Purpose: To validate a novel approach for accelerated four‐dimensional phase contrast MR imaging (4D PC‐MRI) with an extended range of velocity sensitivity. Materials and Methods: 4D PC‐MRI data were acquired with a radially undersampled trajectory (PC‐VIPR). A dual Venc (dVenc) processing algorithm was implemented to investigate the potential for scan time savings while providing an improved velocity‐to‐noise ratio. Flow and velocity measurements were compared with a flow pump, conventional 2D PC MR, and single Venc 4D PC‐MRI in the chest of 10 volunteers. Results: Phantom measurements showed excellent agreement between accelerated dVenc 4D PC‐MRI and the pump flow rate (R2 ≥ 0.97) with a three‐fold increase in measured velocity‐to‐noise ratio (VNR) and a 5% increase in scan time. In volunteers, reasonable agreement was found when combining 100% of data acquired with Venc = 80 cm/s and 25% of the high Venc data, providing the VNR of a 80 cm/s acquisition with a wider velocity range of 160 cm/s at the expense of a 25% longer scan. Conclusion: Accelerated dual Venc 4D PC‐MRI was demonstrated in vitro and in vivo. This acquisition scheme is well suited for vascular territories with wide ranges of flow velocities such as congenital heart disease, the hepatic vasculature, and others. J. Magn. Reson. Imaging 2012. © 2012 Wiley Periodicals, Inc.

Purpose To validate a novel approach for accelerated four-dimensional phase contrast MR imaging (4D PC-MRI) with an extended range of velocity sensitivity. Materials and Methods 4D PC-MRI data were acquired with a radially undersampled trajectory (PC-VIPR). A dual Venc (dVenc) processing algorithm was implemented to investigate the potential for scan time savings while providing an improved velocity-to-noise-ratio. Flow and velocity measurements were compared to a flow pump and conventional 2D PC MR and single Venc 4D PC-MRI in the chest of ten volunteers. Results Phantom measurements showed excellent agreement between accelerated dVenc 4D PC-MRI and the pump flow rate (R2≥0.97) with a threefold increase in measured velocity-to-noise-ratio (VNR) and a 5% increase in scan time. In volunteers, reasonable agreement was found when combining 100% of data acquired with Venc=80 cm/s and 25% of the high Venc data, providing the VNR of a 80 cm/s acquisition with a wider velocity range of 160 cm/s at the expense of a 25% longer scan. Conclusion Accelerated dual Venc 4D PC-MRI was demonstrated in vitro and in vivo. This acquisition scheme is well suited for vascular territories with wide ranges of flow velocities such as congenital heart disease, the hepatic vasculature, and others.

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Journal of Cardiovascular Magnetic Resonance 2009, 11(Suppl 1):O1Introduction: Prophylactic implantation of a cardioverter/ defibrillator (ICD) has been shown to reduce mortality in patients with chronic myocardial infarction (CMI) and an increased risk for life threatening ventricular arrhythmia (VA). The use of ICDs in this large patient population is still limited by high costs and possible adverse events including inappropriate discharges and progression of heart failure. VA is related to infarct size and seems to be related to infarct morphology. Contrast enhanced cardiovascular magnetic resonance imaging (ceCMR) can detect and quantify myocardial fibrosis in the setting of CMI and might therefore be a valuable tool for a more accurate risk stratification in this setting. Hypothesis: ceCMR can identify the subgroup developing VA in patients with prophylactic ICD implantation following MADIT criteria. Methods: We prospectively enrolled 52 patients (49 males, age 69 ± 10 years) with CMI and clinical indication for ICD therapy following MADIT criteria. Prior to implantation (36 ± 78 days) patients were investigated on a 1.5 T clinical scanner (Siemens Avanto © , Germany) to assess left ventricular function (LVEF), LV end-diastolic volume (LVEDV) and LV mass (sequence parameters: GRE SSFP, matrix 256 × 192, short axis stack; full LV coverage, no gap; slice thickness 6 mm). For quantitative assessment of infarct morphology late gadolinium enhancement (LGE) was performed including measurement of total and relative infarct mass (related to LV mass) and the degree of transmurality (DT) as defined by the percentage of transmurality in each scar. (sequence parameters: inversion recovery gradient echo; matrix 256 × 148, imaging 10 min after 0.2 μg/kg gadolinium DTPA; slice orientation equal to SSFP). MRI images were analysed using dedicated software (MASS © , Medis,

Purpose: The purpose of this study was to evaluate protocols for low dose CT (LDCT) for lung cancer screening on a Revolution CT (GE Healthcare; Waukesha, WI). Lung cancer the leading cause of cancer death for men and women, and more deaths are attributable to lung cancer than breast, colon and prostate cancers combined. Recently, the National Lung Screening Trial (NLST) showed LDCT screening resulted in a 20% reduction in lung cancer mortality and 6.7% in mortality from all causes [NEJM, 2011]. Methods: The protocols for this study (Table 1) were designed based on the following criteria: (1) CTDIvol ≤ 3.0 mGy (for an “average” person), (2) dose variation based on patient size, (3) the ability to scan the entire lung in a single breath, (4) adequate image quality for LCS including the ability to detect nodules ≥ 5mm. A chest phantom (Chest Phantom N1, Kyoto Kagaku Co., Ltd, Kyoto Japan) was scanned with three fat plate configurations (small, average and large) and six artificial nodules: solid (+100 HU; 5, 8, and 10 mm) and non‐solid (‐630 HU; 5, 8, and 10 mm). The nodules were inserted into the lung structure along the vessels. Each scan was repeated 5 times. The contrast to noise ratio (CNR) was measured in the 5 mm nodules as the figure of merit for detectability (Figure 1). The sizes of all nodules were measured using a manual distance tool. Results: All phantom images showed sufficient image quality for lung nodule detection. CNR values were all more than sufficient for nodule detection of the kind and size related to lung cancer screening (Figure 2). Nodule size measurements all showed accuracy within 0.3 mm (Figure 3). Conclusion: This phantom study shows the presented low‐dose protocols should meet the needs for LDCT Lung Cancer Screening. All authors are employees of GE Healthcare.