Ultra-low-dose dual-source CT coronary angiography with high pitch: diagnostic yield of a volumetric planning scan and effects on dose reduction and imaging strategy.

OBJECTIVE: To evaluate the role of an ultra-low-dose dual-source CT coronary angiography (CTCA) scan with high pitch for delimiting the range of the subsequent standard CTCA scan. METHODS: 30 patients with an indication for CTCA were prospectively examined using a two-scan dual-source CTCA protocol (2.0 × 64.0 × 0.6 mm; pitch, 3.4; rotation time of 280 ms; 100 kV): Scan 1 was acquired with one-fifth of the tube current suggested by the automatic exposure control software [CareDose 4D™ (Siemens Healthcare, Erlangen, Germany) using 100 kV and 370 mAs as a reference] with the scan length from the tracheal bifurcation to the diaphragmatic border. Scan 2 was acquired with standard tube current extending with reduced scan length based on Scan 1. Nine central coronary artery segments were analysed qualitatively on both scans. RESULTS: Scan 2 (105.1 ± 10.1 mm) was significantly shorter than Scan 1 (127.0 ± 8.7 mm). Image quality scores were significantly better for Scan 2. However, in 5 of 6 (83%) patients with stenotic coronary artery disease, a stenosis was already detected in Scan 1 and in 13 of 24 (54%) patients with non-stenotic coronary arteries, a stenosis was already excluded by Scan 1. Using Scan 2 as reference, the positive- and negative-predictive value of Scan 1 was 83% (5 of 6 patients) and 100% (13 of 13 patients), respectively. CONCLUSION: An ultra-low-dose CTCA planning scan enables a reliable scan length reduction of the following standard CTCA scan and allows for correct diagnosis in a substantial proportion of patients. ADVANCES IN KNOWLEDGE: Further dose reductions are possible owing to a change in the individual patient's imaging strategy as a prior ultra-low-dose CTCA scan may already rule out the presence of a stenosis or may lead to a direct transferal to an invasive catheter procedure.

ECG-gated imaging of the left atrium and pulmonary veins: Intra-individual comparison of CTA and MRA.

AIM: To compare electrocardiography (ECG)-gated computed tomography angiography (CTA) with ECG-gated magnetic resonance angiography (MRA) for assessment of the left atrium (LA) and pulmonary veins (PVs). MATERIAL AND METHODS: Twenty-nine consecutive patients who underwent both cardiac CTA and MRA were evaluated. Contrast-enhanced CTA was performed with prospective ECG-gating using a 320 detector row CT system. Contrast-enhanced MRA was performed with prospective ECG-gating using a 1.5 T MRI system equipped with a 32 channel cardiac coil. MRA was acquired during free-breathing with a navigator-gated inversion-recovery prepared steady-state free precession sequence. Two readers independently assessed the CTA and MRA images for vascular definition of the PVs (from 0, not visualized, to 4, excellent definition) and ostial PV diameters. Variants of LA anatomy were assessed in consensus. RESULTS: CTA was successfully performed in all patients with a mean radiation exposure of 5.1 ± 2.2 mSv. MRA was successfully performed in 27 of 29 patients (93 %). Visual definition of PVs was rated significantly higher on CTA compared to MRA (p < 0.0001; reader 1: excellent/good ratings of CTA versus MRA: 100% versus 86%; reader 2: excellent/good ratings of CTA versus MRA: 99% versus 89%). Assessment of ostial PV diameters showed good correlation between CTA and MRA (reader 1: Pearson r = 0.91; reader 2: Pearson r = 0.82). Moreover, agreement between both imaging methods for evaluation of variants of LA anatomy was high (agreement rate of 95% (95% CI: 92-99%). CONCLUSION: ECG-gated CTA provides higher image quality compared to ECG-gated MRA. Nevertheless, both CTA and MRA provided similar information of LA anatomy and ostial PV diameters.

Uterine artery embolization for symptomatic fibroids: long-term changes in disease-specific symptoms and quality of life.

