Conclusions: Low-dose CT pulmonary angiography can be achieved with use of low kVp (80 and 100) and high-pitch protocol with significant reduction in radiation dose while maintaining diagnostic images of PE. Suspected Pulmonary Embolism: A Management Study . CT angiography should not be used to evaluate for pulmonary embolism when other tests indicate that there is a low probability of a person having this condition. The mean effective dose per patient was also lower in group B (4.8 mSv) than in group A (5.6 mSv). Criteria to be used for Chest CTA or a CT is requested for Pulmonary Emboli which cannot be approved based on Interqual or Milliman criteria. Investigators have proposed that standard pulmonary CTA protocols are less … Pulmonary embolism (PE) is a common condition with high mortality and morbidity. 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. 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 increase in blood volume is thought to contribute to hemodilution of contrast material administered to pregnant patients [5]. A pulmonary CTA protocol optimized for pregnancy significantly improved image quality by increasing pulmonary arterial opacification, improving diagnostic adequacy, and decreasing transient interruption of the contrast bolus by unopacified blood from the IVC. Cystic Hepatic Lesions: A Review and an Algorithmic Approach, Review. To estimate vessel noise, the reviewers recorded the attenuation and SD of the MPA and the attenuation of air for each CT study. The mean image percentage noise measurements were lower in group A than in group B (1.52 vs 1.79, respectively; p = 0.04) despite similar CT exposure parameters. In the past decade, CT pulmonary angiography has been increasingly used as the primary diagnostic imaging examination after chest radiography for the evaluation of patients with suspected PE. The aim of this study was to analyze the dose reduction and image quality achieved by using 80 kV instead of 100 kV in CT pulmonary angiography protocols. The role of pulmonary CT angiography and selective pulmonary angiography in endovascular management of pulmonary artery pseudoaneurysms associated with infectious lung diseases. 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. Yilmaz Ö, Üstün ED, Kayan M, et al. This injection was followed by a 50-mL IV saline flush. The increase in cardiac output was also minimized by using a high concentration of contrast medium and by using bolus tracking, both of which are part of standard practice for CTA of pregnant patients in our institution. cm–1) [14]. Several study limitations are acknowledged. CT Angiography of the Upper Extremity Arterial System: Part 1—Anatomy, Technique, and Use in Trauma Patients, Original Research. The remaining 17 patients had normal radiologic findings. The remaining 20 patients had normal radiologic findings. There was a strong positive relationship between mean pulmonary arterial attenuation and good objective image quality (r = 0.67, p = 0.001). 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. 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. ... Ct pulmonary angiogram muhammed Yasar. Fig. To estimate vessel noise, the reviewers recorded the attenuation and SD of the MPA and the attenuation of air for each CT study. 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. 2–4 CTPA is a standard procedure that obtains a CT volume while intravenously injected iodinated contrast media (CM) opacifies the pulmonary arteries. 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. CT angiography for pulmonary embolism detection: the effect of breathing on pulmonary artery enhancement using a 64-row detector system. Conversely, an indeterminate rate of 35.7% was described in a smaller study of 25 patients in which a lower volume of 75 mL of iodinated contrast material and held maximal inspiration were used [7]. The mean effective dose per scan was lower in group B (4.8 mSv) than in group A (5.3 mSv) (p = 0.09). [Dual-source CT scanners provide high-pitch dual source protocols … Split-Bolus MDCT Urography with Synchronous Nephrographic and Excretory Phase Enhancement, Review. The first 28 CTA studies were performed of 25 pregnant patients using a standard pulmonary CTA imaging protocol (Table 1) similar to that used on nonpregnant patients (group A). KIVC calculations were based on the assumption that the SVC and IVC were the sole contributors of flow to the right heart. Vessel opacification was provided by IV injection of 95 mL of iopamidol (Niopam 370) via the antecubital vein. Criteria to be used for Chest CTA or a CT is requested for Pulmonary Emboli which cannot be approved based on Interqual or Milliman criteria. Second, triple rule-out CT protocol is associated with significantly higher radiation dose when compared to the CTPA protocol, but with low diagnostic yield of less than 10%. 2007 Jul. This effect, known as the “thoracoabdominal pump,” is likely to be prominent in pregnancy because of inherently raised IVC pressures. A Combination of Normal-Dose Corticomedullary Phase With Low-Dose Unenhanced and Excretory Phases, Review. 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. In all cases, the clinical and study reinterpretations agreed. The mean effective dose per patient was also lower in group B (4.8 mSv) than in group A (5.6 mSv). The aim of this quality assurance exercise was to investigate if a change in CT pulmonary angiography (CTPA) scanning protocol resulted in improved opacification of the pulmonary arteries. 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). Diagnostic quality of CT pulmonary angiography in pulmonary thromboembolism: A comparison of three different kV values. A total of 102 CTPAs performed by 20 ml (ultra-low volume: ULV) and 74 CTPAs performed by 40 ml (low volume: LV) protocol … These data indicate a 143-HU difference in mean opacification between the two groups. NB: This article is intended to outline some general principles of protocol design. [1, 2] In 1922, Wharton and Pierson reported the first radiographic description of PE. 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. Although this protocol optimized for imaging pregnant patients significantly improved pulmonary CTA image quality, two of the 20 patients in group B had nondiagnostic studies. Hounsfield unit values of acute and chronic pulmonary emboli. 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. 