Miriam Reichert

Publications of Miriam Reichert

• Dual-energy CT angiography of the lungs: comparison of test bolus and bolus tracking techniques for the determination of scan delay.

  Authors: Thomas Henzler, Mathias Meyer, Miriam Reichert, Radko Krissak, John W Nance, Stefan Haneder, Stefan O Schoenberg, Christian Fink

  European journal of radiology. 01/2012; 81(1):132-8.

  To prospectively compare test bolus and bolus tracking for the determination of scan delay of pulmonary dual-energy CT angiography in patients with suspected pulmonary embolism. 60 consecutiveTo prospectively compare test bolus and bolus tracking for the determination of scan delay of pulmonary dual-energy CT angiography in patients with suspected pulmonary embolism. 60 consecutive patients referred for CTA for exclusion of PE were randomized either into a test bolus group or into a bolus tracking group. All exams were performed on a 64-channel dual source CT scanner. A standard single-acquisition dual-energy CTA was performed after injection of 100ml Iomeprol 400 followed by a saline chaser of 4 ml/s. The scan delay was determined using either test bolus (n=30) or bolus tracking (n=30). Test bolus was performed using an additional 20 ml Iomeprol 400 injected with a rate of 4 ml/s during acquisition of a series of dynamic low-dose monitoring scans followed by injection of a saline bolus of 20 ml using the same flow rate. For DECT angiography of the lungs 100ml Iomeprol 400 was injected with an injection rate of 4 ml/s followed by a saline chaser of 20 ml using the same flow rate. Attenuation profiles of different vascular segments (pulmonary arteries, pulmonary parenchyma, aorta, all 4 heart chambers) were measured to evaluate the timing techniques. Overall image quality of dual-energy "perfusion" maps and virtual 120 kV CTA images was evaluated by two radiologists regarding the present of artifacts. In all patients an adequate and homogeneous contrast enhancement of more than 400 Hounsfield units (HU) was achieved in the different vascular districts. No statistically significant difference between test bolus and bolus tracking was found regarding vessel attenuation or overall image quality. A homogeneous opacification of the different vascular territories and the pulmonary parenchyma as well as a sufficient image quality can be achieved with either bolus tracking or test bolus techniques.

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• Venous thromboembolism: additional diagnostic value and radiation dose of pelvic CT venography in patients with suspected pulmonary embolism.

  Authors: Miriam Reichert, Thomas Henzler, Radko Krissak, Paul Apfaltrer, Kurt Huck, Karen Buesing, Tim Sueselbeck, Stefan O Schoenberg, Christian Fink

  European journal of radiology. 04/2011; 80(1):50-3.

  To assess the additional diagnostic value of indirect CT venography (CTV) of the pelvis and upper thighs performed after pulmonary CT angiography (CTA) for the diagnosis of venous thromboembolismTo assess the additional diagnostic value of indirect CT venography (CTV) of the pelvis and upper thighs performed after pulmonary CT angiography (CTA) for the diagnosis of venous thromboembolism (VTE). In a retrospective analysis, the radiology information system entries between January 2003 and December 2007 were searched for patients who received pulmonary CTA and additional CTV of the pelvis and upper thighs. Of those patients, the radiology reports were reviewed for the diagnosis of pulmonary embolism (PE) and deep venous thrombosis (DVT) in the pelvic veins and veins of the upper thighs. In cases with an isolated pelvic thrombosis at CTV (i.e. which only had a thrombosis in the pelvic veins but not in the veins of the upper thigh) ultrasound reports were reviewed for the presence of DVT of the legs. The estimated radiation dose was calculated for pulmonary CTA and for CTV of the pelvis. In the defined period 3670 patients were referred to our institution for exclusion of PE. Of those, 642 patients (353 men, 289 women; mean age, 65±15 years, age range 18-98 years) underwent combined pulmonary CTA and CTV. Among them, PE was found in 227 patients (35.4%). In patients without PE CTV was negative in all cases. In patients with PE, CTV demonstrated pelvic thrombosis in 24 patients (3.7%) and thrombosis of the upper thighs in 43 patients (6.6%). Of those patients 14 (2.1%) had DVT in the pelvis and upper thighs. In 10 patients (1.5%) CTV showed an isolated pelvic thrombosis. Of those patients ultrasound reports were available in 7 patients, which revealed DVT of the leg veins in 5 cases (1%). Thus, the estimated prevalence of isolated pelvic thrombosis detected only by pelvic CTV ranges between 1-5/642 patients (0.1-0.7%). Radiation dose ranges between 4.8 and 9.7 mSv for additional CTV of the pelvis. CTV of the pelvis performed after pulmonary CTA is of neglectable additional diagnostic value for the detection of VTE, because the additional radiation dose is high and isolated pelvic DVT is very rare. Venous imaging of the legs (preferably by radiation-free ultrasound) is sufficient for the diagnosis of underlying DVT in patients with suspected PE.

