Normal parenchyma is supplied for 80% by the portal vein and only for 20% by the hepatic artery, so the normal parenchyma will enhance maximally in the hepatic phase at 70-80 sec p.i. Cerebral venous thrombosis and multidetector CT angiography: tips and tricks. A 320-row multidetector CT (MDCT) is expected for a good arteryvein separation in terms of temporal resolution. Metastases in the liver are best detected at 70-80 sec p.i., when the liver parenchyma enhances optimally. 6. Stereotactic/ synthes CTA head (COW) Therefore, evaluation was performed within 20.0s after Taa. In some cases it can be difficult to differentiate a pancreatic carcinoma from a focal chronic pancreatitis. In each phase, the mean scores were calculated for the intracranial arteries and veins, and the mean score of the two readers was also calculated for a comprehensive evaluation. A previous study preferred a fixed delay time for bolus tracking owing to the lack of consistency in optimal triggering.23 In another study of brain CTA at 320-row MDCT, a test bolus was also used for a similar reason.22 However, the combination of our proposed scan timing and detection of the CM arrival at the ICA, confirming the ascent of the ICA attenuation from the baseline, could resolve this defect in 3D-CTA with bolus tracking. Acta Radiol October 8, 2013, by Lawrence C. Chow et al The quantitative data acquired was conducted by the normality test method, and was approximately normally distributed (P>0.05), thus the t-test was used. The difference in CT attenuation between the ICA and the SSS (Datt) was calculated for each acquisition: Datt=CT attenuation at the ICACT attenuation at the SSS. AJR 2012; 199:852-860, Appendicitis - Pitfalls in US and CT diagnosis, Acute Abdomen in Gynaecology - Ultrasound, Transvaginal Ultrasound for Non-Gynaecological Conditions, Bi-RADS for Mammography and Ultrasound 2013, Coronary Artery Disease-Reporting and Data System 2.0, Contrast-enhanced MRA of peripheral vessels, Vascular Anomalies of Aorta, Pulmonary and Systemic vessels, Esophagus I: anatomy, rings, inflammation, Esophagus II: Strictures, Acute syndromes, Neoplasms and Vascular impressions, TI-RADS - Thyroid Imaging Reporting and Data System, How to Differentiate Carotid Obstructions, Pulmonary CT Angiography Protocol Adapted to the Hemodynamic Effects of Pregnancy, CT angiography for pulmonary embolism detection: the effect of breathing on pulmonary artery enhancement using a 64-row detector system, Split-Bolus MDCT Urography with Synchronous Nephrographic and Excretory Phase Enhancement. 2006;26 Suppl 1 (suppl_1): S19-41. Of course, through our study, we found that image acquisition with 5-min delay after contrast agent injection was superior in displaying intracranial tuberculosis. The contrast injection and bolus tracking are started at the same time, the scanner counts down 10 seconds and then begins taking bolus tracking images. In fact, not all intracranial lesions had rapid arterial blood supply (e.g., intracranial tuberculosis lesions). The Datt continues in equilibrium until after 8.0s, a period of 2.0s, from Taa (Figure 2). Usually only a portion of the bowel is filled with contrast. Face/Sinus. Especially in small bowel obstruction (SBO) you need to answer the most important question: is there strangulation? Leach JL, Fortuna RB, Jones BV et-al. 22 However, the combination of our proposed scan timing and detection of the CM arrival at the ICA, confirming the ascent of . Pozzi-Mucelli F, Bruni S, Doddi M, Calgaro A, Braini M, Cova M. Detection of intracranial aneurysms with 64 channel multidetector row computed tomography: comparison with digital subtraction angiography. In our quantitative and qualitative assessment, the optimal arterial scan timing should be present between 6.0s and 8.0s after Taa. This is a closed loop obstruction with strangulation. Twenty-seven patients with biopsy-proven squamous cell carcinoma of the head and neck underwent dual-phase helical CT examinations using 100 mL of nonionic contrast material. Ahuja GK, Mohan KK, Prasad K, Behari M. Diagnostic criteria for tuberculous meningitis and their validation. E-mail: Received Received on July 24, 2016; Revised Revised on November 17, 2016; Accepted Accepted on December 13, 2016. In the arterial-dominant phase, attenuation of the vein begins to rise after around 6.0s from Taa. This article covers non-contrast and delayed post-contrast imaging. Bone subtraction 3D CT venography for the evaluation of cerebral veins and venous sinuses: imaging techniques, normal variations, and pathologic findings. Polyethylene glycol (PEG) is also used, and Volumen, which is a low density barium suspension. Further studies with higher temporal resolutions are recommended, although this may be difficult owing to concerns regarding radiation exposure. Matsumoto M, Kodama N, Sakuma J, Sato S, Oinuma M, Konno Y, et al. It is safe to . In this table only specific protocols are summarized, since most institutions have their own standard protocols. Low tube voltage and low contrast material volume cerebral CT angiography, https://doi.org/10.1148/radiol.2302021465, https://doi.org/10.1016/j.ejrad.2007.02.018, https://doi.org/10.1053/j.tvir.2007.03.003, https://doi.org/10.1080/02841850802403748, https://doi.org/10.1016/j.crad.2010.12.014, https://doi.org/10.1016/j.neurad.2016.01.147, https://doi.org/10.1148/radiol.2501071809, https://doi.org/10.1148/radiol.2301021008, https://doi.org/10.1097/rct.0b013e318278e996, https://doi.org/10.1007/s10072-011-0785-z, https://doi.org/10.1016/j.crad.2013.10.021, https://doi.org/10.1080/02841850903055629, https://doi.org/10.1148/radiol.2312030543, https://doi.org/10.1007/s00330-014-3184-z. The