Frequency of anterolateral ligament tears and ramp lesions in patients with anterior cruciate ligament tears and associated injuries indicative for these lesions-a retrospective MRI analysis.

OBJECTIVES: To assess the frequency of anterolateral ligament (ALL) tears and ramp lesions (RL) detected with MRI in patients with anterior cruciate ligament (ACL) tears and to describe associated injuries indicative for these lesions. METHODS: In this retrospective study, 164 patients with surgically verified ACL tears were included. Preoperative MRI scans were reviewed for ALL tears and different types of RL. All coexisting meniscal tears, tears of the medial (MCL) and lateral collateral band (LCL), and posterior-medial tibial bone marrow edema (BME) were recorded. The frequency of ALL tears and RL was assessed and coexisting injuries were correlated using Pearson's chi-square test. A p < 0.05 was defined as statistically significant. In cases of multiple testing, Bonferroni's correction was applied. RESULTS: ALL tears and RL combined were detected in 28 patients (17.1%), ALL tears in 48 patients (29.3%), and RL in 54 patients (32.9%) which were significantly associated to each other. ALL tears were significantly associated with tears of the posterior horn of the lateral meniscus (PHLM), BME, and with tears of the LCL and MCL. RL were significantly associated with tears of the posterior horn of the medial (PHMM) and PHLM, with BME, and with tears of the LCL. CONCLUSIONS: ACL tears are associated with RL or ALL tears in about one-third of cases and with both lesions combined in about one-fifth of cases. ALL tears and RL are significantly associated with additional posttraumatic injuries, which can thus be indicative of these lesions. KEY POINTS: • ACL tears were associated with ramp lesions or ALL tears in about one-third of the cases. • Ramp lesions and ALL tears were significantly associated with each other, tear in the PHLM, tear in the LCL, and BME. • ALL tears were more frequently associated with instable classified ramp lesion type 4b and type 5.

Food intolerance/malabsorption may occur in rare diseases.

Sugars including lactose and fructose, or proteins (gluten), or biogenic amines (histamine), and combinations thereof may cause food intolerance/malabsorption. However, in usually asymptomatic patients with rare diseases, who present with functional, non-specific, non-allergic gastrointestinal (GI) complaints the etiologic factors of food intolerance/malabsorption need to be evaluated. We summarize patients with rare diseases, such as primary epiploic appendagitis, beta-thalassemias minor, Gullo syndrome and anomaly of the inferior vena cava, who presented functional, non-specific, non-allergic GI complaints. As conclusion, these GI symptoms in patients with otherwise asymptomatic, rare diseases were due to fructose malabsorption, histamine-, lactose intolerance and Helicobacter pylori (H.p.) infection. A registered and experienced dietician was employed to design an individually-tailored diet which ensured effective treatments and H.p. infection was accordingly eradicated.

Heart rate-reducing therapy with add-on ivabradine and bisoprolol before coronary computed tomographic angiography in a fast-track ambulatory setting.

Objective This study was performed to determine whether add-on oral ivabradine in patients treated with beta blockers 1 hour before coronary computed tomographic angiography (CCTA) is effective in lowering the heart rate and thus improving CCTA quality. Methods In this single-center cohort study, the data of 294 patients referred for ambulant CCTA were retrospectively screened. Patients with an initial heart rate of ≥75 bpm (n = 112) were pretreated with either a combination of bisoprolol and ivabradine or with bisoprolol alone. Results During the scan, there was no difference in heart rate between the two groups Likewise, there was no significant difference in additionally administered intravenous bradycardic agents, the number of motion artifacts, or the radiation dose. Both drug regimens were tolerated well. Conclusion Additive oral ivabradine 1 hour before CCTA does not result in a further reduction of the heart rate. Consequently, neither movement artifacts nor radiation dose can be reduced. Therefore, pretreatment with ivabradine does not seem reasonably appropriate in an outpatient clinical setting with short patient contact.

