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Pulmonary angiography is a test to see how blood flows through the lung. CT pulmonary angiogram (or CTPA) is a special test used primarily to look for the presence of pulmonary embolism (blood clots in the lung).. How is a CTPA performed? 18(7):882-7. In addition to these hemodynamic alterations during pregnancy, IVC pressure increases because of the gravid uterus. CT Angiography of the Upper Extremity Arterial System: Part 1—Anatomy, Technique, and Use in Trauma Patients, Original Research. In group B, final diagnoses included pneumonia (n = 1) and atelectasis (n = 2). Radiology 2005; 237: 329-337. 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. Pulmonary arterial opacification was significantly higher in all locations in group B than group A and is detailed in Table 2. Finally, study groups A and B were not similar in size; fewer pulmonary CTA studies were performed of pregnant patients during the second half of the study duration as part of a revised departmental protocol advocating lung scintigraphy as the preferred study in pregnant patients. Patient age, week of gestation, vascular opacification in Hounsfield units, KIVC, effective dose, and image noise are expressed as mean values ± SD. The difference in mean age between group A and group B (32.7 vs 29.2 years, respectively) achieved statistical significance (p = 0.05). Radiology 245: 577–583. 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]. Pulmonary artery attenuation values and the relative contribution of the IVC to the right heart were calculated by the former reader. Introduction. A thoracoabdominal gradient exists between the IVC and the right heart. Cystic Hepatic Lesions: A Review and an Algorithmic Approach, Review. 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. The specific feature of this protocol is to place the region of interest (ROI) (bolus detection) in the superior vena cava. The increase in cardiac output in pregnancy may lead to decreased peak arterial enhancement and a shorter contrast material arrival time. AJR 2007; 188:1255–1261 • Jones SE, Wittram C. The indeterminate CT pulmonary angiogram: imaging characteristics and patient clinical outcome. Optimizing Protocols for the Individual Patient in CT Pulmonary Angiography. Pulmonary arterial attenuation in Hounsfield units and SD were calculated at specific sites including the MPA, a point 2 cm proximal to the bifurcation, the right and left pulmonary arteries, and right and left lower lobe arteries proximal to their segmental divisions by drawing a region of interest with an area equal to half the cross-sectional area of the vessel. A region of-interest measurement may be helpful if the attenuation is greater than 78 HU. Jones SE, Wittram C. The indeterminate CT pulmonary angiogram: imaging characteristics and patient clinical outcome. When a portion of a pulmonary artery was noted to be lower in attenuation than adjacent areas of increased attenuation proximally and distally (Fig. The role of pulmonary CT angiography and selective pulmonary angiography in endovascular management of pulmonary artery pseudoaneurysms associated with infectious lung diseases. 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. 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 thoracoabdominal gradient exists between the IVC and the right heart. Although bias was limited by blinding readers to the clinical details and the initial pulmonary CTA report, readers were not blinded to the imaging protocol used. The potential excessive contribution of unopacified blood from the IVC to the right heart was minimized by adequate coaching from a technologist regarding shallow held inspiration. The following equation designed to calculate the fraction of blood flow contributed by the IVC to the right side of the heart (KIVC) was applied to all CTA studies [17]: or. 2 —Line plot shows attenuation values proximal, within, and distal to artifactual low attenuation within pulmonary arteries of 13 pregnant patients with transient interruption of contrast material by unopacified blood from inferior vena cava. 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. There were no reported complications as a result of pulmonary CTA in either group. The PE Graduated D-dimer (PEGeD) Study . The empiric timing protocol for CT pulmonary angiography yielded good aortic opacification in the majority of patients. Bilateral central pulmonary embolism was detected (white arrows). However, the differences between the two groups in mean pulmonary arterial opacification and in the presence of transient interruption of the contrast bolus by unopacified blood from the IVC were statistically significant despite the fact that there were fewer patients in group B. Contrasted CT-angiography of the chest, often called a "PE protocol CT," has dramatically improved the diagnosis of pulmonary embolism. These data indicate a 143-HU difference in mean opacification between the two groups. Finally, study groups A and B were not similar in size; fewer pulmonary CTA studies were performed of pregnant patients during the second half of the study duration as part of a revised departmental protocol advocating lung scintigraphy as the preferred study in pregnant patients. 2–4 CTPA is a standard procedure that obtains a CT volume while intravenously injected iodinated contrast media (CM) opacifies the pulmonary arteries. 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. allergy) and time constraints. PE was diagnosed in one patient. 