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. Evaluation of subjective image quality involved categorizing a study as either adequate or inadequate on the basis of one’s ability to diagnose PE, the adequacy of pulmonary arterial opacification, and the presence or absence of significant motion artifact and image noise. 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]. The causative mechanism of poor pulmonary arterial opacification during pulmonary CTA in pregnancy is multifactorial. Computed tomographic (CT) pulmonary angiography has been evaluated with meta-analysis and has demonstrated sensitivities of 53%–100% and specificities of 83%–100% (, 6), wide ranges that are explained in part by technologic improvements over time. Three patients did not undergo further imaging and PE was excluded clinically. 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. 2). This difference achieved statistical significance (p = 0.03) because three patients in group A had repeat CTA studies. Acta Radiol October 8, 2013 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. NB: This article is intended to outline some general principles of protocol design. 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. 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. Optimizing Protocols for the Individual Patient in CT Pulmonary Angiography. • Wittram C, Maher MM, Halpern E, Shepard JO. angiography (CTA) has evolved into a routine minimally-invasive vas and cardiac CT have evolved into widely available routine clinical applications The quality of a CT angiogram or a cardiac CT strudy depends to a great extent on the appropriate selection of CT data acquisition and contrast medium injection parameters. Readers were not blinded to the CTA protocol used. Several study limitations are acknowledged. 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. 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). The contrast agent is injected into a vein (not an artery as in conventional angiography), usually in the arm. [3] Images depicting clots in the pulmonary arterial system are provided below. cm–1) [14]. 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. In group A, eight patients had nondiagnostic pulmonary CTA studies. The purpose of this study was to investigate the clinical application of computed tomography pulmonary angiography (CTPA) in patients with suspected pulmonary embolism (PE) based on a ... patient records, the positive rate of PE was 30.7%. 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. exercise was to investigate if a change in CT pulmonary angiography (CTPA) scanning protocol resulted in improved opacification of the pulmonary arteries. Three patients underwent repeat pulmonary CTA. 1,2 Since the 1990s, CT pulmonary angiography (CTPA) has become the method of choice for imaging in suspected PE. The subsequent 20 pregnant patients referred for pulmonary CTA were imaged using a CTA protocol adapted to minimize the hemodynamic effects of pregnancy (Table 1). A thoracoabdominal gradient exists between the IVC and the right heart. Comparison was made between the smart prep protocol (SPP) and the test bolus protocol (TBP) for opacification in the pulmonary trunk. pmid:17940308 . Bilateral central pulmonary embolism was detected (white arrows). What is a CT pulmonary angiogram? In group B, final diagnoses included pneumonia (n = 1) and atelectasis (n = 2). Total blood volume increases by 50% during early pregnancy. 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. 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. 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. Our study was limited by its retrospective nature and small number of patients. The inadequate group comprised CTA studies with poor pulmonary arterial enhancement, substantial noise, or substantial motion artifact. Patient age, week of gestation, vascular opacification in Hounsfield units, KIVC, effective dose, and image noise are expressed as mean values ± SD. Of the CTA studies with the artifact, the average relative IVC contributions (KIVC) to the RA and RV were 84.4% and 84.7%, respectively, whereas the average KIVC values for those CTA studies without the artifact were 46.9% and 52.7% (p < 0.0001), respectively. Protocol … 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]. Protocol … One of these patients had a diagnostic study that excluded PE, and the other two patients had nondiagnostic repeat studies. Jones SE, Wittram C. The indeterminate CT pulmonary angiogram: imaging characteristics and patient clinical outcome. Lung volume was quantified employing semi-automated lung software that calculated lung volumes (intellispace -Philips). The second patient had a nondiagnostic study, but right upper lobe consolidation was shown and a concomitant PE was thought to be unlikely on clinical grounds; no further imaging was performed. 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]. Pulmonary arterial opacification was significantly higher in all locations in group B than group A and is detailed in Table 2. 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]. 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. 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. In group B, two patients had nondiagnostic studies. In group A, final diagnoses included pneumonia (n = 2), pleural effusion (n = 1), pneumothorax (n = 1), and PE (n = 1). cerebral angiography – to check the blood vessels in and around the brain ; pulmonary angiography – to check the blood vessels supplying the lungs ; renal angiography – to check the blood vessels supplying the kidneys ; Occasionally, angiography may be done using scans instead of X-rays. 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. CT pulmonary angiogram (CTPA) is a medical diagnostic test that employs computed tomography (CT) angiography to obtain an image of the pulmonary arteries.Its main use is to diagnose pulmonary embolism (PE). 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. Arteries are blood vessels that carry blood away from the heart. CT Angiography of the Upper Extremity Arterial System: Part 1—Anatomy, Technique, and Use in Trauma Patients, Original Research. The adequate group included CTA studies with good pulmonary arterial enhancement and without significant noise or motion artifact. 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