3 Tesla breast MR imaging as a problem-solving tool: Diagnostic performance and incidental lesions.

PURPOSE: To investigate the diagnostic performance and incidental lesion yield of 3T breast MRI if used as a problem-solving tool. METHODS: This retrospective, IRB-approved, cross-sectional, single-center study comprised 302 consecutive women (mean: 50±12 years; range: 20-79 years) who were undergoing 3T breast MRI between 03/2013-12/2014 for further workup of conventional and clinical breast findings. Images were read by experienced, board-certified radiologists. The reference standard was histopathology or follow-up ≥ two years. Sensitivity, specificity, PPV, and NPV were calculated. Results were stratified by conventional and clinical breast findings. RESULTS: The reference standard revealed 53 true-positive, 243 true-negative, 20 false-positive, and two false-negative breast MRI findings, resulting in a sensitivity, specificity, PPV, and NPV of 96.4% (53/55), 92.4% (243/263), 72.6% (53/73), and 99.2% (243/245), respectively. In 5.3% (16/302) of all patients, incidental MRI lesions classified BI-RADS 3-5 were detected, 37.5% (6/16) of which were malignant. Breast composition and the imaging findings that had led to referral had no significant influence on the diagnostic performance of breast MR imaging (p>0.05). CONCLUSION: 3T breast MRI yields excellent diagnostic results if used as a problem-solving tool independent of referral reasons. The number of suspicious incidental lesions detected by MRI is low, but is associated with a substantial malignancy rate.

First pass dual input volume CT-perfusion of lung lesions: The influence of the CT- value range settings on the perfusion values of benign and malignant entities.

OBJECTIVE: To assess the influence of the lower threshold for segmentation of the volume of interest on the perfusion values in first-pass dual input volume CT-perfusion of lung lesions. MATERIALS AND METHODS: Dual input maximum slope volume CT-perfusion was performed in 48 patients (mean age±standard deviation [SD], 68±10years; range, 46-87 years) who underwent subsequent CT-guided biopsy to evaluate a lung lesion. Using commercial perfusion software, a lower and upper threshold was set for determination of the CT-value range, which again determined the volume of interest for perfusion calculation. The pulmonary arterial flow (PAF), bronchial arterial flow (BAF), and perfusion index (PI; PAF/(PAF+BAF)) were calculated at following pre contrast CT value range settings: -80 to 150HU (setting 1), -200 to 150HU (setting 2), -300 to 150HU (setting 3), and -500 to 150HU (setting 4). Perfusion parameters were compared between benign (n, 15) and malignant (n, 33) lesions for each setting. Intraobserver- and interobserver reliability were calculated for setting 4. RESULTS: Median PAF was significantly higher in malignant lesions than in benign lesions for all settings (53-96 versus 29-62mL/min/100mL, P<0.05). There was no significant difference in BAF between malignant and benign lesions. Median PAF of all lesions was significantly influenced by the CT value range setting (P<0.05), whereas the values increased from setting 1 to 4. Intraobserver analysis as well as interobserver analysis of PAF at setting 4 showed excellent reliability (Cronbach's alpha 0.98 and 0.95, respectively, P<0.01). CONCLUSION: PAF derived from first-pass dual-input maximum slope volume CT perfusion is statistically significantly higher in malignant than in benign lesion, whereas the measurements are influenced by the lower threshold of the CT value range setting. This has to be considered when using cutoff values provided in the literature for differentiation between benign and malignant lung lesions.

Breast MRI used as a problem-solving tool reliably excludes malignancy.

PURPOSE: To evaluate the diagnostic performance of breast MRI if used as a problem-solving tool in BI-RADS 0 cases. MATERIAL AND METHODS: In this IRB-approved, single-center study, 687 women underwent high-resolution-3D, dynamic contrast-enhanced breast magnetic resonance imaging (MRI) between January 2012 and December 2012. Of these, we analyzed 111 consecutive patients (mean age, 51 ± 12 years; range, 20-83 years) categorized as BI-RADS 0. Breast MRI findings were stratified by clinical presentations, conventional imaging findings, and breast density. MRI results were compared to the reference standard, defined as histopathology or an imaging follow-up of at least 1 year. RESULTS: One hundred eleven patients with BI-RADS 0 conventional imaging findings revealed 30 (27%) mammographic masses, 57 (51.4%) mammographic architectural distortions, five (4.5%) mammographic microcalcifications, 17 (15.3%) ultrasound-only findings, and two palpable findings without imaging correlates. There were 15 true-positive, 85 true-negative, 11 false-positive, and zero false-negative breast MRI findings, resulting in a sensitivity, specificity, PPV, and NPV of 100% (15/15), 88.5% (85/96), 57.7% (15/26), and 100% (85/85), respectively. Breast density and reasons for referral had no significant influence on the diagnostic performance of breast MRI (p>0.05). CONCLUSION: Breast MRI reliably excludes malignancy in conventional BI-RADS 0 cases resulting in a NPV of 100% (85/85) and a PPV of 57.7% (15/26).