• Triple-rule-out dual-source CT angiography of patients with acute chest pain: Dose reduction potential of 100kV scanning.

  Authors: Radko Krissak, Thomas Henzler, Anne Prechel, Miriam Reichert, Joachim Gruettner, Tim Sueselbeck, Stefan O Schoenberg, Christian Fink

  European journal of radiology. 12/2010;

  PURPOSE: To investigate the dose reduction potential of low kV triple-rule-out dual-source CT angiography (TRO-CTA) in non-obese (BMI≤25kg/m(2)) patients with acute chest pain. MATERIALS AND METHODS:PURPOSE: To investigate the dose reduction potential of low kV triple-rule-out dual-source CT angiography (TRO-CTA) in non-obese (BMI≤25kg/m(2)) patients with acute chest pain. MATERIALS AND METHODS: Sixty consecutive patients were randomly assigned to two different retrospectively ECG-gated TRO-CTA protocols in this prospective trial: Thirty patients were examined with a 120-kV standard protocol (320 reference mAs with automatic tube current modulation, automatically adapted pitch and ECG-pulsing) and served as the control group (group 1), an otherwise identical 100kV protocol was used in the other thirty patients (group 2) for a radiation dose reduction. Subjective image quality was assessed on a 5 point scale (1: excellent, 5: non-diagnostic) by two blinded observers. Quantitative image analysis assessed vascular attenuation, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in different vascular segments. The effective dose was calculated from the dose length product (DLP) using a conversion coefficient of 0.017mSvmGy(-1)cm(-1). RESULTS: There was no significant difference of age, BMI, heart rate, pitch or scan length between both patient groups. Subjective image quality was rated similar in both groups (group 1: 1.2±0.4, group 2: average score=1.3±0.5). Vessel attenuation was significantly higher in group 2 than in group 1 (ascending aorta: 456±83 HU vs. 370±78 HU, p<0.001; pulmonary artery: 468±118 HU vs. 411±91 HU, p=0.03; left coronary artery: 437±110 HU vs. 348±89 HU, p<0.001), however, there was no significant difference in SNR (13.2±7.6 vs. 14.5±7.5, p=0.49) or CNR (13.8±6.6 vs. 15.9±7.7, p=0.25). The effective radiation dose of the 100kV protocol was significantly lower (9.6±3.2mSv vs. 18.1±9.4mSv, p<0.0001). CONCLUSION: TRO-CTA with 100kV is feasible in non-obese patients and results in diagnostic image quality and significantly reduced radiation dose.

• Enhanced visualization of lung vessels for diagnosis of pulmonary embolism using dual energy CT angiography.

  Authors: Radko Krissak, Thomas Henzler, Miriam Reichert, Bernhard Krauss, Stefan O Schoenberg, Christian Fink

  Investigative radiology. 06/2010; 45(6):341-6.

