Jana Taron

Feasibility of CAIPIRINHA-Dixon-TWIST-VIBE for dynamic contrast-enhanced MRI of the prostate.

PURPOSE To evaluate the feasibility of a CAIPIRINHA-Dixon-TWIST (CDT)-VIBE sequence for improving image quality and temporal resolution in dynamic contrast-enhanced MRI (DCE-MRI) of the prostate. MATERIAL AND METHODS 44 male patients (age 63.9 ± 8.9 years) with clinically suspected prostate cancer underwent DCE-MRI at a 3T MRI scanner (Magnetom Skyra, Siemens Healthcare, Erlangen, Germany) using a CDT-VIBE sequence (spatial resolution=3×1.2×1.2mm(3), temporal resolution=5s, total scan duration=4:10 min) with body-weight-adapted administration of contrast agent (Gadobutrol, Bayer Healthcare, Berlin, Germany). To investigate effects on image quality, the same sequence was acquired three times per patient during the late phase: 1. with the same protocol as in the arterial phase (VS5), 2. without view-sharing (no view-sharing, NVS) using a 2-fold CAIPIRINHA acceleration R=2 (temporal resolution=15s, NVS15) and 3. NVS using a 6-fold CAIPIRINHA acceleration R=6 (temporal resolution=5s, NVS5). SNR and CNR were evaluated with the subtraction method. Image quality of the three sequences (VS5, NVS15, NVS5) was subjectively assessed by 2 blinded radiologists using a 5-point Likert scale (5 being excellent). Perfusion profiles of visually normal prostate and of malignant lesions as characterized by Wash-In, Wash-Out, time-to-peak (TTP) and initial area under the curve (iAUC) from the original datasets (temporal resolution=5s) and from datasets with a downsampled temporal resolution (15s) were compared. RESULTS In 20 of 44 included patients, potentially malignant lesions were identified in which 16 had histologically confirmed prostate cancer. SNR was highest for VS5 and NVS15, and lowest for NVS5 (p <.001). Concordantly, subjective image quality was comparable for VS5 and NVS15 (sum score 23.20 ± 1.03 vs 23.53 ± 1.34) and significantly lower for NVS5 (sum score 9.83 ± 2.32; p<.001). Perfusion parameters of macroscopically normal prostate tissue and suspect lesions differed significantly between original datasets and datasets with simulated lower temporal resolution, with the latter showing higher Wash-In (p=.002), lower Wash-Out (p=.003), higher Time-to-Peak (p<.001) and lower iAUC (p<.001). CONCLUSION CDT-VIBE can be readily exploited for DCE-MRI of the prostate preserving the diagnostic image quality while providing high temporal resolution for quantitative diagnostic assessment of enhancement curves in malignant lesions.

Simultaneous multislice diffusion‐weighted MRI of the liver: Analysis of different breathing schemes in comparison to standard sequences

To systematically evaluate image characteristics of simultaneous‐multislice (SMS)‐accelerated diffusion‐weighted imaging (DWI) of the liver using different breathing schemes in comparison to standard sequences.

Simultaneous multislice diffusion-weighted imaging in whole-body positron emission tomography/magnetic resonance imaging for multiparametric examination in oncological patients

ObjectivesThe aim of this study was to compare the diagnostic performance of simultaneous multislice diffusion-weighted imaging (DWI-SMS) with that of standard DWI (DWI-STD) in whole-body 3-T PET/MRI examination protocols in oncological patients.MethodsIn a phantom study, we evaluated the apparent diffusion coefficients (ADC) from the two techniques. In ten volunteers, we assessed ADC values in different organs. In 20 oncological patients, we evaluated subjective image quality (Likert scale, 5 indicating excellent) and artefacts in different body regions. We also rated the conspicuity and acquired the ADC values of PET-positive tumorous lesions.ResultsThe scan time for the whole-body DWI-SMS examinations was 40% shorter than the scan time for the DWI-STD examinations (84 s vs. 140 s per table position). The phantom and volunteer studies showed lower ADC values from DWI-SMS in the liver and muscle (psoas muscle 1.4 vs. 1.3). In patients, DWI-SMS provided poorer subjective image quality in the thoracoabdominal region (3.0 vs. 3.8, p = 0.02) and overall more artefacts (138 vs. 105). No significant differences regarding conspicuity and ADC values of lesions were found.ConclusionsDWI-SMS seems to provide reliable conspicuity and ADC values of tumorous lesions similar to those provided by DWI-STD. Therefore, although providing poorer image quality in certain regions, DWI-SMS can clearly reduce PET/MRI scan times in oncological patients.Key points• DWI-SMS can reduce PET/MRI scan times in oncological patients.• DWI-SMS provides reliable ADC values and good lesion conspicuity similar to those provided by DWI-STD.• DWI-SMS may provide poorer image quality in regions with low signal.