MR arthrography of the shoulder: do we need local anesthesia?

PURPOSE: To assess pain intensity with and without subcutaneous local anesthesia prior to intraarticular administration of contrast medium for magnetic resonance arthrography (MRa) of the shoulder. MATERIALS AND METHODS: This single-center study was conducted after an IRB waiver of authorization, between January 2010 and December 2012. All patients provided written, informed consent for the procedure. Our prospectively populated institutional database was searched, based on our inclusion criteria. There were 249 outpatients (178 men and 71 women; mean age, 44.4 years ± 14.6; range, 15-79) who underwent MRa and were enrolled in this study. Patients were excluded if they had received surgery of the shoulder before MRa, had undergone repeated MRa of the same shoulder, and/or had undergone MRa of both shoulders on the same day. Patients were randomly assigned into one of three groups. Patients in group A (n=61) received skin infiltration with local anesthesia. Patients in control group B (n=92) and group C (n=96) did not receive local anesthesia. Pain levels were immediately assessed after the injection for MRa using a horizontal visual analog scale (VAS) that ranged from 0 to 10. To compare the pain scores of the three groups for male and female patients, a two-way analysis of variance was used. A p-value equal to or less than 0.05 was considered to indicate a significant result. RESULTS: Patients who received local anesthesia (group A) showed a mean pain level on the VAS of 2.6 ± 2.3. In patients who did not receive local anesthetics (groups B and C), a mean pain level on the VAS of 2.6 ± 2.2 and 2.7 ± 2.4 were detected, respectively. Between the three groups, no statistically significant difference in pain intensity was detected (p=.960). There were significant differences in subjective pain perception between men and women (p=.009). Moreover, the sex difference in all three groups was equal (p=.934). CONCLUSION: Local anesthesia is not required to lower a patient's pain intensity when applying intra-articular contrast media for MR arthrography of the shoulder. This could result in reduced costs and a reduced risk of adverse reactions, without an impact on patient comfort.

Rate of malignancy in MRI-detected probably benign (BI-RADS 3) lesions.

OBJECTIVE: The purpose of this study was to evaluate the malignancy rate in MRI-detected probably benign (BI-RADS 3) lesions in women without a history of breast cancer. MATERIALS AND METHODS: In this study, 1265 patients underwent breast MRI during a 7-year period. One hundred and eight (8.5%) patients with a nonpalpable breast lesion classified as BI-RADS 3 at MRI and with a needle biopsy or adequate follow-up of at least 24 months were included. Statistical analysis included calculation of the negative predictive value with its 95% CI. RESULTS: Of 108 lesions, 107 (99.1%) were correctly assessed as probably benign, resulting in a negative predictive value of 99.1% (95% CI, 94.99-99.98%). Histopathology was requested by the patient or referring physician in 44 patients. Of these, 43 (39.8%) lesions were classified as benign and one (0.9%) as malignant. There were no changes evident in any of the remaining 64 (59.2%) lesions during follow-up (range, 2-9 years). CONCLUSION: In MRI-detected probably benign (BI-RADS 3) lesions, the malignancy rate is low and within the accepted cancer rate for mammographically or sonographically detected BI-RADS 3 lesions. Short-term follow-up MRI at intervals of 6, 12, and 24 months in MRI BI-RADS 3 lesions remains a strong tool with which to detect suspicious lesions. Interval changes in size, morphology, or enhancement are regarded as indicative of malignancy.

Primary epiploic appendagitis and successful outpatient management.

BACKGROUND: Primary epiploic appendagitis (PEA) is a rare cause of abdominal acute or subacute complaints. Diagnosis of PEA is made with ultrasonography (US) or when computed tomography (CT) reveals a characteristic lesion. CASE REPORT: We report on two patients with PEA. In one patient PEA was first seen with US and confirmed with contrast enhanced CT, and in the second patient CT without contrast enhancement demonstrated PEA. In both patients an outpatient recovery with conservative non-surgical treatment is described. CONCLUSIONS: Medical personnel should be aware of this rare disease, which mimics many other intra-abdominal acute and subacute conditions. A correct diagnosis of PEA with imaging procedures enables conservative and successful outpatient management avoiding unnecessary surgical intervention and additional costs.

