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.

Diagnosis and management of upper extremity deep-vein thrombosis in adults.

Upper extremity deep-vein thrombosis (UEDVT) is common and can cause important complications, including pulmonary embolism and post-thrombotic syndrome. An increase in the use of central venous catheters, particularly peripherally inserted central catheters has been associated with an increasing rate of disease. Accurate diagnosis is essential to guide management, but there are limitations to the available evidence for available diagnostic tests. Anticoagulation is the mainstay of therapy, but interventional treatments may be considered in select situations. The risk of UEDVT may be reduced by more careful selection of patients who receive central venous catheters and by use of smaller catheters. Herein we review the diagnosis, management and prevention of UEDVT. Due to paucity of research, some principles are drawn from studies of lower extremity DVT. We present a practical approach to diagnosing the patient with suspected deep-vein thrombosis of the upper extremity.

Non-invasive detection of vulnerable coronary plaque.

Critical coronary stenoses have been shown to contribute to only a minority of acute coronary syndromes and sudden cardiac death. Autopsy studies have identified a subgroup of high-risk patients with disrupted vulnerable plaque and modest stenosis. Consequently, a clinical need exists to develop methods to identify these plaques prospectively before disruption and clinical expression of disease. Recent advances in invasive and non-invasive imaging techniques have shown the potential to identify these high-risk plaques. Non-invasive imaging with magnetic resonance imaging, computed tomography and positron emission tomography holds the potential to differentiate between low- and high-risk plaques. There have been significant technological advances in non-invasive imaging modalities, and the aim is to achieve a diagnostic sensitivity for these technologies similar to that of the invasive modalities. Molecular imaging with the use of novel targeted nanoparticles may help in detecting high-risk plaques that will ultimately cause acute myocardial infarction. Moreover, nanoparticle-based imaging may even provide non-invasive treatments for these plaques. However, at present none of these imaging modalities are able to detect vulnerable plaque nor have they been shown to definitively predict outcome. Further trials are needed to provide more information regarding the natural history of high-risk but non-flow-limiting plaque to establish patient specific targeted therapy and to refine plaque stabilizing strategies in the future.

Two-dimensional and Doppler echocardiography reliably predict severe pulmonary regurgitation as quantified by cardiac magnetic resonance.

BACKGROUND: The grading of pulmonary regurgitation (PR) severity by two-dimensional (2D) and Doppler echocardiography is not standardized. Cardiovascular magnetic resonance imaging is the clinical gold standard for PR quantification. The purpose of this study was to determine the best 2D and Doppler echocardiographic predictors of severe PR. METHODS: Thirty-six patients with tetralogy of Fallot or pulmonary valve stenosis with prior pulmonary valvuloplasty or transannular or subannular patch repair underwent 2D and Doppler echocardiography and cardiovascular magnetic resonance. Two-dimensional and Doppler echocardiographic measurements used to predict severe PR included diastolic flow reversal in the main or branch pulmonary arteries, PR jet width > or = 50% of the pulmonary annulus, PR pressure half-time < 100 ms, and PR index < 0.77. RESULTS: With the exception of PR index, all indices were significant independent predictors of severe PR. The best univariate predictor of severe PR was branch pulmonary artery diastolic flow reversal. CONCLUSION: Two-dimensional and Doppler echocardiography reliably identified severe PR in this cohort.

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.

Normal small bowel wall characteristics on MR enterography.

PURPOSE: To assess the normal small bowel parameters, namely bowel diameter, bowel wall thickness, number of folds (valvulae connivientes) per 2.5 cm (in.), fold thickness and interfold distance per small bowel segment (duodenum, jejunum, proximal ileum, distal ileum and terminal ileum) on MR enterography. MATERIALS AND METHODS: Between September 2003 and January 2008, 280 MR enterography examinations were performed for investigation of known or suspected small bowel pathology. 120 of these examinations were normal. Sixty-five (m=29, f=36, mean age=34 years, range=17-73 years) of 120 examinations without a prior small bowel diagnosis, with no prior or subsequent abnormal radiology or endoscopy examinations, no prior small bowel surgery and with a minimum 3 years follow-up demonstrating normality were retrospectively evaluated for the described small bowel parameters. RESULTS: We found the mean diameter of the duodenum to be 24.8mm (S.D.=4.5mm), jejunum to be 24.5mm (S.D.=4.2mm), proximal ileum to be 19.5mm (S.D.=3.6mm), distal ileum to be 18.9 mm (S.D.=4.2mm) and terminal ileum to be 18.7 mm (S.D.=3.6mm). The number of folds per 2.5 cm varied from 4.6 in the jejunum to 1.5 in the terminal ileum. The fold thickness varied from 2.1mm in the duodenum to 1.8mm in the terminal ileum. The small bowel parameters gradually decreased in size from the duodenum to the smallest measurements which were in the terminal ileum. The bowel wall is similar in size throughout the small bowel measuring 1.5+/-0.5mm. CONCLUSION: These results provide the mean, range of normality and standard deviation of the small bowel parameters per segment on the current population on MR enterography. From our experience, knowledge of these parameters is extremely helpful and essential in the everyday assessment of MR enterography studies.

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.

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.

Ultra-low-dose, time-resolved contrast-enhanced magnetic resonance angiography of the carotid arteries at 3.0 tesla.