BACKGROUND: To investigate the long-term changes in health-related quality of life (HRQOL) after uterine artery embolization (UAE) for symptomatic fibroids, we conducted a prospective cohort study. METHODS: Eighty-two women completed the validated uterine fibroid symptom and QOL (UFS-QOL) questionnaire before UAE. Short-term results after a median of 8 months (range: 3-20) have been published previously. Patients were asked to complete the questionnaire again after a median of 6.3 years (range: 5-7.6). Secondary outcome measures were the frequency of additional surgical or endovascular procedures due to treatment failure and the menstrual status. RESULTS: A total of 4/82 patients (5%) were lost to follow-up. Of the remaining 78 patients, 11 underwent surgery or repeat UAE (hysterectomy n = 6, myomectomy n = 1, UAE n = 4) at a median of 13 months (range: 5-70) after UAE. Two patients failed clinically but did not undergo a second intervention. The overall treatment failure rate 6 years after UAE was 17%. Clinical long-term follow-up regarding symptom control and quality of life was available in the remaining 65 patients. Symptom severity scores decreased from a median of 37.50 (quartile range, QR: 28.13-53.13) to 0.00 (QR: 0.00-10.94) (P < 0.001), whereas the HRQOL total score increased from a median of 64.66 (QR: 46.34-79.10) to 100.00 (QR: 96.12-100.00) (P < 0.001). Both scores also improved significantly compared with short-term results (P = 0.006 and P = 0.041). Permanent amenorrhea was observed in five patients at a median of 18 months (range: 10-46) after UAE and at a mean patient age of 50 years. CONCLUSIONS: UAE leads to durable relief of fibroid-related symptoms and sustained improvement in HRQOL. After 6 years, clinical failure can be expected in 17%, and most of these patients require secondary invasive treatment.

Computer-aided pulmonary nodule detection - performance of two CAD systems at different CT dose levels.

PURPOSE: To evaluate the impact of dose reduction on the performance of computer-aided lung nodule detection systems (CAD) of two manufacturers by comparing respective CAD results on ultra-low-dose computed tomography (ULD-CT) and standard dose CT (SD-CT). MATERIALS AND METHODS: Multi-slice computed tomography (MSCT) data sets of 26 patients (13 male and 13 female, patients 31 - 74 years old) were retrospectively selected for CAD analysis. Indication for CT examination was staging of a known primary malignancy or suspected pulmonary malignancy. CT images were consecutively acquired at 5 mAs (ULD-CT) and 75 mAs (SD-CT) with 120 kV tube voltage (1 mm slice thickness). The standard of reference was determined by three experienced readers in consensus. CAD reading algorithms (pre-commercial CAD system, Philips, Netherlands: CAD-1; LungCARE, Siemens, Germany: CAD-2) were applied to the CT data sets. RESULTS: Consensus reading identified 253 nodules on SD-CT and ULD-CT. Nodules ranged in diameter between 2 and 41 mm (mean diameter 4.8 mm). Detection rates were recorded with 72 % and 62 % (CAD-1 vs. CAD-2) for SD-CT and with 73 % and 56 % for ULD-CT. Median false positive rates per patient were calculated with 6 and 5 (CAD-1 vs. CAD-2) for SD-CT and with 8 and 3 for ULD-CT. After separate statistical analysis of nodules with diameters of 5 mm and greater, the detection rates increased to 83 % and 61 % for SD-CT and to 89 % and 67 % for ULD-CT (CAD-1 vs. CAD-2). For both CAD systems there were no significant differences between the detection rates for standard and ultra-low-dose data sets (p > 0.05). CONCLUSION: Dose reduction of the underlying CT scan did not significantly influence nodule detection performance of the tested CAD systems.

Linear and volume measurements of pulmonary nodules at different CT dose levels - intrascan and interscan analysis.