Feasibility of accelerated simultaneous multislice diffusion‐weighted MRI of the prostate

To assess the feasibility of simultaneous multislice (SMS) single‐shot echo‐planar‐imaging (EPI) for accelerated diffusion‐weighted imaging (DWI) of the prostate.

Self-gated 4D-MRI of the liver: Initial clinical results of continuous multiphase imaging of hepatic enhancement

To evaluate the feasibility of a self‐gated free‐breathing volume‐interpolated breath‐hold examination (VIBE) sequence using compressed sensing (CS) for contrast‐enhanced multiphase liver MRI.

Background parenchymal enhancement in pregnancy-associated breast cancer: a hindrance to diagnosis?

PurposeThe purpose of this study is to investigate the detectability of pregnancy-associated breast cancer (PABC) in lactating glandular tissue on magnetic resonance imaging (MRI) by using pre- and post-contrast acquisitions and their derived postprocessed images and compare these results to ultrasound (US) and mammography (MG).Materials and methodsWe reviewed the electronic database for women with PABC and existing breast MRI. MR images (T2-weighted short inversion-recovery sequence [STIR], dynamic contrast-enhanced T1-weighted gradient echo sequence and postprocessed subtraction images [early post-contrast minus pre-contrast]) were retrospectively evaluated (image quality, parenchymal/tumour enhancement kintetics, tumour size and additional lesions). Supplemental subtraction images (latest post-contrast minus early post-contrast) to reduce plateau enhancement were additionally calculated and tumour conspicuity and size were measured. Findings were compared to US and MG reports.ResultsNineteen patients (range 27–42 years) were included. Background parenchymal enhancement (BPE) was minimal (n=1), mild (n=3), moderate (n=7) and marked (n=8) with kinetics measured plateau (n=8), continuous (n=10) and not quantifiable (n=1). Tumour kinetics presented wash-out (n=17) and plateau (n=2). Eighteen of nineteen tumours were identified on the supplemental subtraction images. All tumours were visible on US; 12/19 were visible on MG (63.2%). MRI detected additional malignant lesions in two patients.ConclusionDespite high BPE of the lactating breast, MRI securely detects carcinomas and identifies satellite lesions. By using supplemental subtraction images, background enhancement can be eliminated to facilitate diagnosis. US remains a reliable diagnostic tool, but additional MRI is recommended to rule out satellite/contralateral lesions. MG interpretations can be difficult due to high parenchymal density.Key Points• Despite high background enhancement, MRI of the breast confidently detects carcinomas and identifies further lesions in the lactating breast.• By using supplemental subtraction images, background enhancement in the lactating breast can be eliminated to facilitate diagnosis.• US remains a reliable diagnostic tool. Mammography can be limited due to extremely dense breast tissue related to lactation.

Scan time reduction in diffusion-weighted imaging of the pancreas using a simultaneous multislice technique with different acceleration factors: How fast can we go?

ObjectivesTo investigate the feasibility of simultaneous multislice-accelerated diffusion-weighted imaging (sms-DWI) of the pancreas with different acceleration factors and its influence on image quality, acquisition time and apparent diffusion coefficients (ADCs) in comparison to conventional sequences.MethodsDWI of the pancreas was performed at 1.5T in ten healthy volunteers and 20 patients with sms-accelerated echo-planar DWI using two different sms-acceleration factors of 2 and 3 (sms2/3-DWI). These DWI sequences were compared to conventional DWI (c-DWI) in terms of image quality parameters (5-point Likert scale) and ADC measurements.Resultsc-DWI and sms2-DWI offered equivalently high overall image quality (4 [1; 5]) with scan time reduction to one-third (c-DWI: 173 s, sms2-DWI: 56 s). Sms3-DWI showed significantly poorer overall image quality (3 [1; 5]; p < 0.0001). ADC values were significantly lower in sms3-DWI compared to c-DWI in the pancreatic body and tail (body: c-DWI 1.4 x 10-3 mm2/s, sms3-DWI 1.0 x 10-3 mm2/s, p = 0.028; tail: c-DWI 1.3 x 10-3 mm2/s and sms3-DWI 1.0 x 10-3 mm2/s, p = 0.014).ConclusionsAccelerated multislice DWI of the pancreas offers high image quality with a substantial reduction of acquisition time. Lower ADC values in multislice DWI should be considered in diagnostic reading.Key Points• Simultaneous multislice-accelerated diffusion-weighted imaging (sms-DWI) promises scan time minimisation.• Sms-DWI of the pancreas offers diagnostic image quality in volunteers and patients.• Sms-DWI with an acceleration factor of 2 offers high image quality.• Higher acceleration factors in sms-DWI do not provide sufficient diagnostic image quality.• ADC values may be lower in sms-DWI.

