Comparison was made between the smart prep protocol (SPP) and the test bolus protocol (TBP) for opacification in the pulmonary trunk. [3] Images depicting clots in the pulmonary arterial system are provided below. 1,2 Since the 1990s, CT pulmonary angiography (CTPA) has become the method of choice for imaging in suspected PE. When pulmonary CTA is performed of pregnant patients using a deep held inspiration, the relative contribution of the IVC to the right heart can increase and can lead to interruption of the contrast bolus entering the right heart from the SVC [7]. Pulmonary angiography is an invasive procedure and due to its costs and potential risks is usually reserved for patients in whom more information or certainty of the diagnosis of PE are necessary. To propose a protocol for pulmonary angiography using 64-slice multidetector computed tomography (64-MDCT) with 50 mL of iodinated contrast material, in an unselected patient population, as well as to evaluate vascular enhancement and image quality. Group A consisted of 25 patients who underwent 28 pulmonary CTA studies; three patients underwent repeat CTA because the initial study was nondiagnostic. TABLE 2: Opacification of the Pulmonary Arteries on CT Angiography. IVC pressure is particularly high when the pregnant patient is in the supine position, where a sixfold increase in pressure has been observed in the third trimester [22]. The mean effective dose per scan was lower in group B (4.8 mSv) than in group A (5.3 mSv) (p = 0.09). As a result, these patients had a higher cumulative dose than those in group B; none of the group B patients underwent repeat CTA studies. In these equations, the relative IVC contributions to the RA and RV were calculated by equating attenuation (C) in Hounsfield units in these chambers to a weighted average of the attenuations of the SVC and IVC assuming that the SVC and IVC are the sole contributors of flow to the right heart. Patient age, week of gestation, vascular opacification in Hounsfield units, KIVC, effective dose, and image noise are expressed as mean values ± SD. One study that showed transient interruption of the contrast bolus in group B was considered diagnostic at the time of image acquisition and met both subjective and objective criteria of “good” and “adequate” at study reinterpretation. Inventive protocols of CT pulmonary angiography (CTPA) avoid artifacts in right pulmonary artery (rPA), improving detectability of pulmonary embolism (PE) Miho Ikura, Hirohiko Ikura, Hisayuki Abe, Seiichiroh Watanabe, Shin Kimoto, Yohko Kawawa. CT pulmonary angiography protocol: Multidetector CT is preferred (at least 16 slices) Caudal-cranial direction: Most emboli are located in the lower lobes and, if the patient breathes during image acquisition, there is more excursion of the lower lobes compared with the upper lobes. allergy) and time constraints. CTA of the pulmonary arteries was performed on 200 patients with suspected pulmonary … This effect, known as the “thoracoabdominal pump,” is likely to be prominent in pregnancy because of inherently raised IVC pressures. The mean effective dose per patient was also lower in group B (4.8 mSv) than in group A (5.6 mSv). Pulmonary CT Angiography Protocol Adapted to the Hemodynamic Effects of Pregnancy, Transient Interruption of Contrast Material by Unopacified Blood From the Inferior Vena Cava, Original Research. The flow rate was kept constant at 6 mL/s throughout the procedure, and contrast administration was followed by a 50-mL IV saline flush. Role of CT Pulmonary Angiography. to Reduce the use of CT Pulmonary Angiography in . Pulmonary arterial opacification was significantly higher in all locations in group B than group A and is detailed in Table 2. To compare intravenous contrast material (CM) injection protocols for dual-energy CT pulmonary angiography (CTPA) in patients with suspected acute pulmonary embolism with regard to image quality and pulmonary perfused blood volume (PBV) values. Calculations were performed on a standard PC using a statistical analysis program (Minitab, version 15, Minitab). Three patients did not undergo further imaging and PE was excluded clinically. Recent studies of CT pulmonary angiography in children (13,14) have reported a wide range of radiation doses (2–26 mSv), which is most likely due to the use of various types of multidetector CT scanners and differing CT pulmonary angiography protocols at different institutions. The objective evaluation classified mean pulmonary arterial opacification as good (≥ 210 HU), acceptable (170–209 HU), or poor (≤ 169 HU), as described in a recent study [15]. In the CTA studies with the artifact, the mean attenuations (± SD) of the proximal high-attenuation region, intervening low-attenuation region, and distal high-attenuation region were 264 ± 64 HU, 134 ± 50 HU, and 229 ± 75 HU, respectively (Fig. Yilmaz Ö, Üstün ED, Kayan M, et al. Statistical methods included the Shapiro-Wilk test to confirm normal distribution, Student t test, chi-square test, and Pearson correlation coefficient. In group B, the hemodilutional effects of pregnancy were minimized by using a higher volume of contrast material injected at a higher rate than used in group A. Jones SE, Wittram C. The indeterminate CT pulmonary angiogram: imaging characteristics and patient clinical outcome. In group B, the hemodilutional