PURPOSE: To compare the interobserver variability of the unidimensional diameter and volume measurements of pulmonary nodules in an intrascan and interscan analysis using semi-automated segmentation software on ultra-low-dose computed tomography (ULD-CT) and standard dose CT (SD-CT) data. MATERIALS AND METHODS: In 33 patients with pulmonary nodules, two chest multi-slice CT (MSCT) datasets (1 mm slice thickness; 20 % reconstruction overlap) had been consecutively acquired with an ultra-low dose (120 kV, 5 mAs) and standard dose technique (120 kV, 75 mAs). MSCT data was retrospectively analyzed using the segmentation software OncoTREAT (MeVis, Bremen, Germany, version 1.3). The volume of 229 solid pulmonary nodules included in the analysis as well as the largest diameter according to RECIST (Response Evaluation Criteria for Solid Tumors) were measured by two radiologists. Interobserver variability was calculated and SD-CT and ULD-CT data compared in an intrascan and interscan analysis. RESULTS: The median nodule diameter (n = 229 nodules) was registered with 8.2 mm (range: 2.8 to 43.6 mm, mean: 10.8 mm). The nodule volume ranged between 0.01 and 49.1 ml (median 0.1 ml, mean 1.5 ml). With respect to interobserver variability, the intrascan analysis did not reveal statistically significant differences (p > 0.05) between ULD-CT and SD-CT with broader limits of agreement for relative differences of RECIST measurements (-31.0 % + 27.0 % mean -2.0 % for SD-CT; -27.0 % + 38.6 %, mean 5.8 % for ULD-CT) than for volume measurements (-9.4 %, 8.0 %, mean 0.7 % for SD-CT; -13 %, 13 %, mean 0.0 % for ULD-CT). The interscan analysis showed broadened 95 % confidence intervals for volume measurements (-26.5 % 29.1 % mean 1.3 %, and -25.2 %, 29.6 %, mean 2.2 %) but yielded comparable limits of agreement for RECIST measurements. CONCLUSION: The variability of nodule volumetry assessed by semi-automated segmentation software as well as nodule size determination by RECIST appears to be independent of the acquisition dose in the CT source dataset. This is particularly important regarding size determination of pulmonary nodules in screening trials using low-dose CT data for follow-up imaging.

[Peripartum changes of the pelvic ring: usefulness of magnetic resonance imaging]. / Peripartale Veränderungen des Beckenringes: Wie sinnvoll ist die Magnetresonanztomografie?

PURPOSE: Postpartum pelvic pain beyond the normal level poses a problem to obstetricians. Beyond normal physiologic loosening of the pubic symphysis and sacroiliac joints (SIJs) during pregnancy, symphyseal separation and rupture must be excluded. The aim of this prospective study was to determine whether magnetic resonance imaging (MRI) allows for reliable differentiation of normal postpartum findings and pathologic lesions. MATERIAL AND METHODS: The study included a total of 77 women (mean age 30), among them 21 healthy subjects (group A), 21 asymptomatic postpartum women (group B), and 35 patients with postpartum pelvic pain (group C). The analyzed parameters comprised symphyseal and iliosacral tenderness, subjective pain assessed on a visual analog scale, and data pertaining to obstetric history. All 77 women underwent 1.5T MRI of the pelvic ring using oblique angulated coronal T 1-weighted and STIR sequences for imaging of the symphysis and SIJs in one slice package. Analysis of the MR images comprised signal intensities of pelvic bone marrow, width of the symphyseal cleft, and the symphyseal capsule. RESULTS: Subjects in group A in general had a normal bone marrow signal. The STIR sequence showed increased signal intensity of the pubic bone near the symphysis in 16 women (76 %) of group B and 31 patients of group C (86 %) (not significant). An increased periarticular bone marrow signal of the SIJs on the STIR images was seen in 13 women (62 %) of group B and 23 patients (63 %) of group C. The mean width of the symphyseal cleft differed significantly among the three groups (3.4 mm vs. 5.4 mm vs. 6.7 mm). A width >10 mm was observed in only 4 cases (11 %). Moreover, associated findings such as interpubic hematoma (n=23) or tears of the symphyseal capsule (n=7) were detected in patients of group C. CONCLUSION: The wide overlap of findings between symptomatic and asymptomatic postpartum patients does not allow reliable differentiation by MRI of normal and abnormal findings. MRI contributes to the differentiation of symphyseal contusion and rupture and provides information on severe associated changes.