Insights into epiploic appendagitis.

Epiploic appendagitis is a rare cause of abdominal pain. Diagnosis of epiploic appendagitis, although infrequent, is easily made with CT or ultrasonography in experienced hands. As reported in the literature, most patients with primary epiploic appendagitis are treated conservatively without surgery, with or without anti-inflammatory drugs. A small number of patients are treated with antibiotics and some patients require surgical intervention to ensure therapeutic success. Symptoms of primary epiploic appendagitis usually resolve with or without treatment within a few days. A correct diagnosis of epiploic appendagitis with imaging procedures enables conservative and successful outpatient management of the condition and avoids unnecessary surgical intervention and associated additional health-care costs. Gastroenterologists and all medical personnel should be aware of this rare disease, which mimics many other intra-abdominal acute and subacute conditions, such as diverticulitis, cholecystitis and appendicitis. This article reviews epiploic appendagitis and includes discussion of clinical findings, pathophysiology, diagnosis and therapeutic possibilities.

Multi-detector CT urography: effect of oral hydration and contrast medium volume on renal parenchymal enhancement and urinary tract opacification--a quantitative and qualitative analysis.

OBJECTIVE: To assess the effect of oral hydration and contrast-medium volume on renal enhancement and urinary tract opacification in multi-detector CT urography. METHODS: A total of 192 patients were assigned to different protocols with varying doses of contrast agent with and without oral hydration. The attenuation was measured in the renal parenchyma in the unenhanced, nephrographic and excretory phase, and in the urinary tract in excretory phase imaging, respectively. Opacification of the urinary tract was graded on volume rendered images. RESULTS: Oral hydration did not significantly alter renal parenchymal enhancement in both the nephrographic and the excretory phase (p > 0.001), but significantly decreased mean attenuation of the urinary tract in the excretory phase (p < or = 0.001), and improved continuous opacification of all ureter segments (p < 0.01). Higher volumes of contrast medium improved renal parenchymal enhancement (p < or = 0.001) and continuous opacification of the urinary tract (p < or = 0.01). CONCLUSION: Oral hydration leads to lower attenuation values in the urinary tract but improves the continuous opacification of the tract. Increase in contrast medium volume leads to higher renal parenchymal enhancement as well as to an increased continuous opacification of the urinary tract. Decrease in contrast medium volume cannot be compensated for by oral hydration in terms of parenchymal enhancement.

MDCT angiography of the pulmonary arteries: influence of body weight, body mass index, and scan length on arterial enhancement at different iodine flow rates.

OBJECTIVE: The purpose of this study was to assess whether body weight, body mass index, and scan length influence arterial enhancement during CT angiography (CTA) of the pulmonary arteries at different iodine flow rates. MATERIALS AND METHODS: CTA examinations of the pulmonary arteries performed for routine clinical care of 120 patients between March and December 2003 were retrospectively evaluated. Patients had received either 120 mL of contrast medium with an iodine concentration of 300 mg I/mL (group A) or 90 mL of contrast medium with an iodine concentration of 400 mg I/mL (group B). The iodine dose was 36 g, and the injection rate was 4 mL/s in all examinations. The iodine flow rate was 1.2 g I/s in group A and 1.6 g I/s in group B. Arterial attenuation along the z-axis was measured per patient, and the influence of body weight, body mass index, and scan length on enhancement of the pulmonary arteries in the two groups was assessed. RESULTS: In group A and in group B, body weight and body mass index correlated significantly with mean enhancement along the z-axis (r = -0.35 and -0.26 for group A and -0.48 and -0.40 for group B). Scan length showed no correlation with pulmonary attenuation. Mean pulmonary artery enhancement was significantly higher in group B with a difference of 51 H compared with group A. CONCLUSION: Pulmonary artery attenuation in CTA of the pulmonary arteries shows a small but significant correlation with body weight and body mass index independently of the iodine flow rate used. A higher iodine flow rate improves pulmonary artery enhancement.

Routine use of three-dimensional contrast-enhanced moving-table MR angiography in patients with peripheral arterial occlusive disease: comparison with selective digital subtraction angiography.