effects of pregnancy were minimized by using a higher volume of contrast material injected at a higher rate than used in group A. It is also a limitation of the study that readings were made by consensus and not independently; a consensus review was thought to be appropriate given the relative infrequency of respiratory artifacts on CTA in the general population. Significance values were set at p ≤ 0.05. Images were reconstructed with a slice thickness of 1 mm and reviewed using mediastinal window settings (center, 50 HU; width, 350 HU). NB: This article is intended to outline some general principles of protocol design. We thank the CT radiographers at St. Vincent’s University Hospital—in particular, Susan Collins and Sheena O’Keeffe—and chief physicist Michael Casey for their important contributions to image acquisition and dose calculation in this study. (OptIPeCT) The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. CTA of the pulmonary arteries was performed on 200 patients with suspected pulmonary embolism (PE). These are called CT angiography or MRI angiography. The mean pulmonary attenuation was also higher in group B than in group A: 321 ± 148 HU compared with 178 ± 67 HU (p = 0.0001). When the threshold of attenuation in the MPA was reached, the patient was instructed to perform shallow held inspiration, after adequate coaching by a technologist encouraging a shallow breath and the avoidance of a Valsalva maneuver. Other larger studies do not describe the breathing instructions used [6, 15] and report indeterminate rates of 17% and 5.6% using 100–125 mL and 80–95 mL of contrast material, respectively. A Combination of Normal-Dose Corticomedullary Phase With Low-Dose Unenhanced and Excretory Phases, Review. adequate enhancement of … J Vasc Interv Radiol . The current standard of care for members with suspected pulmonary embolism is a spiral CT scan, also called a CTA, CT PA (computed tomography pulmonary angiography), MDCT (multidector CT) or helical CT scan. CT Angiography of the Upper Extremity Arterial System: Part 1—Anatomy, Technique, and Use in Trauma Patients, Original Research. Lung volume was quantified employing semi-automated lung software that calculated lung volumes (intellispace -Philips). It is a preferred choice of imaging in the diagnosis of PE due to its minimally invasive nature for the patient, whose only requirement for the scan is an intravenous line. The adequate group included CTA studies with good pulmonary arterial enhancement and without significant noise or motion artifact. This increase in blood volume is thought to contribute to hemodilution of contrast material administered to pregnant patients [5]. These data indicate a 143-HU difference in mean opacification between the two groups. Objective. Lung scintigraphy is not susceptible to the hemodynamic effects of pregnancy and remains a reliable tool for excluding PE in patients with normal findings on chest radiography while additionally conferring a lower maternal radiation dose than pulmonary CTA [12, 13]. Transient interruption of the contrast bolus by unopacified blood from the IVC was a causative factor in one case and the second nondiagnostic study was caused by poor peak arterial enhancement. Pulmonary arterial opacification was significantly higher in all locations in group B than group A and is detailed in Table 2. Echocardiographic data excluding a right-to-left shunt were not available in our patient group, although none of the subjects had a documented history of cardiac disease in their electronic records. We thank the CT radiographers at St. Vincent’s University Hospital—in particular, Susan Collins and Sheena O’Keeffe—and chief physicist Michael Casey for their important contributions to image acquisition and dose calculation in this study. One of these patients had a diagnostic study that excluded PE, and the other two patients had nondiagnostic repeat studies. We instituted a new, simple CT pulmonary angiography (CTPA) contrast material timing protocol using a standard empiric delay to replace our previous timing bolus method. These measurements were then combined to calculate mean pulmonary opacification. Investigators have proposed that standard pulmonary CTA protocols are less … Patient age, week of gestation, vascular opacification in Hounsfield units, KIVC, effective dose, and image noise are expressed as mean values ± SD. The patient was examined with the 70-kVp dual-source CT pulmonary angiography protocol (Group A). KIVC values range from 0 to 1.0; a high KIVC (> 0.8) indicates a larger contribution from the IVC to the right heart relative to the SVC and suggests the presence of transient interruption of the contrast bolus by unopacified blood from the IVC, whereas healthy control subjects have average KIVC values of approximately 0.5 [17]. The remaining 20 patients had normal radiologic findings. Computed Tomography Pulmonary Angiography during Pregnancy: Radiation Dose of Commonly Used Protocols ... scan and Injection Protocol The three CT scanners investigated in this study were a The causative mechanism of poor pulmonary arterial opacification during pulmonary CTA in pregnancy is multifactorial. The pulmonary vasculature may be evaluated with various invasive and noninvasive methods. Significance values were set at p ≤ 0.05. 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