Uterine artery embolization for symptomatic fibroids: short-term versus mid-term changes in disease-specific symptoms, quality of life and magnetic resonance imaging results.

BACKGROUND: Prospective study to evaluate changes in symptom severity, health-related quality of life (HRQOL) and uterine and leiomyoma volume after uterine artery embolization (UAE). METHODS: Eighty-two women completed a validated uterine fibroid symptom and quality of life (UFS-QOL) questionnaire and underwent magnetic resonance imaging (MRI) before and 3-20 months after UAE. Primary outcome measures were changes in symptom severity and QOL at short-term follow-up [median 5 (range 3-7) months] and mid-term follow-up [median 14 (8-20) months]. Secondary outcome measures included the frequency of additional procedures to control persistent symptoms and changes in dominant fibroid volume (DFV) and uterine volume (UV). RESULTS: Of 82 patients, 71 (86.6%) patients completed follow-up, 7 (8.5%) patients had a second procedure and 4 (4.9%) were lost to follow-up. Symptom severity scores decreased from a median of 43.75 to 21.88 (P < 0.001) in the short-term follow-up group and from a median of 43.75 to 9.38 (P < 0.001) in the mid-term follow-up group. QOL scores increased from a median of 56.90 to 87.93 (P < 0.001) and 66.81 to 96.12 (P < 0.001), respectively. During short-term follow-up, median UV decreased by 27% (95% CI 20.25-33.81, P < 0.001) and median DFV by 62% (95% CI 47.81-71.55, P < 0.001), whereas UV decreased by 36% (95% CI 23.34-55.02, P < 0.001) and DFV by 66% (95% CI 54.28-71.92, P < 0.001) for the mid-term follow-up group. A decrease in UV correlated with change in symptom severity (P < 0.005). CONCLUSIONS: Women report significant improvements in fibroid-specific symptoms and QOL at short- and mid-term follow-ups after UAE.

Low-field MRI for assessing synovitis in patients with rheumatoid arthritis. Impact of Gd-DTPA dose on synovitis scoring.

OBJECTIVE: To investigate the impact of a double dose compared to a single dose of contrast material in low-field magnetic resonance imaging (MRI) on semi-quantitative scoring of synovitis in patients with rheumatoid arthritis (RA). METHODS: This prospective study included 38 RA patients (23 women and 15 men, mean age 51 years). All patients underwent low-field MRI of the hand before administration of contrast medium, after intravenous injection of 0.1 mmol/kg gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA), and after another dose of 0.1 mmol/kg Gd-DTPA. Two readers (A and B) blinded to dosage independently scored the single dose and double dose image sets for synovitis according to outcome measures in rheumatology (OMERACT) recommendations. Contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were also calculated for each set. RESULTS: 149 metacarpophalangeal (MCP) joints were evaluated. There was good inter-reader agreement for each of the two sets (intra-class correlation coefficient of 0.75 for the single dose set and 0.83 for the double dose). Median CNR and SNR values were 5.4 and 15.9, respectively, for the single dose set and 8.5 and 16.6, respectively, for the double dose set (p<0.0001). Single dose set mean synovitis scores were 1.7 and 1.6 for readers A and B, respectively. Double dose set scores were 1.9 and 2.0, respectively. Thus, higher synovitis scores were recorded for the double dose sets than the single dose sets (p<0.005). CONCLUSION: In low-field MRI, when evaluating RA, the dose of the contrast material influences synovitis scoring. Therefore, dosage of contrast material should be taken into consideration when using extremity dedicated low-field MRI.

[Whole-body MR angiography: comparison of two protocols for contrast media injection]. / Ganzkörper-MR-Angiographie: Vergleich von zwei Protokollen zur Kontrastmittelinjektion.

