Subspecialization in radiology: effects on the diagnostic spectrum of radiologists and report turnaround time in a Swiss university hospital.

PURPOSE: To analyze the changes in the work profiles of radiologists and the reporting time after the implementation of professional subspecialization in the radiology department of a Swiss university hospital. METHODS: In a retrospective analysis, the overall number of different radiologic examinations performed in the department of radiology of the largest Swiss university hospital was documented for 2014 and 2016 before and after the implementation of subspecialized reporting (subspecialities: abdominal, musculoskeletal, cardiothoracic, emergency, and pediatric imaging) in May 2015. For six selected radiologists, the number and types of reported examinations as well as the related radiology report turnaround times (RTATs) were analyzed in detail and compared between the two 1-year periods. RESULTS: Overall, there was a significant increase of 10.3% in the total number of examinations performed in the whole department in 2016 compared with 2014. For four of the six radiologists, the range of different types of examinations significantly decreased with the introduction of subspecialized reporting (p < 0.05). Furthermore, there was a significant change in the subset of the ten most commonly reported types of examinations reported by each of the six radiologists. Mean overall RTATs significantly increased for five of the six radiologists (p < 0.05). CONCLUSIONS: Implementation of subspecialized reporting led to a change in the structure and a decrease in the range of different examination types reported by each radiologist. Mean RTAT increased for most radiologists. Subspecialized reporting allows the individual radiologist to focus on a special field of professional competence but can result in longer overall RTAT.

Image quality of low-radiation dose left atrial CT using filtered back projection and an iterative reconstruction algorithm: intra-individual comparison in unselected patients undergoing pulmonary vein isolation.

Background Computed tomography (CT) of the left atrium (LA) is performed prior to pulmonary vein isolation (PVI) to improve success of circumferential ablation for atrial fibrillation. The ablation procedure itself exposes patients to substantial radiation doses, therefore radiation dose reduction in pre-ablational imaging is of concern. Purpose To assess and compare diagnostic performance of low-radiation dose preprocedural CT in patients scheduled for PVI using two types of reconstruction algorithms. Material and Methods Forty-six patients (61 ± 10 years) scheduled for PVI were enrolled in this study irrespective of body-mass-index or cardiac rhythm at examination. An electrocardiographically triggered dual-source CT scan was performed. Filtered back projection (FBP) and iterative reconstruction (IR) algorithms were applied. Images were integrated into an electroanatomic mapping (EAM) system. Subjective image quality was scored independently by two readers on a five-point scale for both reconstruction algorithms (1 = excellent to 5 = non-diagnostic). Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and effective radiation dose were calculated. Results Data acquisition and EAM integration were successful in all patients. Median image quality score was 1 for both FBP (quartiles = 1, 1.62; range = 1-3) and IR (quartiles = 1, 1.5; range = 1-3). Mean SNR was 7.61 ± 2.14 for FBP and 9.02 ± 2.69 for IR. Mean CNR was 5.92 ± 1.80 for FBP and 6.95 ± 2.29 for IR. Mean effective radiation dose was 0.3 ± 0.1 mSv. Conclusion At a radiation dose of 0.3 ± 0.1 mSv, high-pitch dual-source CT yields LA images of consistently high quality using both FBP and IR. IR raises SNR and CNR without significantly improving subjective image quality.

Consensus report from the 7th International Forum for Liver Magnetic Resonance Imaging.

