MDCT for suspected pulmonary embolism: multi-institutional survey of 16-MDCT data acquisition protocols

Abstract

The purpose of this study was to determine the extent to which a consensus exists on multidetector row computed tomography (MDCT) protocol parameters for suspected pulmonary embolism (PE). In August of 2004, a questionnaire addressing a number of body MDCT protocols was mailed to 99 fellows of the Society of Computed Body Tomography, representing a total of 46 institutions. In May 2005, this was followed up with a second mailing. The survey requested details pertaining to protocols for the most advanced MDCT scanner in the department. The overall survey response rate of 37% (17/46) yielded 15 protocols for 16-MDCT imaging of suspected PE. This data was tabulated and revealed a consensus for the use of bolus tracking, rapid contrast infusion, caudo-cranial scanning, the narrowest detector row collimation, and thin (<2 mm) reconstruction sections. However, contrast infusion timing, contrast concentration, and implementation of radiation dose modulation were variable. This compilation of protocols reflects recently published studies advocating the use of narrow acquisition collimation and reconstruction sections for MDCT of suspected PE. Future studies are necessary to elucidate the optimal intravenous contrast infusion parameters and further assess the efficacy of reduced radiation dose protocols.

Iterative reconstruction of pulmonary MDCT angiography: Effects on image quality, effective dose and estimated organ dose to the breast

“…The average effective dose in our unselected population of females (with BMI widely ranging from 15 to 48) was 2.73 mSv in th e FBP group, i.e. at the lower end of the dose ranges demonstrated in the multi-institutional studies 5,6,9 . Thus, it can be inferred that our local protocols were optimized in accordance with ALARA principles.…”

“…Nonetheless, even recent publications have indicated that there is a substantial variance in doses applied for the same types of CT procedures at different institutions, as well as there being significant potential for reducing radiation dose in routine CT examinations 5,6 . A multi-centric study from California estimates that one in 330 females undergoing MDCTA for ruling out pulmonary embolism at the age of twenty will develop a radiation induced cancer 5 .…”

“…Notably, a multi-institutional survey among fifteen different pulmonary MDCTA protocols 6 showed considerable variations in the peak kilovoltage and miliampere-seconds used: eleven sites routinely used 120 kV and four sites 140 kV protocols, even in low BMI subjects; no breast dose measurements were provided. Also, in a study by Parker et al 15 tube voltage was set to 140 kV in all subjects, leading to a high mean breast dose of 20 mGy.…”

Ultralow contrast medium doses at CT to diagnose pulmonary embolism in patients with moderate to severe renal impairment: a feasibility study

“…Decreasing x-ray tube peak kilovoltage (kVp) from commonly used 120 and 140 kVp [5] to 80-90 kVp brings the x-ray spectra closer to the k-edge of the iodine and increases the iodine attenuation of photons [6][7][8]. This would permit a reduction of the CM dose while keeping vascular enhancement at the same level as that obtained at 120 and 140 kVp.…”

“…In a survey of 16-channel multidetector CT (16-MDCT) protocols for PE, CM doses ranged from 28 to 55 g of iodine (I) [5]. Decreasing x-ray tube peak kilovoltage (kVp) from commonly used 120 and 140 kVp [5] to 80-90 kVp brings the x-ray spectra closer to the k-edge of the iodine and increases the iodine attenuation of photons [6][7][8].…”