Babs M. F. Hendriks

Coronary CT angiography using low concentrated contrast media injected with high flow rates: Feasible in clinical practice.

PURPOSE Aim of this study was to test the hypothesis that peak injection pressures and image quality using low concentrated contrast media (CM) (240 mg/mL) injected with high flow rates will be comparable to a standard injection protocol (CM: 300 mg/mL) in coronary computed tomographic angiography (CCTA). MATERIAL AND METHODS One hundred consecutive patients were scanned on a 2nd generation dual-source CT scanner. Group 1 (n=50) received prewarmed Iopromide 240 mg/mL at an injection rate of 9 mL/s, followed by a saline chaser. Group 2 (n=50) received the standard injection protocol: prewarmed Iopromide 300 mg/mL; flow rate: 7.2 mL/s. For both protocols, the iodine delivery rate (IDR, 2.16 gI/s) and the total iodine load (22.5 gI) were kept identical. Injection pressure (psi) was continuously monitored by a data acquisition program. Contrast enhancement was measured in the thoracic aorta and all proximal and distal coronary segments. Subjective and objective image quality was evaluated between both groups. RESULTS No significant differences in peak injection pressures were found between both CM groups (121 ± 5.6 psi vs. 120 ± 5.3 psi, p=0.54). Flow rates of 9 mL/s were safely injected without any complications. No significant differences in contrast-to-noise ratio, signal-to-noise ratio and subjective image quality were found (all p>0.05). No significant differences in attenuation levels were found in the thoracic aorta and all segments of the coronary arteries (all p>0.05). CONCLUSION Usage of low iodine concentration CM and injection with high flow rates is feasible. High flow rates (9 mL/s) of Iopromide 240 were safely injected without complications and should not be considered a drawback in clinical practice. No significant differences in peak pressure and image quality were found. This creates a doorway towards applicability of a broad variety in flow rates and IDRs and subsequently more individually tailored injection protocols.

DWI for Assessment of Rectal Cancer Nodes After Chemoradiotherapy: Is the Absence of Nodes at DWI Proof of a Negative Nodal Status?

OBJECTIVE When considering organ preservation in patients with rectal cancer with good tumor response, assessment of a node-negative status after chemoradiation therapy (CRT) is important. DWI is a very sensitive technique to detect nodes. The study aim was to test the hypothesis that the absence of nodes at DWI after CRT is concordant with a ypN0 status. MATERIALS AND METHODS A retrospective study was performed of 90 patients with rectal cancer treated with CRT followed by restaging MRI at 1.5 T, including DWI (highest b value, 1000 s/mm2). Two independent readers counted the number of nodes visible in the mesorectal compartment on DW images obtained after CRT. The number of nodes on DWI (0 vs ≥ 1) was compared with the number of metastatic nodes at histopathology or long-term clinical follow-up (yN0 vs yN-positive status). RESULTS Seventy-one patients had a yN0 status, and 19 had a yN-positive status. For 10 patients, no nodes were observed at DWI, which was concordant with a yN0 status in 100% of cases. In the other 61 patients with a yN0 status, the median number of nodes detected at DWI was three (range, 1-17 nodes). To differentiate between yN0 and yN-positive status, sensitivity was 100%, specificity was 14%, the positive predictive value was 24%, and the negative predictive value was 100%. CONCLUSION Although the absence of nodes at DWI is not a frequent finding, it appears to be a reliable predictor of yN0 status after CRT in patients with rectal cancer. DWI may thus be a helpful adjunct in assessing response after CRT and may help select patients for organ-saving treatment.

Individualized CT Angiography Protocols for the Evaluation of the Aorta: A Feasibility Study