OBJECTIVES: Liver-specific MRI is a fast-growing field, with technological and protocol advancements providing more robust imaging and allowing a greater depth of information per examination. This article reports the evidence for, and expert thinking on, current challenges in liver-specific MRI, as discussed at the 7th International Forum for Liver MRI, which was held in Shanghai, China, in October 2013. METHODS: Topics discussed included the role of gadoxetic acid-enhanced MRI in the differentiation of focal nodular hyperplasia from hepatocellular adenoma and small hepatocellular carcinoma (HCC) from small intrahepatic cholangiocarcinoma (in patients with chronic liver disease), the differentiation of low-grade dysplastic nodule (DN) from pre-malignant high-grade DN and early HCC, and treatment planning and assessment of treatment response for patients with HCC and colorectal liver metastasis. Optimization of the gadoxetic acid-enhanced MRI protocol to gain robust arterial and hepatobiliary phase images was also discussed. RESULTS AND CONCLUSIONS: Gadoxetic acid-enhanced MRI demonstrates added value for the detection and characterization of focal liver lesions and shows promise in a number of new indications, including regional liver functional assessment and patient monitoring after therapy; however, more data are needed in some areas, and further developments are needed to translate cutting-edge techniques into clinical practice. KEY POINTS: Liver-specific MRI is a fast-growing field, with many technological and protocol advancements. Gadoxetic acid-enhanced MRI demonstrates value for detecting and characterizing focal liver lesions. Gadoxetic acid-enhanced MRI shows promise in regional functional assessment and patient monitoring. Further developments are needed to translate cutting-edge techniques into clinical practice.

Intraindividual, randomized comparison of the macrocyclic contrast agents gadobutrol and gadoterate meglumine in breast magnetic resonance imaging.

OBJECTIVES: To compare intraindividually two macrocyclic contrast agents - gadobutrol and gadoterate meglumine (Gd-DOTA) - for dynamic and quantitative assessment of relative enhancement (RE) in benign and malignant breast lesions. METHODS: This was an ethically approved, prospective, single-centre, randomized, crossover study in 52 women with suspected breast lesions referred for magnetic resonance imaging (MRI). Each patient underwent one examination with gadobutrol and one with Gd-DOTA (0.1 mmol/kg BW) on a 1.5 T system 1 - 7 days apart. Dynamic, T1-weighted, 3D gradient echo sequences were acquired under identical conditions. Quantitative evaluation with at least three regions of interest (ROI) per lesion was performed. Primary endpoint was RE during the initial postcontrast phase after the first and second dynamic acquisition, and peak RE. All lesions were histologically proven; differences between the examinations were evaluated. RESULTS: Forty-five patients with a total of 11 benign and 34 malignant lesions were assessed. Mean RE was significantly higher for gadobutrol than Gd-DOTA (p < 0.0001). Gadobutrol showed significantly less washout (64.4 %) than Gd-DOTA (75.4 %) in malignant lesions (p = 0.048) CONCLUSIONS: Gadobutrol has higher RE values compared with Gd-DOTA, whereas Gd-DOTA shows more marked washout in malignant lesions. This might improve the detection of breast lesions and influence the specificity of breast MRI-imaging.

Low Dose Computed Tomography for 3D Planning of Total Hip Arthroplasty: Evaluation of Radiation Exposure and Image Quality.

OBJECTIVE: The aim of the study was to compare radiation exposure and image quality between dedicated computed tomography (CT) protocols for preoperative total hip arthroplasty (THA) planning. METHODS: Three protocols with automated tube current modulation using 64-slice (n = 177) and 128-slice CT scanners without (n = 129) and with automated tube voltage preselection (n = 84) were compared. RESULTS: All 390 CTs were of sufficient quality for THA planning. Mean DLP was 235.0 mGy*cm (effective dose 2.8 mSv). Lowest radiation exposure (2.5 mSv) was seen with automated voltage preselection and the algorithm's selection was 100 kV (90.5% of patients) and 120 kV. Lowest image noise was seen in the highest dose group (3.1 mSv, 128-slice CT fixed tube voltage). A significant difference in cortical bone radiodensity was seen between 100 kV and 120 kV (P < 0.0001). CONCLUSIONS: Preoperative pelvic CT for THA planning is possible with very low radiation dose and reliable quality. Automated voltage preselection further decreases the effective dose by 18.2%.

Dual-energy computed tomography for the assessment of early treatment effects of regorafenib in a preclinical tumor model: comparison with dynamic contrast-enhanced CT and conventional contrast-enhanced single-energy CT.