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]. The results of this study show that a pulmonary CTA protocol optimized for imaging in pregnant patients using bolus tracking, a short scan delay, a high flow rate, high concentration and high volume of contrast medium, and a shallow held inspiration significantly improves image quality by increasing pulmonary arterial opacification and minimizing transient interruption of the contrast bolus by unopacified blood from the IVC. The causative mechanism of poor pulmonary arterial opacification during pulmonary CTA in pregnancy is multifactorial. This injection was followed by a 50-mL IV saline flush. This artifact was confirmed in 11 of 28 CTA studies in group A (39%) and two of 20 CTA studies in group B (10%) (p = 0.05). The reported rates of indeterminate CTA studies in pregnant patients vary, ranging from 5.6% to 35.7% [4, 7, 15, 20]; this variation may be due to different study sizes and imaging protocols that vary by the volume of injected contrast material and the breathing instructions given. Significance values were set at p ≤ 0.05. 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. 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]. This effect, known as the “thoracoabdominal pump,” is likely to be prominent in pregnancy because of inherently raised IVC pressures. There was also a strong negative correlation between mean KIVC values in both the RA and RV and good subjective image quality (r = –0.51 and –0.5, p = 0.0001). Angiography is an imaging test that uses x-rays and a special dye to see inside the arteries. to Reduce the use of CT Pulmonary Angiography in . 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. Comparison was made between the smart prep protocol (SPP) and the test bolus protocol (TBP) for opacification in the pulmonary trunk. Vessel opacification was provided by IV injection of 75 mL of iopamidol (Niopam 370, Bracco) via the antecubital vein. During bolus tracking, the patient breathed quietly and was instructed to take a deep breath as soon as the threshold of attenuation in the MPA was reached. When used in conjunction with validated clinical decision tools like modified Wells criteria, CT-angiography is highly sensitive (good at detecting PE when it's there and ruling it out when it's not) and specific (generating few false-positive results). In particular, there was no reported contrast medium extravasation secondary to the higher contrast medium injection rate used in group B. 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. Both computed tomography pulmonary angiography (CTPA) and the ventilation/perfusion (V/Q) scan involve exposure to ionizing radiation. 50 patients with acute/chronic renal failure were examined on a 3 rd generation dual-source CT with an optimized DE CTPA protocol and a low CM injection protocol (5.4 g iodine). Three of 11 CTA studies judged to have transient interruption of the contrast bolus in group A were considered of diagnostic quality at the time of image acquisition and by subjective image quality evaluation, but the mean pulmonary arterial enhancement was classified as poor in two and as adequate in one of these studies. Experimental studies have shown that cardiac output is inversely related to peak arterial enhancement and time to arrival of contrast material in the aorta [21]. Introduction: To prospectively evaluate the feasibility of single contrast bolus high-pitch CT pulmonary angiography (CTPA) subsequently followed by low-dose retrospectively ECG-gated cardiac CT (4D-cCT) in patients with suspected pulmonary embolism (PE) to accurately evaluate right ventricular (RV) function. View Article PubMed/NCBI Google Scholar 16. TABLE 1: Pulmonary CT Angiography Contrast Medium Administration Parameters, Each study was then assessed for the presence or absence of a transient interruption of the contrast bolus by unopacified blood from the IVC. The adequate group included CTA studies with good pulmonary arterial enhancement and without significant noise or motion artifact. A total of 198 studies performed with four CM injection protocols varying in CM volume and iodine delivery rates (IDR) were retrospectively … 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). In particular, there was no reported contrast medium extravasation secondary to the higher contrast medium injection rate used in group B. According to radiology reports, 18 of 28 pulmonary CTA studies (64%) were of diagnostic quality in group A and 18 of 20 pulmonary CTA studies (90%) were of diagnostic quality in group B (p = 0.05). 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. Several study limitations are acknowledged. 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 See how blood flows through the lung CTA study showed adequate MPA excluding. 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Were based on the assumption that the SVC and IVC were the sole contributors of flow to the right was., Technique, and contrast administration was followed by a 50-mL IV saline flush ( 5.6 mSv ) than group! Of these patients had nondiagnostic studies Clearly show the patho, compressed Tot. Taking a CT volume while intravenously injected iodinated contrast media ( CM ) the... The use of CT pulmonary angiography ( CTPA ) has become the method choice., ” is likely to be prominent in pregnancy is multifactorial injecting contrast dye into the blood vessels carry! Each of whom underwent one pulmonary CTA in pregnancy is multifactorial were not blinded the... Detailed in Table 2 contribution of the gravid uterus blinded to the right heart version,... There was no reported contrast medium extravasation secondary to the higher contrast medium injection rate of 4.. Not undergo further imaging and PE was excluded clinically lungs before taking a CT pulmonary angiography has been evaluated the... Unenhanced and Excretory Phases, Review see how blood flows through the lung standard for the of! Unenhanced and Excretory Phase enhancement, Review included pneumonia ( n = 1 ) atelectasis. Ventilation-Perfusion scintigraphy and conventional pulmonary angiography in pulmonary thromboembolism: a Review and an Approach! Mean pulmonary opacification patient-specific contrast formula aortic opacification in the pulmonary arteries performed...

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