PURPOSE: To compare two injection strategies for contrast media injection in whole-body MR angiography quantitatively and qualitatively with regard to contrast and image quality. MATERIAL AND METHODS: 40 patients were examined at 1.5 Tesla using either a single injection protocol or a double injection protocol with two separate bolus injections. Vessel regions I (supraaortic/thoracic), II (abdominal/pelvic), III (upper legs) and IV (lower legs) were examined in the following order: single injection: I, II, III, IV, double injection: I and IV after the first injection, II and III after the second bolus injection. Quantitative evaluation: SI measurements were carried out in 2 arteries per region. Contrast values were calculated. Qualitative evaluation: Evaluation of regions I-IV regarding vessel contrast, venous overlay and image quality on a five-point scale by two reviewers in consensus. The Mann-Whitney-U test was used to test the differences for significance. RESULTS: Quantitative evaluation: Using the double injection protocol, significantly higher contrast values in regions I and II and significantly lower contrast values in the subregions IIIa (upper part of III) and IVb (lower part of IV) were obtained (p < 0.05). The mean contrast values in subregions IIIb (lower part of III) and IVa (upper part of IV) were lower using the double injection protocol, but not significantly. Qualitative evaluation: Using the double injection protocol, region II was rated significantly higher (mean ratings: 3.55, 3.45 and 3.5 versus 2.7, 2.5 and 2.55; p < 0.05) and region III significantly lower (mean ratings: 3.1, 2, 2.5 versus 3.9, 3.1 and 3.55; p < 0.05) for all three examined criteria. When using the double injection protocol, ratings were significantly lower in region IV regarding vessel contrast and image quality (mean ratings: 2.4 and 2.15 versus 3.45 and 3.15; p < 0.05). The ratings regarding venous overlay in region IV showed no significant differences (mean ratings: 2.15 versus 2.75; p > 0.05). CONCLUSION: Due to the better results in the supraaortic/thoracic and abdominal/pelvic regions, the double injection protocol is preferred. However, both protocols require further improvement.

[A new method for standardized diagnosis following renal transplantation. Ultrasound with contrast enhancement]. / Eine neue Methode zur standardisierten Diagnostik nach Nierentransplantation. Die ultraschallkontrastmittelgestützte Sonografie.

Ultrasound (US) imaging is an important diagnostic tool following renal transplantation. Unfortunately, due to the heterogeneity of the recipients and their multimorbidity, imaging procedures in the early phase after kidney transplantation are difficult and of limited use. We performed a study to evaluate the use of a contrast enhancer for US examination as a standardized method in the follow-up of kidney transplant recipients.The study included 40 recipients: 32 were examined on the 5th to 7th day following transplantation and 8 patients at the time when clinically suspicious findings occurred (acute rejection, tumor, acute tubular necrosis). Following the intravenous application of the contrast medium, pictures were taken during the arterial and parenchymatous phase and compared with conventional B-mode and power Doppler pictures of the same visual plane. Three examiners assessed different parameters of the transplant organ (max. vascularized area, suspected hematomas, tumors, rejection, acute tubular necrosis). Findings were confirmed by histological results of a biopsy if rejection, tumor, or acute tubular necrosis were suspected. Application of ultrasound contrast medium significantly increased visualization of the vascularized kidney area. Also, US findings in the follow-up after acute rejection therapy corresponded with the clinical course; 19 hematomas could be detected with contrast medium compared to only 9 without. With contrast medium a perfusion deficit was detectable in three patients compared to one patient with power Doppler US. Also, US contrast medium helped to detect tumor vascularization in two patients in whom conventional sonography suspected no abnormality. Ultrasound contrast medium enhancement is a reproducible, reliable, and easy to apply method which is superior to conventional sonography in the follow-up after kidney transplantation. This method is also helpful to detect and control acute rejections and to better visualize hematomas, deficits of perfusion, and tumors.

