small-bowel follow-through, illustrating the typical manifestations of each pathologically confirmed condition. CONCLUSION: MRI small-bowel follow-through allows confident duodenal evaluation because of a combination of sufficient luminal distention and multiplanar versatility. Diseases of the duodenum may have a variety of manifestations at MRI small-bowel follow-through, the knowledge of which may aid in confident noninvasive patient diagnosis.

MR enterography of small-bowel lymphoma: potential for suggestion of histologic subtype and the presence of underlying celiac disease.

OBJECTIVE: The objective of our study was to evaluate the morphologic appearances of small-bowel lymphoma using MR enterography to identify key morphologic traits capable of providing an association between imaging manifestations and likely histologic diagnosis. MATERIALS AND METHODS: Over a 54-month period, 10 patients with subsequently confirmed small-bowel lymphoma were imaged using a standardized MR enterography technique. Retrospective chart review was performed to detect associated disease processes, such as celiac disease. The morphologic characteristics of each segment with lymphomatous involvement were evaluated with respect to tumor location, tumor size, mural characteristics, fold features, loop dilatation, luminal stricturing, mesenteric or antimesenteric distribution, mesenteric involvement, and signal intensity. RESULTS: Nineteen distinct segments of lymphomatous involvement were identified in 10 patients, and underlying celiac disease was confirmed in six of the 10 patients. This patient group comprised 10 patients with non-Hodgkin's lymphoma (NHL) of various subtypes. No cases of Hodgkin's lymphoma were encountered. Analysis revealed celiac NHL enteropathy to have a tendency toward localization to a single, long (> 10 cm), smooth continuous bowel segment, often with aneurysmal loop dilatation, in the absence of a distinct mesenteric or antimesenteric distribution. Luminal stricturing was encountered in cases of low-grade lymphoma, whereas mesenteric fat infiltration represented a characteristic of high-grade disease. CONCLUSION: We describe the characteristics of small-bowel lymphoma on MR enterography, identifying a number of key features that may help the interpreting radiologist in suggesting the underlying histologic subtype and whether the presence of underlying celiac disease is likely.

Retroperitoneal fibrosis: a review of clinical features and imaging findings.

OBJECTIVE: Retroperitoneal fibrosis is a rare collagen vascular disorder of unclear cause. Both benign and malignant associations have been described, rendering differentiation of these entities of paramount importance because sinister pathology alters the diagnosis. Thus, a high level of diligence is required in the investigation of this condition, particularly in patients with concomitant systemic conditions. CONCLUSION: Familiarity with the realm of imaging manifestations of retroperitoneal fibrosis is vital to ensure correct diagnosis and optimal treatment.

MR angiography of lower extremities at 3 T: presurgical planning of fibular free flap transfer for facial reconstruction.

OBJECTIVE: The purpose of our study was to evaluate the use of preoperative MR angiography of the lower extremities at 3 T in candidates for fibular free flap harvesting, identifying atherosclerotic occlusive disease and congenital anomalies in this population. Our intention was to document the influence of the imaging findings on the surgical approach used. MATERIALS AND METHODS: Twenty-nine consecutive adult patients with facial abnormalities necessitating mandibular resection with subsequent osteocutaneous mandibular reconstruction who underwent preoperative MR angiography at 3 T were retrospectively reviewed. Images were evaluated by two observers with regard to image quality and visualization of arterial segments; severity of stenosis; and presence of noise, artifact, or venous contamination. The popliteal artery branching pattern present was also classified. The facial and reconstructive surgeon involved indicated whether the MR angiographic appearances influenced the decision regarding the side or location from which the flap was harvested or the flap design. RESULTS: Arterial segments were visualized with good or excellent image quality in 722 of 725 segments for observer 1 and 721 segments for observer 2. The kappa coefficient indicated good interobserver agreement (kappa = 0.78) with regard to quality of arterial segment depiction and scoring of stenoocclusive disease (kappa = 0.64). No segments had venous contamination, noise, or artifact of a degree sufficient to compromise diagnostic interpretation. Imaging influenced the surgical approach in 16 (55.2%) of 29 patients. CONCLUSION: Trifurcation vessel imaging should be a prerequisite to fibular free flap harvesting. High-spatial-resolution MR angiography at 3 T represents a desirable alternative to other invasive or cross-sectional imaging techniques in this regard.

