Dual-phase CT Angiography Research Articles

Rapid identification and prognosis evaluation by dual-phase computed tomography angiography for stroke patients with a large ischemic region in the anterior circulation treated with endovascular thrombectomy.

To investigate the value of dual-phase head-and-neck computed tomography angiography (CTA) in assessing advantages and risks associated with mechanical thrombectomy for stroke with a large ischemic region in the anterior circulation within 6 h of onset. We retrospectively analyzed the data of patients with acute occlusion of the internal carotid artery or middle cerebral artery-M1 segment. Baseline dual-phase CTA was performed for collateral grading using the 4-point visual collateral score (0, 0% filling; 1, >0% and ≤50% filling; 2, >50 and <100% filling; 3, 100% filling). The rates of modified Rankin score (MRS) ≤ 3 at 90 days, any intracranial hemorrhage (ICH) within 48 h, malignant cerebral edema within 24 h, and all-cause 90-day mortality were analyzed. Among the 69 study patients, 15, 26, 17, and 11 patients had collateral grades of 0, 1, 2, and 3, respectively. At 90 days, the MRS was ≤3 in 0, 8.33, 29.41, and 36.36% of patients with grades 0, 1, 2, and 3, respectively. ICH incidence was 73.33, 57.69, 29.41, and 18.18% for grades 0, 1, 2, and 3, respectively, while the incidence of malignant brain edema was 100, 76.92, 35.29, and 0%, respectively. All-cause 90-day mortality was 53.33% for grade 0 and 30.77% for grade 1; no deaths occurred at grades 2 and 3. Collateral grading based on dual-phase CTA enables simple and rapid preoperative evaluation prior to mechanical thrombectomy for acute anterior-circulation stroke with a large ischemic focus, particularly for patients presenting within the 6-h time window.

Breakthrough of dual-phase CT angiography features of carotid web and its correlation with ischemic stroke

PurposeTo investigate the diagnostic value of dual phase CT angiography (CTA) in carotid web and its correlation with ischemic stroke. MethodsThe imaging data of 726 patients with cervical CTA from January 2015 to November 2019 in Taizhou People's hospital were retrospectively and consecutively analyzed. A total of 16 patients with 23 carotid webs were obtained. The location, morphology and clinical data of 16 patients were observed. Carotid web was identified by two experienced radioimaging experts according to the characteristics of a thin intraluminal filling defect along the posterior wall of the carotid bulb on sagittal CTA and a septum structure in arteries on axial CTA. ResultsIn the arterial phase, 23 carotid webs in 16 patients showed membrane like separation in the lumen of the posterior wall of the carotid bulb, and one web extended into the internal and external carotid arteries in a "Y" shape. There were 9 males and 7 females. In venous phase, 16 carotid webs showed linear enhancement, and 15 sites showed delayed emptying of contrast medium at the lateral margin. Five patients were acute or chronic ischemic stroke. The kappa coefficient for interobserver agreement in diagnosing carotid web was 0.79. ConclusionDual-phase CTA is effective and reliable method to identifying carotid webs, which may be associated with ischemic stroke.

Association of Dual-Phase Computed Tomography Angiography and CT-Perfusion in Patients with Acute Ischemic Stroke Beyond the 6-Hour Window

Background: There is controversy regarding the need to use advanced imaging to select candidates for thrombectomy in late window acute ischemic stroke (AIS). Hypoattenuation on CT angiography source images (CTA-SI) in arterial phase has been shown to be more sensitive than Alberta Stroke Program Early CT score (ASPECTS) of brain parenchyma to determine tissue at risk of ischemia. Our hypothesis is that the addition of a second acquisition at 35-50 seconds could complement the assessment of hypoperfused tissue that fails to receive flow through pial vessels. Methods: Patients with large vessel occlusion and 6-16 hours from symptom onset, admitted between August 2019 and July 2022 were evaluated with dual-phase CT angiography (CTA) and CT-perfusion. The association between automated CT-perfusion values and dual-phase CTA was assessed through a correlation coefficient. Results: Pearson's coefficient demonstrated a high correlation between ischemic core volume and delayed CTA-SI with an inverse association of -0.91 and between Tmax≥6 sec volume and arterial CTA-SI with a value of -0.83. Conclusion: CTA-derived source images (CTA-SI) in two phases may be useful in the selection of patients with AIS presenting beyond the 6-hour window.