[Surgery for congestive heart failure--the role of computed tomography in the pre- and postoperative diagnostic evaluation]. / Chirurgie der Herzinsuffizienz -- Stellenwert der Computertomographie in der prä- und postoperativen Diagnostik.

The treatment of advanced, drug resistant congestive heart failure gains in importance in the field of cardiac surgery. Cardiac imaging for preoperative assessment and follow-up focuses on the determination of ventricular volumes and function as well as on the detection of postoperative complications. Computed tomography (CT) is highly accurate irrespective of the individual patient's anatomic situation, has a low examiner dependence and short examination time, does not require an arterial vascular access and can be performed in patients with metal implants. CT is the modality of choice in the follow-up of heart transplants to detect extracardiac and cardiac complications including coronary calcifications as an early sign of transplant vasculopathy. In addition, CT visualizes the elements of mechanical assist devices and can identify their possible local cardiac and mediastinal complications. CT can detect fibrolipomatous involution of the mobilized muscle flap in dynamic cardiomyoplasty and can depict fibrous reactions along the epicardial mesh implant in passive cardiac containment. Further indications include assessment of typical local postoperative complications, such as intrathoracic infection and mediastinal bleeding, intracardiac thrombus formation or pericardial effusion. CT is routinely used for evaluating bypass patency but is limited in assessing associated valve defects since it does not visualize flow.

[Value of electron beam tomography (EBT)]. / Wertigkeit der Elektronenstrahl-Computertomographie (EBT) -- II. Nichtkardiale Anwendungen und Strahlenexposition.

Electron beam tomography (EBT) has been scientifically evaluated to a much lesser degree for non-cardiac indications than for cardiac purposes. Therefore, four groups of investigators in Berlin (2), Mannheim and Munchen, which were supported by the Deutsche Forschungsgemeinschaft (DFG), included applications outside the heart in their evaluation of EBT technology. EBT has proven useful to look for pulmonary embolism and to assess other vessels (aorta, aortic branches, and intracranial arteries). Imaging of the lung parenchyma benefits from its intrinsic high contrast and from the fast data acquisition of EBT. Limited photon efficiency, higher radiation exposure, increased noise levels and other artifacts, however, markedly reduce the value of EBT for imaging of low contrast objects compared to conventional spiral CT and multislice CT (MSCT), compromising, in particular, the morphologic depiction of parenchymal abdominal organs and the brain. Consequently, scientific studies to further evaluate EBT for scanning of the brain and parenchymal abdominal organs were not pursued. Radiation exposure for non-cardiac EBT studies is up to three times higher than that for respective spiral CT studies, and in children EBT can only be advocated in select cases. Radiation exposure for the various prospectively triggered cardiac examination protocols of EBT is lower than that for conventional coronary angiography. Radiation exposure in cardiac multislice CT exceeds severalfold that of EBT, but the dose efficiency of EBT and MSCT are similar due to higher spatial resolution and less image noise of MSCT. In addition, modifications of MSCT (ECG pulsing) can further reduce radiation exposure to the level of EBT. Technical improvements of the EBT successor scanner "e-Speed" enable faster data acquisition at higher spatial resolution. Within comparative studies, the "e-Speed" will have to prove its value and competitiveness, particularly in comparison with multislice CT. After profound scientific assessment in a multicenter evaluation supported by the Deutsche Forschungsgemeinschaft (DFG) and regardless of the specific suitability of electron beam tomography for various cardiac and some non-cardiac indications, the investigators unanimously find the electron beam tomograph Evolution C150 XP not suitable as a whole body CT scanner.

Early postoperative ultrasound of kidney transplants: evaluation of contrast medium dynamics using time-intensity curves.