PURPOSE: To determine whether time-resolved magnetic resonance angiography (TR-MRA) with ultra-low-dose gadolinium chelate (1.5-3.0 mL) can reliably detect or rule out hemodynamically significant disease in the carotid-vertebral artery territory. MATERIALS AND METHODS: Hundred consecutive patients (62 women, 38 men, mean age = 56.6 years) underwent both TR-MRA and standard high-resolution contrast-enhanced magnetic resonance angiography (CE-MRA), having been randomized to 1 of 2 groups; group A receiving a contrast dose of 1.5 mL for TR-MRA and group B receiving 3.0 mL. For scoring purposes the arterial system was divided into 21 segments. All TR-MRA and CE-MRA studies were blindly assessed by 2 radiologists for overall image quality, segmental arterial visualization, grading of arterial stenosis/occlusion, and incidence and severity of artifact. TR-MRA findings were directly compared with those of the corresponding CE-MRA examinations. RESULTS: Group A TR-MRA studies were of significantly inferior overall image quality compared with those of the corresponding CE-MRA examinations (P = 0.01 for both observers). In group B, overall image quality was similar for TR-MRA and single-phase CE-MRA examinations. On a segmental basis, a higher number of "insufficient quality" segments were identified in group A TR-MRA studies than in group B. A similar reduction in the incidence of artifacts was observed for group B relative to group A TR-MRA studies. Both groups A and B TR-MRA studies were of high specificity, negative predictive values, and accuracy (>97%). CONCLUSION: Ultra-low dose TR-MRA may be performed with 3 mL of gadolinium chelate with preservation of overall image quality and arterial segmental visualization relative to single phase CE-MRA, whereas a 1.5 mL contrast dose is associated with more suboptimal studies. Nonetheless, even at doses as low as 1.5 mL, TR-MRA can exclude arterial stenosis or occlusion.

Adult Tetralogy of Fallot: quantitative assessment of pulmonary perfusion with time-resolved three dimensional magnetic resonance angiography.

PURPOSE: To determine the potential role of dynamic temporally resolved three dimensional (3D) contrast-enhanced magnetic resonance angiography (MRA) for quantitative evaluation of pulmonary perfusion in adult patients with surgically treated Tetralogy of Fallot (ToF). MATERIALS AND METHODS: Institutional review board approval and written informed consent were obtained for this Health Insurance Portability and Accountability Act-compliant study. Thirty consecutive patients with surgically repaired ToF and 30 age-matched controls underwent breath-hold 3D time-resolved MRA (TR-MRA) and single-phase high-resolution 3D MRA of the thorax at 1.5 T. Two readers evaluated both datasets for image quality and findings. On TR-MRA datasets, regions-of-interest were placed over main pulmonary artery and lung fields obtaining signal intensity time curves. Using analytic software, time-to-peak (TTP), mean transit time (MTT), maximal signal intensity (MSI), maximum upslope of the curve (MUS), pulmonary blood volume (PBV), and pulmonary blood flow (PBF) were calculated. Pulmonary radionuclide scintigraphy was available for a subgroup of patients with ToF (n = 12). RESULTS: For ToF patients with unilateral pulmonary artery (PA) stenosis, TTP, and MTT were significantly longer, and MSI, MUS, PBV, and PBF were significantly lower in the ipsilateral lung compared with control subjects (P < 0.001 for all). There was no significant difference in TTP, MTT, MSI, MUS, PBV, and PBF between ToF patients without postsurgical stenotic residua and control subjects (P > 0.05 for all), nor between the mentioned perfusion indices for the contralateral lung in ToF patients with unilateral PA stenosis and control subjects (P > 0.05 for all). In ToF, patient with unilateral PA stenosis, analysis of contralateral-to-ipsilateral lung perfusion ratios on radionuclide scintigraphy and TR-MRA revealed significant correlation (r = 0.96). Bland-Altman plot showed a mean difference of 2.2% between the measured ratios (limits of agreement; -7.6%-12.0%). CONCLUSION: Time-resolved 3D contrast-enhanced MRA has potential for noninvasive and quantitative assessment of altered patterns of pulmonary perfusion in adult ToF, and may be a reliable technique for evaluation of postsurgical residua in these patients.

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.

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.

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.

Current status of 3-T cardiovascular magnetic resonance imaging.

Continued advances in radiofrequency hardware and tailored software have, in recent times, greatly increased the power and performance of magnetic resonance imaging for noninvasive evaluation of cardiovascular diseases. Magnetic resonance imaging can uniquely be manipulated to trade temporal resolution and spatial resolution against each other, depending on whether detailed structural or functional information is required. However, to date, a number of cardiovascular magnetic resonance applications have been somewhat limited due to signal-to-noise ratio constraints, reflecting the narrow imaging window imposed by physiological cardiac motion. By increasing the operating field strength from 1.5 to 3 T, it is possible (in principle) to double the signal-to-noise ratio, which in turn may be "traded" for improvements in spatial resolution, coverage, or imaging speed. In this context, the development of parallel imaging has set the stage for impressive performance improvements in contrast-enhanced magnetic resonance angiography at 3 T. Indeed, one could argue that without parallel acquisition, the bang for the buck in going from 1.5 to 3 T would be limited. In this paper, we discuss the current status of 3-T magnetic resonance imaging for cardiovascular imaging, considering the relative gains and limitations relative to 1.5 T.

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.

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.

Anatomy, pathology, imaging and intervention of the iliopsoas muscle revisited.

The apparent incidence of iliopsoas muscle abnormalities is currently rapidly increasing secondary to the increased number of immuno-compromised patients, malignancies, chemotherapy, immunotherapy, multi-systemic disease and the wide availability of cross-sectional imaging. Disease of the iliopsoas compartment can present with non-specific or indolent clinical features, particularly where normal immune responses are attenuated. Delay in diagnosis can lead to inappropriate initial treatment and, in some cases, serious complications. Wider availability and application of modern cross-sectional imaging offers rapid, confident diagnosis. An understanding of iliopsoas compartment anatomy and pathways of disease spread are essential to recognising these clinically important conditions. We review the anatomy, clinical presentation and common imaging findings of iliopsoas disease as it presents through the emergency room.

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.