PURPOSE Ionizing radiation and iodinated contrast media are potential drawbacks to repetitive follow-up CT angiography in current practice. The aim of the present study was to optimize radiation dose and contrast agent volume by using individualized CT angiography protocols. MATERIALS AND METHODS Eighty consecutive patients referred for CT angiography of the whole aorta were prospectively evaluated. Patients were divided into groups of patients with a body mass index (BMI) < 28 kg/m(2) (group 1; n = 50) and those with a BMI ≥ 28 kg/m(2) (group 2; n = 30). A control group consisted of 50 consecutive patients who were retrospectively evaluated. CT angiography parameters on a second-generation dual-source scanner were 128 × 0.6-mm collimation, pitch of 0.9, rotation time of 0.33 seconds, tube voltages of 80/100/120 kVp (group 1/group 2/control), reference tube current of 400 mA, and image reconstruction at 1-mm/0.8-mm slice thickness (kernels, B30f [control] and I30f/strength 3 [groups 1/2]). The control group received 120 mL of contrast agent (300 mgI/mL) at 4.8 mL/s; groups 1 and 2 received 44 mL and 53 mL at 3.3 mL/s and 4 mL/s, respectively. Effective dose was evaluated for each patient. Image quality was determined by qualitative image analysis at the levels of the thoracic, abdominal, and pelvic aorta as nondiagnostic, diagnostic, good, or excellent, and quantitative image analysis was performed, including attenuation values and contrast-to-noise ratio (CNR). RESULTS Mean effective radiation dose values for CT angiography of the aorta were 3.7 mSv ± 0.7 in group 1, 6.7 mSv ± 1.4 in group 2, and 8.7 mSv ± 1.9 in the control group (P < .001). Mean attenuation values and CNR levels were 334 HU ± 66 and 16 ± 8, respectively, in group 1, 277 HU ± 56 and 14 ± 5 in group 2, and 305 HU ± 77 and 11 ± 4 in the control group. CONCLUSIONS Iterative reconstruction algorithms resulted in 23%-57% less radiation in combination with 55%-63% less contrast agent volume compared with standard CT protocols.

Patient Comfort During Contrast Media Injection in Coronary Computed Tomographic Angiography Using Varying Contrast Media Concentrations and Flow Rates: Results From the EICAR Trial.

PurposePain sensation and extravasation are potential drawbacks of contrast media (CM) injection during computed tomographic angiography. The purpose was to evaluate safety and patient comfort of higher flow rates in different CM protocols during coronary computed tomographic angiography. MethodsTwo hundred consecutive patients of a double-blind randomized controlled trial (NCT02462044) were analyzed. Patients were randomized to receive 94 mL of prewarmed iopromide 240 mg I/mL at 8.3 mL/s (group I), 75 mL of 300 mg I/mL at 6.7 mL/s (group II), or 61 mL of 370 mg I/mL at 5.4 mL/s (group III), respectively. Iodine delivery rate (2.0 g I/s) and total iodine load (22.5 g I) were kept identical. Outcome was defined as intravascular enhancement, patient comfort during injection, and injection safety, expressed as the occurrence of extravasation. Patients completed a questionnaire for comfort, pain, and stress during CM injection. Comfort was graded using a 5-point scale, 1 representing “very bad” and 5 “very well.” Pain was graded using a 10-point scale, 0 representing “no pain” and 10 “severe pain.” Stress was graded using a 5-point scale, 1 representing “no stress” and 5 “unsustainable stress.” ResultsMean enhancement levels within the coronary arteries were as follows: 437 ± 104 Hounsfield units (HU) (group I), 448 ± 111 HU (group II), and 447 ± 106 HU (group III), with P ≥ 0.18. Extravasation occurred in none of the patients. Median (interquartile range) for comfort, pain, and stress was, respectively, 4 (4–5), 0 (0–0), and 1 (1–2), with P ≥ 0.68. ConclusionsHigh flow rates of prewarmed CM were safely injected without discomfort, pain, or stress. Therefore, the use of high flow rates should not be considered a drawback for CM administration in clinical practice.

Personalization of injection protocols to the individual patient’s blood volume and automated tube voltage selection (ATVS) in coronary CTA