PURPOSE: To compare the diagnostic accuracy of contrast-enhanced (CE) three-dimensional (3D) moving-table magnetic resonance (MR) angiography with that of selective digital subtraction angiography (DSA) for routine clinical investigation in patients with peripheral arterial occlusive disease. METHODS: Thirty-eight patients underwent CE 3D moving-table MR angiography of the pelvic and peripheral arteries. A commercially available large-field-of-view adapter and a dedicated peripheral vascular phased-array coil were used. MR angiograms were evaluated for grade of arterial stenosis, diagnostic quality, and presence of artifacts. MR imaging results for each patient were compared with those of selective DSA. RESULTS: Two hundred and twenty-six arterial segments in 38 patients were evaluated by both selective DSA and MR angiography. No complications related to MR angiography were observed. There was agreement in stenosis classification in 204 (90.3%) segments; MR angiography overgraded 16 (7%) segments and undergraded 6 (2.7%) segments. Compared with selective DSA, MR angiography provided high sensitivity and specificity and excellent interobserver agreement for detection of severe stenosis (97% and 95%, kappa = 0.9 +/- 0.03) and moderate stenosis (96.5% and 94.3%, kappa = 0.9 +/- 0.03). CONCLUSION: Compared with selective DSA, moving-table MR angiography proved to be an accurate, noninvasive method for evaluation of peripheral arterial occlusive disease and may thus serve as an alternative to DSA in clinical routine.

Multiphasic multidetector-row CT (MDCT) in detection and staging of transitional cell carcinomas of the upper urinary tract.

The aim of this study was to evaluate the potential of multiphasic multidetector-row CT (MDCT) in the detection and staging of transitional cell carcinomas (TCC) of the upper urinary tract. We performed a retrospective chart review of 39 consecutive patients with 41 histologically verified TCC of the renal pelvis and/or the ureter. The urinary tract was examined using MDCT performing unenhanced and contrast-enhanced scans during the corticomedullary (CMP), nephrographic (NP) and pyelographic phase (PP). Tumors were staged according to the TNM classification. MDCT and histopathological findings were correlated. The attenuation of the lesions was documented in Hounsfield units (HU). In MDCT, all 41 TCC--including two multicentric TCC--were detected. TCC confined to the organ (stage 0a-II) was correctly staged in 28/29 tumors (96.6%). Stage III-IV tumors were correctly staged in 8/12 patients (66.6%). Overall, MDCT was accurate in predicting pathologic TNM stage in 36/41 upper urinary tract TCC (87.8%). There was no significant difference of mean attenuation of TCC between CMP, NP and PP (P > 0.05). MDCT with its high spatial and temporal resolution is an accurate tool for detection TCC of the upper urinary tract, with 87.8% accuracy in predicting its stage.

High-concentration contrast media in multiphasic abdominal multidetector-row computed tomography: effect of increased iodine flow rate on parenchymal and vascular enhancement.

OBJECTIVE: The purpose of this study was to assess the influence of the iodine flow rate on parenchymal and vascular enhancement during multiphasic abdominal multidetector-row computed tomography (MDCT). METHODS: Fifteen patients underwent MDCT at an iodine flow rate of 1.2 g/s as well as 1.6 g/s (group A, protocols 1 and 2), and 90 patients underwent MDCT at an iodine flow rate of 1.2 g/s (group B) or 1.6 g/s (group C). Measurements were performed for all groups in the liver, spleen, pancreas, portal vein, inferior vena cava, and abdominal aorta. RESULTS: Aortal and pancreatic enhancement during the arterial phase was significantly higher with the higher iodine flow rate. The mean difference in aortal enhancement was 60 Hounsfield units (HU) between protocols 1 and 2 of group A, and the mean difference was 70 HU between groups B and C. The mean difference in pancreatic enhancement was 10 HU between protocols 1 and 2 of group A and 17 HU between groups B and C. During the portal and hepatic venous phases, no significant difference in enhancement was observed. CONCLUSION: A high iodine flow rate in multiphasic abdominal MDCT improves enhancement of the aorta and the pancreas during the arterial phase but does not influence later phases.

Surgical therapy options in polycystic liver disease.