OBJECTIVES: The potential diagnostic value of dual-energy computed tomography (DE-CT) compared to dynamic contrast-enhanced CT (DCE-CT) and conventional contrast-enhanced CT (CE-CT) in the assessment of early regorafenib treatment effects was evaluated in a preclinical setting. METHODS: A rat GS9L glioma model was examined with contrast-enhanced dynamic DE-CT measurements (80 kV/140 kV) for 4 min before and on days 1 and 4 after the start of daily regorafenib or placebo treatment. Tumour time-density curves (0-240 s, 80 kV), DE-CT (60 s) derived iodine maps and the DCE-CT (0-30 s, 80 kV) based parameters blood flow (BF), blood volume (BV) and permeability (PMB) were calculated and compared to conventional CE-CT (60 s, 80 kV). RESULTS: The regorafenib group showed a marked decrease in the tumour time-density curve, a significantly lower iodine concentration and a significantly lower PMB on day 1 and 4 compared to baseline, which was not observed for the placebo group. CE-CT showed a significant decrease in tumour density on day 4 but not on day 1. The DE-CT-derived iodine concentrations correlated with PMB and BV but not with BF. CONCLUSIONS: DE-CT allows early treatment monitoring, which correlates with DCE-CT. Superior performance was observed compared to single-energy CE-CT. KEY POINTS: • Regorafenib treatment response was evaluated by CT in a rat tumour model. • Dual-energy contrast-enhanced CT allows early treatment monitoring of targeted anti-tumour therapies. • Dual-energy CT showed higher diagnostic potential than conventional contrast enhanced single-energy CT. • Dual-energy CT showed diagnostic potential comparable to dynamic contrast-enhanced CT. • Dual-energy CT is a promising method for efficient clinical treatment response evaluation.

High-pitch dual-source CT coronary angiography with low volumes of contrast medium.

OBJECTIVES: To assess the effect of lower volumes of contrast medium (CM) on image quality in high-pitch dual-source computed tomography coronary angiography (CTCA). METHODS: One-hundred consecutive patients (body weight 65-85 kg, stable heart rate ≤65 bpm, cardiac index ≥2.5 L/min/m(2)) referred for CTCA were prospectively enrolled. Patients were randomly assigned to one of five groups of different CM volumes (G30, 30 mL; G40, 40 mL; G50, 50 mL; G60, 60 mL; G70, 70 mL; flow rate 5 mL/s each, iodine content 370 mg/mL). Attenuation within the proximal and distal coronary artery segments was analysed. RESULTS: Mean attenuation for men and women ranged from 345.0 and 399.1 HU in G30 to 478.2 and 571.8 HU in G70. Mean attenuation values were higher in groups with higher CM volumes (P < 0.0001) and higher in women than in men (P < 0.0001). The proportions of segments with attenuation of at least 300 HU in G30, G40, G50, G60 and G70 were 89 %, 95 %, 98 %, 98 % and 99 %. CM volume of 30 mL in women and 40 mL in men proved to be sufficient to guarantee attenuation of at least 300 HU. CONCLUSIONS: In selected patients high-pitch dual-source CTCA can be performed with CM volumes of 40 mL in men or 30 mL in women. KEY POINTS: • High-pitch dual-source coronary angiography is feasible with low contrast media volumes. • Traditional injection rules still apply: higher volumes result in higher enhancement. • The patient's gender is a co-factor determining the level of contrast enhancement. • Volumes can be reduced down to 30-40 mL in selected patients.

Systemic staging for urate crystal deposits with dual-energy CT and ultrasound in patients with suspected gout.