Does dual-energy CT of lower-extremity tendons incur penalties in patient radiation exposure or reduced multiplanar reconstruction image quality?

OBJECTIVE: The purposes of this study were to evaluate the quality and radiation exposure of data acquired with dual-energy CT compared with single-energy MDCT in the depiction of lower-extremity tendons and to assess whether a dual-energy CT voltage exists at which the quality of tendon depiction is optimal. SUBJECTS AND METHODS: Eleven healthy volunteers and seven clinically referred patients (10 men, eight women; mean age, 43.1 years; range, 20-71 years) underwent conventional single-energy CT and dual-energy CT examinations of both lower extremities with a dual-source CT scanner. Dual-energy reconstructions were made at combined tube voltages approximating 86, 98, 110, 122, and 134 kVp. Quantitative and qualitative analyses were performed on six tendons in each lower extremity, and the findings were compared with single-energy CT findings. The radiation dose involved was recorded in each case. RESULTS: A trend toward increasing tendon attenuation was observed with increasing reconstructed tube voltage. The group of single-energy CT reconstructions proved significantly superior to each of the dual-energy CT reconstructions with regard to signal-to-noise ratio (F = 35.25, p < 0.0001) and contrast-to-noise ratio (F = 37.19, p < 0.0001), although interobserver agreement in subjective ranking was poor. Dual-energy CT had a significantly higher radiation dose (p < 0.05) than single-energy CT. CONCLUSION: Dual-energy CT of lower-extremity tendons, irrespective of the reconstruction tube voltage chosen, yields multiplanar reformations inferior to those of single-energy CT with regard to signal-to-noise and contrast-to-noise ratios while involving significantly escalated patient exposure to ionizing radiation. Whether the tissue-differentiating promise of dual-energy CT is realized in future studies and warrants such concessions remains to be seen.

MRI small-bowel follow-through: prone versus supine patient positioning for best small-bowel distention and lesion detection.

OBJECTIVE: The purpose of this study was to assess whether prone or supine imaging provides superior small-bowel loop distention during MRI small-bowel follow-through examinations and whether either position is better with regard to lesion detection and evaluation. SUBJECTS AND METHODS: Forty consecutively enrolled clinically referred patients with known or suspected small-bowel abnormalities prospectively underwent 62 MRI small-bowel follow-through examinations in both the prone and the supine positions. Images were blindly and independently reviewed by two observers. Each small-bowel segment was assessed with a 3-point scoring system, and differences in bowel distention in the prone and supine positions were evaluated with a paired Wilcoxon's test. Differences between rates of lesion detection and characterization (e.g., ulceration, stricturing) were analyzed with a paired Student's t test. Interobserver agreement was estimated with the kappa coefficient. RESULTS: In both normal and diseased small bowel, the prone position had statistically significantly higher distention scores than did the supine position (p < 0.05) with a high level of interobserver agreement. This finding, however, did not translate into improved lesion detection or characterization (p > 0.05). CONCLUSION: Although use of the prone position results in superior small-bowel distention during MRI small-bowel follow-through, both the prone and supine positions are equal in terms of lesion detection and feature visualization.

MR imaging of the thoracic aorta.

MR imaging has been incorporated into the diagnostic algorithm for suspected thoracic aortic pathology, challenging CT and invasive catheter angiography as investigations of choice. Techniques, including spin echo, 3-D steady-state free precession, cardiac cine imaging, phase-contrast flow quantification, and high-resolution contrast-enhanced magnetic resonance angiography, are poised to trump other single competitive modalities. The proliferation of 3-tesla systems has advanced the performance of magnetic resonance, aided by parallel imaging techniques, multiarray surface coils, and powerful gradient coils. This article considers the current status of MR imaging in evaluation of the thoracic aorta, with reference to common clinical indications in clinical practice.

Time-resolved MR angiography of the thorax.

Time-resolved magnetic resonance angiography (TR-MRA) has received considerable attention recently owing to its ability to provide a dynamic complement to otherwise "static" high-resolution 3-D contrast-enhanced MRA for a variety of clinical indications. Steady technologic advances, including ultrafast pulse sequences, phased multiarray surface coils, parallel data acquisition techniques, and the widespread availability of high-field magnetic resonance systems, have enhanced the clinical usefulness of TR-MRA. This article considers the current role of TR-MRA in thoracic imaging, illustrating many of its clinical applications, and potential future of this recent approach to noninvasive dynamic vascular evaluation.