Added value of diffusion-weighted imaging in hepatic tumors and its impact on patient management

BackgroundTo investigate the added diagnostic value of diffusion-weighted imaging (DWI) of the liver and its impact on therapy decisions in patients with hepatic malignancy.MethodsInterdisciplinary gastrointestinal tumorboard cases concerning patients with hepatic malignancies discussed between 11/2015 and 06/2016 were included in this retrospective, single-center study. Two radiologists independently reviewed the respective liver MR-examination first without, then with DWI. The readers were blinded regarding number, position and size of hepatic malignancies. Cases in which DWI revealed additional findings concerning the hepatic tumor status as compared to conventional sequences alone were presented to experienced members of the interdisciplinary tumor board. In this retrospective setting changes in treatment decisions based on these additional findings in the DWI sequences were recorded.ResultsA total of 87 patients were included. DWI revealed additional findings in 12 patients (13,8%). These new findings had a direct effect on the therapy in 8 patients (9,2%): In 6 patients (6,9%) the surgical/interventional treatment was adapted (n = 5: extended resection, n = 1: with transarterial chemoembolization of a single hepatocellular carcinoma only detectable in DWI); 2 patients (2,3%) received systemic therapy (n = 1: neo-adjuvant, n = 1: palliative) based on the additional findings in DWI. In 4 patients (4.6%) additional DWI findings did not affect the therapeutic decision.ConclusionsDWI is a relevant diagnostic tool in oncologic imaging of the liver. By providing further information regarding tumor load in hepatic malignancies it can lead to a significant change in treatment.

Clinical Robustness of Accelerated and Optimized Abdominal Diffusion-Weighted Imaging

Objectives The aim of this study was to assess the robustness of an accelerated and optimized diffusion-weighted sequence in clinical routine abdominal imaging using the simultaneous multislice (SMS) technique for scan time reduction and 3-dimensional (3D) diagonal diffusion mode to optimize image quality. Materials and Methods One hundred fifty consecutive patients received clinically indicated magnetic resonance imaging for abdominal imaging including an optimized SMS diffusion-weighted sequence (DWIOPT: diffusion mode 3D diagonal; SMS factor 2; scan time 1:44 minutes). A subgroup of 41 patients additionally received a standard diffusion-weighted sequence as reference (DWISTD: diffusion mode 4-scan trace; scan time 2:35 minutes). Qualitative and quantitative image parameters of DWISTD and DWIOPT were assessed and compared interindividually within the subgroup using dedicated statistics. Results In all patients, image quality ratings in DWIOPT were rated very high (overall image quality, 4.6 [4–5]; contour sharpness of right/left hepatic lobe, 4.6 [4–5]/4.4 [4–5]; and lesion conspicuity, 4.5 [4.5–5]). Interindividually, DWIOPT proved superior to DWISTD in comparison of overall image quality (4.6 [4.6–4.7] vs 4.2 [4.1–4.2]; P = 0.025) and contour sharpness of the right/left hepatic lobe (4.6 [4.5–4.7]/4.3 [4.0–4.3] vs 4.3 [4.1–43]/4.0[3.0–4.0]; each P = 0.045); lesion conspicuity was comparable in DWIOPT and DWISTD (4.0 [4.8–5] vs 4.4 [4–5]; P = 0.461), and apparent diffusion coefficient (ADC) values showed no statistically significant difference (ADCOPT vs ADCSTD: right hepatic lobe, P = 0.084; kidney, P = 0.445). Interreader agreement was substantial with a kappa value of 0.78 (P < 0.001). Conclusions Diffusion-weighted imaging of the abdomen can be considerably accelerated and optimized integrating the SMS technique and a 3D diagonal diffusion mode. In a large patient cohort, this approach proved of superior image quality while maintaining similar ADC values compared with standard DWI. This technique seems applicable for daily clinical routine.