Objective of the study is to compare the diagnostic accuracy for detecting monosodium urate crystal deposits between dual-energy CT (DECT) and ultrasound (US). Sixty consecutive patients (49 men, mean age 62 years) with clinically suspected gout were included in this case-control study. DECT and US of feet, knees, hands and elbows were performed in all patients. Polarisation microscopy of synovial fluid or a score incorporating serum uric acid level, first MTP joint involvement, gender, previous patient-reported arthritis attack, cardiovascular diseases, joint redness and onset within 1 day was used as standard of reference. Standard of reference classified 39 patients as gout positive. Sixteen patients had gout and a concomitant rheumatic disease. Sensitivities for diagnosis of gout disease were 84.6 % (33/39) for DECT and 100 % (39/39) for US. Specificities were 85.7 % (18/21) for DECT and 76.2 % (16/21) for US. Positive and negative predictive values were 91.7 % (33/36) and 75.0 % (18/24) for DECT, 88.6 % (39/44) and 100 % (16/16) for US, respectively. Urate crystals were detected most frequently in MTP1 joints (DECT 20/78, US 58/78), any other toe joints (DECT 25/78, US 62/78) and knees (DECT 41/78, US 31/78). The volumetry of DECT computed a mean urate crystal deposit load of 2.1 cm(3) (SD 9.6 cm(3)). A mean effective dose of ≤0.5 mSv was estimated. DECT is more specific for the diagnosis of gout than US. However, it fails to detect small urate crystal deposits. It might be particularly useful for patients with ambivalent findings, concomitant rheumatic diseases and with non-conclusive joint aspiration.

Continuously moving table aorto-iliofemoral run-off contrast-enhanced magnetic resonance angiography: image quality analysis in comparison to the multistep acquisition.

BACKGROUND: Optimal vessel contrast is a prerequisite for vascular imaging. Consecutive stationary imaging of multiple fields of view is contrary to the continuous contrast material passage through the vascular tree. A continuous acquisition of a magnetic resonance (MR) sequence might overcome this limitation. PURPOSE: To investigate the image quality of a continuously moving table (CMT) acquisition compared with the established multistep approach for contrast-enhanced magnetic resonance angiography (CE-MRA) of the aorto-iliofemoral run-off. MATERIAL AND METHODS: Institutional review board approved this retrospective interindividual study of 60 consecutive patients referred to CE-MRA for peripheral arterial disease. Thirty patients underwent CE-MRA using the routine multistep acquisition and 30 patients were scanned using the CMT technique at 1.5 Tesla. All patients received a fixed contrast dose of 25 mL gadoterate meglumine. A quantitative analysis was performed to assess the relative contrast of 10 vascular segments from the proximal abdominal aorta to the distal calf arteries. A qualitative evaluation of three separate vascular regions (abdomen and pelvis, thighs, and calves) was performed. Two radiologists graded independently arterial vessel conspicuity, venous contamination, presence of artifacts, and diagnostic confidence on a 4-point scale. Overall scan time, including all localizer scans, was recorded. Statistical differences were tested using the Wilcoxon signed-rank test with Bonferroni correction. RESULTS: No significant differences were found between the continuously moving table acquisition and the multistep acquisition with regard to the relative vascular contrast and the qualitative image criteria. The agreement between both readers was significant (Kendall tau rank correlation coefficient, 0.373). The absolute reader agreement was 71.4%. The mean overall scan time was 12 min 44 s for the CMT protocol and 21 min 41 s for the multistep protocol. CONCLUSION: Aorto-iliofemoral run-off CE-MRA acquired with CMT technique provides a high image quality equivalent to a multistep technique at an overall scan time reduction of 41.3%.

Computed tomography for preoperative planning in total hip arthroplasty: what radiologists need to know.

The number of total hip arthroplasties is continuously rising. Although less invasive surgical techniques, sophisticated component design, and intraoperative navigation techniques have been introduced, the rate of peri- and postoperative complications, including dislocations, fractures, nerve palsies, and infections, is still a major clinical problem. Better patient outcome, faster recovery and rehabilitation, and shorter operation times therefore remain to be accomplished. A promising strategy is to use minimally invasive techniques in conjunction with modular implants, aimed at independently reconstructing femoral offset and leg length on the basis of highly accurate preoperative planning. Plain radiographs have clear limitations for the correct estimation of hip joint geometry and bone quality. Three-dimensional assessment based on computed tomography (CT) allows optimizing the choice and positions of implants and anticipating difficulties to be encountered during surgery. Postoperative CT is used to monitor operative translation and plays a role in arthroplastic quality management. Radiologists should be familiar with the needs of orthopedic surgeons in terms of CT acquisition, post-processing, and data transfer. The CT protocol should be optimized to enhance image quality and reduce radiation exposure. When dedicated orthopedic CT protocols and state-of-the-art scanner hardware are used, radiation exposure can be decreased to a level just marginally higher than that of conventional preoperative radiography. Surgeons and radiologists should use similar terminology to avoid misunderstanding and inaccuracies in the transfer of preoperative planning.