contrast agent iohexol (350 mg/mL) was injected intravenously with a dose of 1.2 ml/kg (patient body weight) and a speed of 2.5 ml/sec. Bethesda, MD 20894, Web Policies One could argue that scanning at peak enhancement of the ICA and SSS can achieve stronger enhancement; however, Datt is reduced (Figure 2 and Table 1). Central nervous system tuberculosis: pathogenesis and clinical aspects. We assessed the time at which the maximum Datt and Dscore were simultaneously observed. Second, we assessed the scan timing for arteryvein separation using a fixed CM injection duration of 10.0s. Our results showed that appropriate setting of the scan timing allowed observation of the intracranial arteries or veins in their entirety, with minimal superimposition in each phase, when this short CM injection duration was adapted. Indications include the diagnosis of cerebral venous thrombosisand preoperative anatomy particularly for posterior fossa surgery where the sigmoid sinuses may be compressed (e.g. Wasay M, Kheleani BA, Moolani MK, et al. On a non enhanced CT-scan (NECT) liver tumors are not visible, because the inherent contrast between tumor tissue and the surrounding liver parenchyma is too low. These values were significantly higher than those in the other arterial-dominant phases (p<0.001). TIC is a flow artefact, that consists of relatively poor contrast enhancement in the pulmonary arteries, while there is good enhancement in the SVC and also in the aorta, which seems not logic at all. Differentiation of tuberculous meningitis from acute bacterial meningitis using simple clinical and laboratory parameters. This value was significantly higher than those in other venous-dominant phases (p<0.05) (Table 1). Once the time to peak is determined (ex. 2006;187 (6): 1637-43. Simulation of aortic peak enhancement on MDCT using a contrast material flow phantom: feasibility study. The vessels evaluated were as follows: the intracranial arteries (ICA, M1M2 segments in the middle cerebral artery, anterior communicating artery, pericallosal artery, vertebral artery and basilar artery tip) and veins (SSS, sphenoparietal sinus and jugular bulb). Cherian A, Thomas SV. Results We found 526 lesions in 30 patients, including 22 meningeal thickenings, 235 meningeal tuberculomas/tubercles, and 269 parenchymal tuberculomas/tubercles. A graph showing mean timedensity curves (TDCs) up to 20.0s from contrast media arrival time at the internal carotid artery (ICA): the solid line is the TDC for the ICA and dashed line is the TDC for the superior sagittal sinus (SSS). Measurement was performed in the contralateral side without a mass lesion. A hypovascular liver tumor however will enhance poorly in the late arterial phase, because it is hypovascular and the surrounding liver does also enhance poorly in that phase. The ordering Provider or Radiologist does not want it Philips notes: If Performed on Brilliance 16 Slice Scanners, use up to 80mL contrast. Scan a HEAD WO CONTRAST before CTA HEAD & NECK exam unless: Exam is ordered as Stereotactic for Surgery Planning Patient has had a Head WO Contrast within the last 6 hours. CT attenuation in the supraclinoid segment of the ICA, and in the superior sagittal sinus (SSS) at the level of the obelion, was considered representative of the vessels and was measured in each acquisition for all patients. retrosigmoid craniotomies). Computed tomography (CT) perfusion imaging shows which areas of the brain are adequately supplied or perfused with blood and provides detailed information on delivery of blood or blood flow to the brain. However, the techs can manually override and hit start. injection catheter placed in an antecubital vein. In addition, it is difficult to visualize small vessels with 3D volume rendering using the threshold technique if Datt is small. . A 320-row MDCT is thus expected for the arteryvein separation on brain 3D-CTA. The difference between the mean score for the intracranial arteries and the mean score for the veins (Dscore) was calculated for each phase: Dscore=mean score for the intracranial arteriesmean score for the intracranial veins. PEG and Volumen have the advantage that there is better bowel distension. In terms of sulcus vascular section and tubercle identification, the delayed scan has been shown to have prominent advantages (Figure 4). However, since blood vessels are another major tissue affected by intracranial tuberculosis, with presentation of wall thickening and luminal narrowing (stenosis), proper arterial phase maybe useful and should studied in further investigations. Purpose The CTA of the cerebral arteries is performed to demonstrate the full patency of the cerebral arteries via contrast enhancement. With Contrast: Only one CT contrast study should be scheduled within a 48 hour period. First, we analyzed 4D-CTA data scanned with a tube voltage of 80kVp. Sometimes a lesion will be hypovascular compared to the normal tissue and in some cases a lesion will be hypervascular to the surrounding tissue in a certain phase of enhancement. At pre-contrast CT scan (A), the lesions showed isodensity and mild edema was found in the peripheral regions. Dynamic Expiration for Peds breathe out and hold it out. Because this was a prospective study, and our purpose was to determine the optimal scan timing window for displaying intracranial TB, 3 scans were applied, but the mean total radiation of our study did not exceed the prescribed radiation dose.