  To evaluate a software algorithm highlighting vascular iodine distribution in dual energy (DE) computed tomography angiography (CTA) for the diagnosis of pulmonary embolism (PE). Pulmonary DE-CTA ofTo evaluate a software algorithm highlighting vascular iodine distribution in dual energy (DE) computed tomography angiography (CTA) for the diagnosis of pulmonary embolism (PE). Pulmonary DE-CTA of 16 patients with PE and 16 patients without PE were analyzed using a software algorithm highlighting vascular iodine distribution. The algorithm color-codes lung vessels depending on their local iodine distribution on a 2-color scale. The diagnostic performance of the software for the detection of PE was assessed on patient and segmental basis by consensus reading of 2 blinded radiologists. The reading of the standard CTA data by an independent third radiologist and clinical follow-up served as the standard of reference for the diagnosis of PE. Of 576 analyzed segments CTA revealed 88 diseased lung segments with 1 or more emboli. The software correctly highlighted 62 segments as positive. Twenty-six segments with PE were not highlighted. Seventy-five segments were highlighted false positive. All 16 patients with PE were identified as positive, but 1 of these patients had no true positive finding on a segmental basis and was therefore classified as false negative. Twenty-three segments in 8 patients without PE were highlighted as positive. Sensitivity, specificity, positive predictive value, and negative predictive value of the software algorithm were 93.8%, 50%, 65.2%, 88.9% per patient and 70.5%, 84.6%, 45.3%, 94.1% per segment, respectively. Additional review of the DE-CTA with a dedicated software algorithm highlighting the vascular iodine distribution has a high negative predictive value important for exclusion of segmental PE.

• Volumetric analysis of pulmonary CTA for the assessment of right ventricular dysfunction in patients with acute pulmonary embolism.

  Authors: Thomas Henzler, Radko Krissak, Miriam Reichert, Tim Sueselbeck, Stefan O Schoenberg, Christian Fink

  Academic radiology. 03/2010; 17(3):309-15.

  To retrospectively determine the value of a volumetric ventricle analysis for the assessment of right ventricular dysfunction in patients with suspected pulmonary embolism (PE) by using image dataTo retrospectively determine the value of a volumetric ventricle analysis for the assessment of right ventricular dysfunction in patients with suspected pulmonary embolism (PE) by using image data from non-electrocardiographically (ECG)-gated multidetector computed tomography angiography (CTA). Hypothesizing that the presence of PE and the embolus location correlated with right ventricular dysfunction, we retrospectively analyzed 100 non-ECG-gated pulmonary CTA datasets of patients with central, peripheral, and without PE. Right ventricle/left ventricle (RV/LV) diameter ratio measured in transverse sections (RV/LV(trans)), four-chamber view (RV/LV(4ch)), and RV/LV volume ratio (RV/LV(vol)) were assessed on CT images. The results were correlated with the embolus location, the 30-day mortality rate, and the necessity of intensive care treatment. All CT parameters showed statistically significant differences between all patients groups depended on embolus location. The receiver operating characteristic analysis RV/LV(vol) showed the strongest discriminatory power to differ between patients with central and without PE and between patients with central and peripheral PE (central PE vs. no PE: RV/LV(vol) = 0.932, RV/LV(trans) = 0.880, and RV/LV(4ch) = 0.811, central PE vs. peripheral PE: RV/LV(vol) = 0.950, RV/LV(trans) = 0.849, and RV/LV(4ch) = 0.881), indicating a correlation with embolus location predisposing for RVD. For the identification of high-risk patients with PE all three CT parameters showed statistically significant values (P < .0001), whereas in the receiver operating characteristic analysis, RV/LV(vol) had the strongest discriminatory power (RV/LV(vol) = 0.819, RV/LV(trans) = 0.799, and RV/LV(4ch) = 0.758). Ventricle volumetry of non-ECG-gated CTA allows the assessment of right ventricular dysfunction in patients with acute PE. Compared to unidimensional measurements, a volumetric analysis seems to be slightly superior to identify high-risk patients with adverse clinical outcome. However, the method is more time consuming and requires dedicated software tools compared to unidimensional parameters, which is disadvantageous in an emergency setting.