OBJECTIVE: To evaluate kidney recipients in the early posttransplant phase by semiquantitative analysis of the arterial arrival of ultrasound (US) contrast medium using time-intensity curves. PATIENTS AND METHODS: Twenty-two kidney recipients underwent US examination after intravenous bolus administration of 2.4 ml of US contrast medium (SonoVue, Bracco Altana) 5 to 7 days after transplantation. The examinations were performed with the Aplio US system (Toshiba) and a 3.5-MHz wideband transducer using contrast harmonic imaging at a low mechanical index of 0.1. Arterial arrival was documented digitally over 60 sec (image repetition rate: 10 images per sec) for subsequent evaluation of contrast medium kinetics in the main renal artery, interlobar artery, subcapsular area, and renal vein using the system's integrated time-intensity curve (TIC) software. The increase, decrease, and percentage enhancement factor were calculated from the curves. Four patients were excluded from analysis because of perirenal hematoma (n = 3) or a polar perfusion loss demonstrated by power Doppler (n = 1). RESULTS: Twelve of the remaining 18 patients assigned to the nonrejection group showed an uneventful clinical course. These had uniform TICs with an early and steep increase of similar magnitude in the main renal artery (11.7 +/- 4.5 intensity units/sec), interlobar artery (8.7 +/- 4.6 intensity units/sec), and subcapsular area (8.3 +/- 3.7 intensity units/sec) followed by a washout and subsequent plateau phase. Six patients showed histologically proven acute rejection on day 5 or 6 after transplantation (rejection group). This group had a delayed (time to peak in the subcapsular area: 32.9 +/- 8.3 sec in the rejection group versus 20.9 +/- 4.7 sec in the nonrejection group, p < 0.05) and smaller subcapsular percentage increase (41.2 +/- 21.9 % versus 114.4 +/- 59.8 %, p < 0.05). In the rejection group the subcapsular area (3.8 +/- 2.3 intensity units/sec) showed a less pronounced increase than the main renal artery (7.9 +/- 5.9 intensity units/sec) and interlobar artery (8.7 +/- 3.8 intensity units/sec). The RI in the rejection group was in the normal range at the time of contrast-enhanced US (day 5: 0.78 +/- 0.06) and increased to abnormal levels in the further course (day 7: 0.94 +/- 0.09). CONCLUSIONS: Quantitative determination of arterial arrival of an US contrast medium in the early phase after kidney transplantation is possible. This new US procedure might identify acute rejection earlier than conventional techniques.

Multislice CT coronary angiography: evaluation of an automatic vessel detection tool.

PURPOSE: To investigate the potential of a new detection tool for multislice CT (MSCT) coronary angiography with automatic display of curved multiplanar reformations and orthogonal cross-sections. MATERIALS AND METHODS: Thirty-five patients were consecutively enrolled in a prospective intention-to-diagnose study and examined using a MSCT scanner with 16 x 0.5 mm detector collimation and 400 ms gantry rotation time (Aquilion, Toshiba). A multisegment algorithm using up to four segments was applied for ECG-gated reconstruction. Automatic and manual detection of coronary arteries was conducted using the coronary artery CT protocol of a workstation (Vitrea 2, Version 3.3, Vital Images) to detect significant stenoses (> or = 50 %) in all segments of > or = 1.5 mm in diameter. Each detection tool was used by one reader who was blinded to the results of the other detection method and the results of conventional coronary angiography. RESULTS: The overall sensitivity, specificity, nondiagnostic rate, and accuracy of the automatic and manual approach were 90 vs. 94 %, 89 vs. 84 %, 6 vs. 6 %, and 89 vs. 88 %, respectively (p = n. s.). The vessel length detected with the automatic and manual approach were highly correlated for the left main/left anterior descending (143 +/- 30 vs. 146 +/- 24 mm, r = 0.923, p < 0.001), left circumflex (94 +/- 35 vs. 93 +/- 33 mm, r = 0.945, p < 0.001), and right coronary artery (145 +/- 36 vs. 144 +/- 37 mm, r = 0.925, p < 0.001). The time required to create reformations along the coronary arteries was significantly shorter with the automatic tool compared to the manual approach (203 +/- 77 vs. 391 +/- 104 sec, p < 0.005). In 90 % of the coronary branches automatic detection required less time than the manual approach. CONCLUSION: Automatic coronary vessel detection is feasible and reduces the time required to create reformations by a factor of approximately two without deteriorating the diagnostic accuracy.