Evaluation of guided reporting: quality and reading time of automatically generated radiology report in breast magnetic resonance imaging using a dedicated software solution.

PURPOSE: Unstructured, free-text dictation (FT), the current standard in breast magnetic resonance imaging (MRI) reporting, is considered time-consuming and prone to error. The purpose of this study is to assess the usability and performance of a novel, software-based guided reporting (GR) strategy in breast MRI. METHODS: Eighty examinations previously evaluated for a clinical indication (e.g., mass and focus/non-mass enhancement) with FT were reevaluated by three specialized radiologists using GR. Each radiologist had a different number of cases (R1, n = 24; R2, n = 20; R3, n = 36). Usability was assessed by subjective feedback, and quality was assessed by comparing the completeness of automatically generated GR reports with that of their FT counterparts. Errors in GR were categorized and analyzed for debugging with a final software version. Combined reading and reporting times and learning curves were analyzed. RESULTS: Usability was rated high by all readers. No non-sense, omission/commission, or translational errors were detected with the GR method. Spelling and grammar errors were observed in 3/80 patient reports (3.8%) with GR (exclusively in the discussion section) and in 36/80 patient reports (45%) with FT. Between FT and GR, 41 patient reports revealed no content differences, 33 revealed minor differences, and 6 revealed major differences that resulted in changes in treatment. The errors in all patient reports with major content differences were categorized as content omission errors caused by improper software operation (n = 2) or by missing content in software v. 0.8 displayable with v. 1.7 (n = 4). The mean combined reading and reporting time was 576 s (standard deviation: 327 s; min: 155 s; max: 1,517 s). The mean times for each reader were 485, 557, and 754 s, and the respective learning curves evaluated by regression models revealed statistically significant slopes (P = 0.002; P = 0.0002; P < 0.0001). Overall times were shorter compared with external references that used FT. The mean combined reading and reporting time of MRI examinations using FT was 1,043 s and decreased by 44.8% with GR. CONCLUSION: GR allows for complete reporting with minimized error rates and reduced combined reading and reporting times. The streamlining of the process (evidenced by lower reading times) for the readers in this study proves that GR can be learned quickly. Reducing reporting errors leads to fewer therapeutic faults and lawsuits against radiologists. It is known that delays in radiology reporting hinder early treatment and lead to poorer patient outcomes. CLINICAL SIGNIFICANCE: While the number of scans and images per examination is continuously rising, staff shortages create a bottleneck in radiology departments. The IT-based GR method can be a major boon, improving radiologist efficiency, report quality, and the quality of simultaneously generated data.

Macrocyclic contrast agents for magnetic resonance imaging of chronic myocardial infarction: intraindividual comparison of gadobutrol and gadoterate meglumine.

OBJECTIVES: To compare 0.15 mmol/kg gadobutrol for late gadolinium enhancement (LGE) imaging of chronic myocardial infarction with a relaxivity-adjusted dose of gadoterate meglumine (Gd-DOTA). METHODS: Seventeen patients with suspected chronic myocardial infarction underwent LGE imaging at 1.5 T, acquiring an inversion-recovery-prepared gradient echo sequence 15 min after contrast agent administration. Each patient underwent LGE imaging twice, once after administration of 0.15 mmol/kg gadobutrol (r1 = 5.2 l mmol(-1) s(-1)) and after 0.22 mmol/kg Gd-DOTA (r1 = 3.6 l mmol(-1) s(-1)). Two readers independently determined infarct size and contrast-to-noise ratios of infarcted myocardium to remote myocardium (CNR(remote)) and to the left ventricular lumen (CNR(lumen)). RESULTS: LGE was present in 14 patients. Infarct sizes determined after administration of gadobutrol [23.4 ml; 95 % CI (14.4; 32.5)] and Gd-DOTA [22.1 ml; 95 % CI (13.0; 31.1)] were not statistically different (P = 0.22). The CNR(remote) of LGE in infarcted myocardium on gadobutrol- and Gd-DOTA-enhanced images was 44.1 [95 % CI (31.0; 57.1)] and 45.2 [95 % CI (32.2; 58.3)], respectively (P = 0.73). CNR(lumen) was significantly higher on gadobutrol-enhanced LGE images [12.7; 95 % CI (2.5; 23.0) versus 6.8; 95 % CI (-3.5; 17.0); P = 0.02]. CONCLUSION: At relaxivity-adjusted doses, gadobutrol and Gd-DOTA yielded similar infarct sizes with superior contrast between infarcted myocardium and left ventricular lumen on gadobutrol-enhanced images.