INTRODUCTION: Polycystic liver disease (PLD) is a rare affliction frequently observed in association with polycystic kidney disease. Only symptomatic patients require treatment, which can be conservative or surgical, i.e. laparoscopic or conventional. We report the results of our experience in the surgical management of polycystic liver disease. METHODS: Between 1994 and 2003, 19 patients (16 female, 3 male) were referred to our center for the management of PLD. Their median age was 50 years (range 33-72). All were symptomatic and their cysts had a median diameter of 11 cm (range 5-22). RESULTS: Laparoscopic management was undertaken in eight patients, with one conversion to open technique because of bleeding from a superficial hepatic vein. An open procedure was performed in 11 patients: one left hemihepatectomy, deroofing in two patients, segment resection 2/3 plus deroofing in six patients, and segment resection 5/6 plus deroofing in two patients. Four patients had complications: one case of biliary leakage was managed conservatively; two patients had pneumothorax caused by the cava catheter inserted for anesthesia, and one patient's abdominal drain tore off and had to be removed by relaparotomy on the fourth postoperative day. Median follow-up of all patients was 49 months (range 7-98). In one patient there was symptomatic recurrence with hepatomegaly and compression of the inferior vena cava 84 months after the first operation. CONCLUSIONS: Careful selection of patients and meticulous surgical technique are recommended in the management of PLD. The treatment of choice for symptomatic Gigot or Morino type 1 PLD is laparoscopic surgery, and for advanced stage PLD combined hepatic resection and cyst fenestration.

MDCT angiography of the pulmonary arteries: influence of iodine flow concentration on vessel attenuation and visualization.

OBJECTIVE: Our objective was to assess the influence of iodine flow concentration on attenuation and visualization of the pulmonary arteries in thoracic MDCT angiography. MATERIALS AND METHODS: One hundred consecutive patients who were referred to our department with suspected acute pulmonary embolism underwent MDCT angiography of the pulmonary arteries either with 120 mL of standard contrast medium (300 mg I/mL) (group A) or with 90 mL of high-concentration contrast medium (400 mg I/mL) (group B). The contrast medium was injected at a flow rate of 4 mL/sec. The scan delay was determined using a semiautomatic bolus-tracking system in all examinations conducted with the same scanning parameters. Quantitative analysis was performed by region-of-interest measurements along the z-axis to compare the attenuation profiles of the two groups. Attenuation of the fourth-, fifth-, and sixth-order arteries was assessed visually for differences between the two groups. RESULTS: The mean enhancement along the z-axis was 268 +/- 56 H in group A and 344 +/- 108 in group B. The difference of 76 H was statistically significant (p < 0.001). The attenuation profile was similar in both groups. The detection rate of fifth- and sixth-order arteries was significantly higher in group B than in group A (94% compared with 91% and 72% compared with 60%, respectively, p < 0.01). CONCLUSION: Use of a high flow concentration of iodine in MDCT angiography of the pulmonary arteries significantly increases attenuation of the pulmonary arteries, thereby improving visualization of subsegmental pulmonary arteries.

Optimized imaging of pulmonary embolism.

Pulmonary embolism (PE) is a common disease with considerable mortality. There are no specific signs or symptoms of PE; the diagnosis relies on imaging tests. The development of multi-detector computed tomography has led to an improvement in the diagnosis of PE due to faster scanning and improved spatial resolution along the longitudinal axis of the patient. Apart from fast scanning and thin collimation, optimal arterial attenuation remains one of the most crucial determinants of sufficient depiction of the pulmonary arteries. Arterial attenuation over time is generally determined by iodine flow concentration, which may be increased either by raising the contrast medium flow rate, and/or by using a high iodine concentration contrast medium. The scan duration necessary for imaging the whole thorax ranges from about 20 s with a four-detector row scanner to about 5 s with a 64-detector row detector scanner. The collimation ranges from 0.5 mm to 1 mm depending on the scanner used. This enables the most detailed display of the pulmonary arteries. Bolus triggering devices are a valuable tool for accurate timing of scanning. The administration of the contrast material bolus is performed using a power injector at a flow rate of about 4 mL/s. A saline flush immediately after contrast material administration avoids pooling of the contrast material in the arm veins and in the injection system and reduces perivenous artifacts in the superior vena cava. The use of a high concentration contrast material significantly improves attenuation of the pulmonary arteries leading to better visualisation of sub-segmental and lower order pulmonary arteries in multi-row-detector-CTA. In addition, the higher attenuation may improve the conspicuity of emboli within the pulmonary arteries.