[Technical success rate, peri-interventional complications and radiation exposure of the transarterial embolization for leiomyomas of the uterus]. / Technische Erfolgsrate, peri-interventionelle Komplikationen und Strahlenexposition der transarteriellen Embolisation bei Uterus myomatosus.

PURPOSE: To analyze the technical success rate, incidence and type of peri-interventional complications, and radiation exposure of uterine artery embolization (UAE) in symptomatic leiomyomas of the uterus. MATERIALS AND METHODS: This prospective study includes 75 patients consecutively treated with UAE from October 2000 through August 2002, with all interventions performed by the same radiologist. Technical success rate, interventional material, and incidence and type of peri-interventional complications (length of hospitalization) were recorded and categorized according to the definitions of the Society of Interventional Radiology (SIR). Fluoroscopy time (FT), dose-area product (DAP), and effective dose (ED) were determined for each intervention and the influence of the radiologist's experience on the radiation exposure analyzed. RESULTS: UAE was technically successful in 97.3 % of the cases. Peri-interventional complications occurred in 14.7 %. Four complications (5.3 %) were classified as major class C according to the SIR (post-embolization syndrome requiring prolonged drug treatment and hospitalization [n = 3] perforation of the uterine artery [n = 1]). None of the complications led to discontinuation of the intervention, subsequent surgical intervention, or permanent sequelae. FT decreased significantly (p < 0.05) until the 35th intervention. The median FT decreased from 18.8 min (13.4 - 28 min [25th to 75th percentile]) to 11.8 min (9.7 - 13.3 min [25th to 75th percentile]). The DAP decreased by 25.3 % to a median of 8.547 (6.527 - 11.590 cGy*cm (2) [25th to 75th percentile]). The median ED was 31.5 mSv from the 36th intervention onward. CONCLUSION: UAE has a high technical success rate with a low rate of peri-interventional complications. The study showed a statistically significant learning effect with a decrease in radiation exposure for the first 35 interventions. The effective dose of UAE is comparable to that of 1 to 2 small bowel enema.

[Diagnostic value of electron-beam computed tomography (EBT). I. Cardiac applications]. / Diagnostische Wertigkeit der Elektronenstrahl-Computertomographie (EBT). I. Kardiale Anwendungen.

Electron beam tomography (EBT) directly competes with other non-invasive imaging modalities, such as multislice computed tomography, magnetic resonance imaging, and echocardiography, in the diagnostic assessment of cardiac diseases. EBT is the gold standard for the detection and quantification of coronary calcium as a preclinical sign of coronary artery disease (CAD). Its standardized examination protocols and the broad experience with this method favor EBT. First results with multislice CT indicate that this new technology may be equivalent to EBT for coronary calcium studies. The principal value of CT-based coronary calcium measurements continues to be an issue of controversy amongst radiologists and cardiologists due to lack of prospective randomized trials. Coronary angiography with EBT is characterized by a high negative predictive value and, in addition, may be indicated in some patients with manifest CAD. It remains to be shown whether coronary angiography with multislice CT is reliable and accurate enough to be introduced into the routine work-up, to replace some of the many strictly diagnostic coronary catheterizations in Germany and elsewhere. Assessment of coronary stent patency with EBT is associated with several problems and in our opinion cannot be advocated as a routine procedure. EBT may be recommended for the evaluation of coronary bypasses to look for bypass occlusions and significant stenoses, which, however, can be equally well achieved with multislice CT. Quantification of myocardial perfusion with EBT could not replace MRI or other modalities in this field. EBT has proven to be accurate, reliable and in some instances equivalent to MRI, which is the gold standard for the quantitative and qualitative evaluation of cardiac function. Some disadvantages, not the least of which is the limited distribution of electron beam scanners, favor MRI for functional assessment of the heart.