Cost-effectiveness of cardiovascular magnetic resonance and single-photon emission computed tomography for diagnosis of coronary artery disease in Germany.

BACKGROUND: Recent studies have demonstrated a superior diagnostic accuracy of cardiovascular magnetic resonance (CMR) for the detection of coronary artery disease (CAD). We aimed to determine the comparative cost-effectiveness of CMR versus single-photon emission computed tomography (SPECT). METHODS: Based on Bayes' theorem, a mathematical model was developed to compare the cost-effectiveness and utility of CMR with SPECT in patients with suspected CAD. Invasive coronary angiography served as the standard of reference. Effectiveness was defined as the accurate detection of CAD, and utility as the number of quality-adjusted life-years (QALYs) gained. Model input parameters were derived from the literature, and the cost analysis was conducted from a German health care payer's perspective. Extensive sensitivity analyses were performed. RESULTS: Reimbursement fees represented only a minor fraction of the total costs incurred by a diagnostic strategy. Increases in the prevalence of CAD were generally associated with improved cost-effectiveness and decreased costs per utility unit (ΔQALY). By comparison, CMR was consistently more cost-effective than SPECT, and showed lower costs per QALY gained. Given a CAD prevalence of 0.50, CMR was associated with total costs of €6,120 for one patient correctly diagnosed as having CAD and with €2,246 per ΔQALY gained versus €7,065 and €2,931 for SPECT, respectively. Above a threshold value of CAD prevalence of 0.60, proceeding directly to invasive angiography was the most cost-effective approach. CONCLUSIONS: In patients with low to intermediate CAD probabilities, CMR is more cost-effective than SPECT. Moreover, lower costs per utility unit indicate a superior clinical utility of CMR.

Consensus report of the Fifth International Forum for Liver MRI.

OBJECTIVE: This article reviews topics discussed during the Fifth International Forum for Liver MRI (with a focus on gadoxetic acid-enhanced MRI), which was held in Munich, Germany, in September 2011. CONCLUSION: Growing evidence shows that gadoxetic acid-enhanced MRI has high sensitivity and specificity for diagnosing liver tumors. Hepatobiliary phase imaging adds new information for the characterization of borderline lesions. However, there is a need to develop standardized criteria for interpretation of gadoxetic acid-enhanced MRI in patients with cirrhosis or other risk factors for hepatocellular carcinoma.

Cost comparison of 111In-DTPA-octreotide scintigraphy and 68Ga-DOTATOC PET/CT for staging enteropancreatic neuroendocrine tumours.