Purpose The aim was to assess personalised contrast media (CM) protocols—based on patient’s blood volume (BV) and automated tube voltage selection (ATVS)—in coronary computed tomography angiography (CCTA). Methods A total of 114 consecutive patients received an ECG-triggered or ECG-gated helical scan on a 3rd-generation dual-source CT with 70-120kV (ATVS) and 330mAsqual.ref. CM was adapted to BV, scan time (s) and kV. Image quality (IQ) was assessed in a 17-segment coronary model using attenuation values (HU), contrast-to-noise (CNR), signal-to-noise ratio (SNR) (objective IQ) and a Likert scale (subjective IQ: 1 = poor/2 = sufficient/3 = good/4 = excellent). ig Results Patient distribution was: n = 60 for 70kV, n = 37 80kV and n = 17 90kV. Mean BV was 5.4±0.6L for men and 4.1±0.6L for women. Mean CM volume (300 mg I/mL) and flow rate were: 30.9±6.4mL and 3.3±0.5mL/s (70kV); 40.8±7.1mL and 4.5±0.6mL/s (80kV); 53.6±8.6mL and 5.7±0.6mL/s (90kV). Overall mean HU was >300HU in 98.2% (112/114) of patients. Overall mean attenuation was below 300HU in two scans (70kV) due to late scan timing. Of 1.661 segments, 95.4% was assessable. Mean CNR was 14±4(70kV), 13±3(80kV) and 14±4(90kV); mean SNR was 10±2(both 70kV+80kV) and 9±2(90kV). Objective IQ was comparable between kV settings, protocols and sex. Subjective IQ was diagnostic in all scans and excellent-sufficient in 95.4% of segments. Conclusions Personalisation of CCTA CM injection protocols to BV and ATVS is a promising technique to tailor CM administration to the individual patient, while maintaining diagnostic IQ.

Aortic root evaluation prior to transcatheter aortic valve implantation—Correlation of manual and semi-automatic measurements

Background Pre-procedural TAVI planning requires highly sophisticated and time-consuming manual measurements performed by experienced readers. Semi-automatic software may assist with partial automation of assessment of multiple parameters. The aim of this study was to evaluate differences between manual and semi-automatic measurements in terms of agreement and time. Methods One hundred and twenty TAVI candidates referred for the retrospectively ECG-gated CTA (2nd and 3rd generation dual source CT) were evaluated. Fully manual and semi-automatic measurements of fourteen aortic root parameters were assessed in the 20% phase of the R-R interval. Reading time was compared using paired samples t-test. Inter-software agreement was calculated using the Intraclass correlation coefficient (ICC) in a 2-way mixed effects model. Differences between manual and semi-automatic measurements were evaluated using Bland-Altman analysis. Results The time needed for evaluation using semi-automatic assessment (3 min 24 s ± 1 min 7 s) was significantly lower (p<0.001) compared to a fully manual approach (6 min 31 sec ± 1 min 1 sec). Excellent inter-software agreement was found (ICC = 0.93 ± 0.0; range:0.90–0.95). The same prosthesis size from manual and semi-automatic measurements was selected in 92% of cases, when sizing was based on annular area. Prosthesis sizing based on annular short diameter and perimeter agreed in 99% and 96% cases, respectively. Conclusion Use of semi-automatic software in pre-TAVI evaluation results in comparable results in respect of measurements and selected valve prosthesis size, while necessary reading time is significantly lower.

Do CTA measurements of annular diameter, perimeter and area result in different TAVI prosthesis sizes?

Incorrect prosthesis size has direct impact on patient outcome after transcatheter aortic valve implantation (TAVI) procedure. Currently, annular diameter, area or perimeter may be used for prosthesis size selection. The aim was to evaluate whether the use different annular dimensions would result in the selection of different prosthesis sizes, when assessed in the same TAVI-candidate during the same phase of a cardiac cycle. Fifty consecutive TAVI-candidates underwent retrospectively ECG-gated computed tomography angiography (CTA). Aortic root dimensions were assessed in the 20% phase of the R–R interval. Annular short diameter, perimeter and area were used to select the prosthesis size, based on the industry recommendations for a self-expandable (Medtronic CoreValve; MCV) and balloon-expandable (Edwards Sapien XT Valve; ESV) valve. Complete agreement on selected prosthesis size amongst all three annular dimensions was observed in 62% (31/50; ESV) and 30% (15/50; MCV). Short aortic annulus measurement resulted in a smaller prosthesis size in 20% (10/50; ESV) and in 60% of cases (30/50; MCV) compared to the size suggested by both annular perimeter and area. In 18% (9/50; ESV) and 10% of cases (5/50; MCV) a larger prosthesis would have been selected based on annular perimeter compared to annular diameter and area. Prosthesis size derived from area was always in agreement with at least one other parameter in all cases. Aortic annulus area appears to be the most robust parameter for TAVI-prosthesis size selection, regardless of the specific prosthesis size. Short aortic annulus diameter may underestimate the prosthesis size, while use of annular perimeter may lead to size overestimation in some cases.