Low contrast media volume in pre-TAVI CT examinations

Abstract

PurposeTo evaluate image quality using reduced contrast media (CM) volume in pre-TAVI assessment.MethodsForty-seven consecutive patients referred for pre-TAVI examination were evaluated. Patients were divided into two groups: group 1 BMI < 28 kg/m2 (n = 29); and group 2 BMI > 28 kg/m2 (n = 18). Patients received a combined scan protocol: retrospective ECG-gated helical CTA of the aortic root (80kVp) followed by a high-pitch spiral CTA (group 1: 70 kV; group 2: 80 kVp) from aortic arch to femoral arteries. All patients received one bolus of CM (300 mgI/ml): group 1: volume = 40 ml; flow rate = 3 ml/s, group 2: volume = 53 ml; flow rate = 4 ml/s. Attenuation values (HU) and contrast-to-noise ratio (CNR) were measured at the levels of the aortic root (helical) and peripheral arteries (high-pitch). Diagnostic image quality was considered sufficient at attenuation values > 250HU and CNR > 10.ResultsDiagnostic image quality for TAVI measurements was obtained in 46 patients. Mean attenuation values and CNR (HU ± SD) at the aortic root (helical) were: group 1: 381 ± 65HU and 13 ± 8; group 2: 442 ± 68HU and 10 ± 5. At the peripheral arteries (high-pitch), mean values were: group 1: 430 ± 117HU and 11 ± 6; group 2: 389 ± 102HU and 13 ± 6.ConclusionCM volume can be substantially reduced using low kVp protocols, while maintaining sufficient image quality for the evaluation of aortic root and peripheral access sites.Key points• Image quality could be maintained using low kVp scan protocols.• Low kVp protocols reduce contrast media volume by 34–67 %.• Less contrast media volume lowers the risk of contrast-induced nephropathy.

Radiation Dose Reduction in Preprocedural CT Imaging for TAVI/TAVR Using a Novel 3-Phase Protocol: A Single Institution’s Experience

“…Therefore, there is a mismatch of pitch values between the two protocols (for example, 1.388 in the abdominal spiral scan in Group A vs. 0.813 in Group B). Likewise, although lower tube voltages are generally recommended [4,30], we could choose a minimum of 80 kV in automated tube voltage in Group A but not in Group B, as this would lead to a deactivation of tube current modulation in vHP3, even though this did not result in a statistically significant difference in mean kV. Furthermore, image noise as an image quality reference parameter for ATCM is set lower in vHP3 at 12.5 vs. 40 in vHP.…”

Clinical Advantages of Using Low Tube Voltage in Third-Generation 192-Slice Dual-Source Computed Tomographic Angiography Before Transcatheter Aortic Valve Implantation

“…Also, the CNR was consistently greater than 10 in the images of the aorto-femoral arteries, which exceeds the reported diagnostically acceptable CNR value. 13,24) For patients undergoing TAVI, renal dysfunction is reported as one of prognostic factors in the TAVI perioperative period. 10) Previously, several studies reported the importance of reducing the CM dose and subsequently reducing the risk of CIN.…”

“…11,12) A previous study has reported success using low tube voltage techniques of second-generation dualsource CT (DSCT) system for TAVI planning. 13) But, low tube voltage imaging increased image noise unless tube current output was increased in previous reports. 14,15) Third-generation DSCT systems provide images with reduced noise, owing to substantially higher tube current output at low tube voltage than conventional DSCT systems.…”

Renoprotective Transcatheter Aortic Valve Implantation Without Contrast Media

“…In contrast-enhanced CT, new-generation, dual-source CT and dedicated CT protocols offer sufficient imaging data with low dose of contrast media. [12][13][14] We used a second-generation, dual-source CT scanner ( Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany) with low tube current and 100 kV, which were suggested by the automatic exposure control software CareDose 4D (Siemens Healthcare). Magnetic resonance angiography (MRA) has been reported to be equivalent to contrast-enhanced CT for the calculation of aortic annulus 15,16) but inferior for the assessment of aortic valve calcification and access root.…”