PURPOSE: Although somatostatin receptor positron emission tomography (PET)/CT is gaining increasing popularity and has shown its diagnostic superiority in several studies, (111)In-diethylenetriaminepentaacetic acid (DTPA)-octreotide is still the current standard for diagnosis of neuroendocrine tumours (NET). The aim of this study was to compare the costs for the two diagnostic tests and the respective consequential costs. METHODS: From January 2009 to July 2009, 51 consecutive patients with enteropancreatic NET who underwent contrast-enhanced (68)Ga-DOTATOC PET/CT (n = 29) or (111)In-DTPA-octreotide (mean 3 whole-body scans plus 1.6 low-dose single photon emission computed tomography/CT; n = 22) were included. For cost analysis, direct costs (equipment) and variable costs (material, labour) per examination were calculated. Additionally required CT and/or MRI examinations within the staging process were assessed as consequential costs. An additional deterministic sensitivity analysis was performed. RESULTS: A (68)Ga-DOTATOC PET/CT examination yielded total costs (equipment, personnel and material costs) of 548 euro. On the other hand, an (111)In-DTPA-octreotide examination resulted in 827 euro total costs. Costs for equipment and material had a share of 460 euro/720 euro for (68)Ga-DOTATOC/(111)In-DTPA-octreotide and labour costs of 89 euro/106 euro. With (68)Ga-DOTATOC additional MRI had to be performed in 7% of the patients resulting in a mean of 20 euro for supplementary imaging per patient; 82% of patients with (111)In-DTPA-octreotide needed additional MRI and/or CT resulting in mean additional costs of 161 euro per patient. CONCLUSION: (68)Ga-DOTATOC PET/CT was considerably cheaper than (111)In-DTPA-octreotide with respect to both material and personnel costs. Furthermore, by using (68)Ga-DOTATOC PET/CT considerably fewer additional examinations were needed reducing the consequential costs significantly.

Single beat 3D echocardiography for the assessment of right ventricular dimension and function after endurance exercise: Intraindividual comparison with magnetic resonance imaging.

BACKGROUND: Our study compares new single beat 3D echocardiography (sb3DE) to cardiovascular magnetic resonance imaging (CMR) for the measurement of right ventricular (RV) dimension and function immediately after a 30 km run. This is to validate sb3DE against the "gold standard" CMR and to bring new insights into acute changes of RV dimension and function after endurance exercise. METHODS: 21 non-elite male marathon runners were examined by sb3DE (Siemens ACUSON SC2000, matrix transducer 4Z1c, volume rates 10-29/s), CMR (Siemens Magnetom Avanto, 1,5 Tesla) and blood tests before and immediately after each athlete ran 30 km. The runners were not allowed to rehydrate after the race. The order of sb3DE and CMR examination was randomized. RESULTS: Sb3DE for the acquisition of RV dimension and function was feasible in all subjects. The decrease in mean body weight and the significant increase in hematocrit indicated dehydration. RV dimensions measured by CMR were consistently larger than measured by sb3DE.Neither sb3DE nor CMR showed a significant difference in the RV ejection fraction before and after exercise. CMR demonstrated a significant decrease in RV dimensions. Measured by sb3DE, this decrease of RV volumes was not significant. CONCLUSION: First, both methods agree well in the acquisition of systolic RV function. The dimensions of the RV measured by CMR are larger than measured by sb3DE. After exercise, the RV volumes decrease significantly when measured by CMR compared to baseline.Second, endurance exercise seems not to induce acute RV dysfunction in athletes without rehydration.

Contrast agents as a biological marker in magnetic resonance imaging of the liver: conventional and new approaches.

Liver imaging is an important clinical area in everyday practice. The clinical meaning of different lesion types in the liver can be quite different. Therefore, the result of imaging studies of the liver can change therapeutic concepts fundamentally. Contrast agents are used in the majority of MR examinations of the liver parenchyma-despite the already good soft-tissue contrast in plain MRI. This can be explained by the advantages in lesion detection and characterization of contrast-enhanced MRI of the liver. Beyond the qualitative evaluation of contrast-enhanced liver MR examinations, quantification of parameters will be the demand of the future. This can be achieved by perfusion MRI, also called dynamic contrast-enhanced MRI (DCE-MRI) of the liver. Its basic principles and different clinical applications will be discussed in this article. Definite cut-off values to determine disease or therapeutic response will help to increase the objectivity and reliability of liver MRI in future. This is especially important in the oncological setting, where modern therapies cannot be assessed based on changes in size only.

Areas suspicious for prostate cancer: MR-guided biopsy in patients with at least one transrectal US-guided biopsy with a negative finding--multiparametric MR imaging for detection and biopsy planning.

PURPOSE: To prospectively investigate the incremental value of multiparametric magnetic resonance (MR) imaging compared with standard T2-weighted imaging for biopsy planning. MATERIALS AND METHODS: The study was approved by the institutional review board; informed consent was obtained. Consecutive patients underwent T2-weighted imaging supplemented with multiparametric 1.5-T MR imaging, consisting of hydrogen 1 ((1)H) MR spectroscopy, diffusion-weighted (DW) imaging, and contrast material-enhanced MR imaging. Quantitative parameters were calculated: (choline plus creatine)-to-citrate ratio, apparent diffusion coefficient, and volume transfer constant and exchange rate constant. The prostate was divided into 20 standardized areas. Each area was classified as benign, inconclusive, or suspicious at T2-weighted imaging, followed by quantitative evaluation of all inconclusive and suspicious areas with multiparametric MR imaging. MR-guided biopsy was performed in lesions classified as suspicious for cancer with at least one of the techniques after transfer to three-dimensional T2-weighted images. Diagnostic parameters were calculated on a per-lesion and per-patient basis for all combinations of T2-weighted imaging with multiparametric MR imaging. RESULTS: Fifty-four patients had a median of two prior transrectal ultrasonographic biopsies with negative findings. Each patient had a median of three suspicious lesions. Prostate cancer was demonstrated in 21 of 54 patients. Biopsy was performed in 178 lesions; 53 were positive for prostate cancer. Detection rates and test negative results, respectively, were as follows: T2-weighted imaging, 70% and 50%; T2-weighted imaging and (1)H MR spectroscopy, 81% and 32%; T2-weighted imaging and contrast-enhanced MR imaging, 83% and 29%; T2-weighted imaging and DW imaging, 85% and 30%; T2-weighted imaging, (1)H MR spectroscopy, and contrast-enhanced MR imaging, 91% and 13%; T2-weighted imaging, (1)H MR spectroscopy, and DW imaging, 94% and 15%; T2-weighted imaging, DW imaging, and contrast-enhanced MR imaging, 94% and 13%; T2-weighted imaging, (1)H MR spectroscopy, DW imaging, and contrast-enhanced MR imaging, 100% and 0%. CONCLUSION: Only the combination of T2-weighted imaging with all three multiparametric techniques depicts all identifiable prostate cancers; a double combination with DW imaging and (1)H MR spectroscopy or contrast-enhanced MR imaging misses 6%, while reasonably reducing the number of areas needing biopsy.

Evaluation of possible drug-drug interaction between gadoxetic acid and erythromycin as an inhibitor of organic anion transporting peptides (OATP).

PURPOSE: To evaluate if erythromycin compromises liver-specific enhancement of gadoxetic acid; both compounds competing in organic anion transporting peptides (OATP) -mediated hepatocytic uptake. MATERIALS AND METHODS: The study was approved by institutional review board. Twelve healthy subjects (nine men, three woman; mean age, 38.7 years) were examined twice by MR imaging with prior administration of NaCl solution (placebo) or 1000 mg of erythromycin following a randomized sequence. Gadoxetic acid (0.025 mmol/kg body weight) was administered 15 min after the end of infusions. Pre- and 20 min postcontrast two-dimensional gradient-recalled-echo sequences were acquired. Relative enhancements of liver parenchyma and ratio of means were calculated from signal intensity measurements. Plasma levels of gadoxetic acid and erythromycin were determined and given in geometric means and coefficients of variation (CV). RESULTS: Concentration of erythromycin directly after end of infusion was 13.9 mg/L (CV 14.9%). Gadolinium plasma concentrations 5 min after gadoxetic acid administration were 138.7 µmol/L (CV 20.4%) after erythromycin infusion and 129.6 µmol/L (CV 22.8%) after placebo. Mean relative enhancements of liver parenchyma were 88.1 (SD 24.9%) after erythromycin infusion and 92.6 (SD 17.9%) after placebo. Ratio of relative enhancements was 0.951 (95% confidence interval, 0.833; 1.061; statistically not significant). CONCLUSION: Coadministration of erythromycin has no effect on gadoxetic acid enhanced liver MR imaging.