Unilateral external jugular vein aneurysm in a dog

An 11-month-old Staffordshire Bull Terrier was referred with a two-month history of fluctuating unilateral jugular groove swelling, which appeared to enlarge after exercise. There was no history of trauma. Multimodal imaging findings (using transdermal and transesophageal ultrasound and dual phase computed tomography angiography) were consistent with large, saccular, left jugular vein aneurysm, running parallel to the left carotid artery. There did not appear to be any arteriovenous communication present. There were no cardiac abnormalities found on echocardiography. Following surgical excision, histopathological analysis supported the clinical suspicion of a congenital external jugular venous aneurysm.

A common celiacomesenteric trunk is a rare anatomic variant in dogs.

With the increasing use of CT and MRI for diagnostic imaging and planning of interventional procedures, it is important for veterinary radiologists to be familiar with variations in normal vascular anatomy and not mistake them for pathology. The arterial blood supply to the cranial abdominal viscera is provided by the celiac and the cranial mesenteric arteries. A common celiacomesenteric trunk (CMT) has been reported as a rare anatomical variant in dogs. The goals of this retrospective, observational, cross-sectional prevalence study were to determine the prevalence of a CMT in dogs with non-abdominal disease and compare it to the prevalence in dogs with portosystemic shunts (PSS). Magnetic resonance imaging studies of the thoracolumbar and lumbosacral spine in dogs that included the origin of the celiac and cranial mesenteric arteries and dual-phase CT angiography studies of the abdomen in dogs with portosystemic shunts were retrospectively reviewed by a veterinary student and a board-certified veterinary radiologist. The prevalence of a CMT was determined as the proportion of dogs diagnosed with this vascular anomaly in the MRI and CT group, respectively. Fisher's exact test was used to determine any association of a CMT with the concurrent presence of a PSS, sex, and breed size. A CMT was identified in seven of 606 (1.2%) MRI studies and in none of 47 abdominal CT studies. There was no association between the presence of a CMT and PSS (P=1.000), sex (P=.4694), or breed size (P=1.000). A CMT is a rare incidental finding in dogs.

Targeting Peritumoral Lesions Identified by Computed Tomography and Magnetic Resonance Imaging in Feline Injection-Site Sarcomas for Microscopic Examination

Peritumoral lesions identified during in vivo imaging of feline injection-site sarcoma (FISS) are frequently interpreted as neoplastic. We recently showed that most peritumoral imaging-identified lesions (PTIILs) in FISS are non-neoplastic. In this article, we describe a protocol to target PTIIL for microscopic examination and report on the protocol's performance. Ten client-owned cats with FISS were prospectively enrolled. A fiducial marker sutured onto the skin, centered on the palpable mass, served as reference point throughout the study. Each FISS and surrounding tissue was imaged in vivo by dual phase computed tomography angiography and multiple magnetic resonance imaging pulse sequences and each PTIIL documented. Subgross measurements obtained during trimming aided localization and identification of PTIIL during microscopy. Histologic findings were categorized by descending clinical relevance: neoplastic, equivocal, non-neoplastic, within normal limits (WNL). Based on in vivo imaging resolution limits, histologic findings were ≥3 mm in at least one dimension and ≥3 mm apart. Surgical margins served as control tissue for PTIILs. Eighty-one of 87 PTIIL were examined histologically; 13 were neoplastic, 16 equivocal, and 28 non-neoplastic; 24 had no identified histologic correlate. Two neoplastic and 10 equivocal findings were located outside of PTIILs but none of them were located in sections of surgical margins. Computation of a simple confusion matrix yielded fair sensitivity (70.4%) and low specificity (59.7%) for prediction of PTIIL by histologic findings. After combining instances of normal microanatomy with non-neoplastic histologic findings, specificity increased (85.1%) and sensitivity decreased (35.8%). The protocol is a blueprint for targeting PTIIL for microscopic examination but may benefit from further refinement.

The appearance of canine insulinoma on dual phase computed tomographic angiography.

To further evaluate the appearance of insulinoma in dogs on dual-phase CT angiography, given the disparity of findings in recent publications. To establish whether CT angiographic localisation of insulinoma correlates with surgical findings. Single centre study of dogs with a final diagnosis of insulinoma which underwent abdominal CT angiography. Scans were retrospectively re-evaluated for specific features by two board-certified veterinary radiologists. These findings were also subsequently compared to surgical and histopathological reports to determine the accuracy of lesion localisation on CT. Thirty-five cases were included in final analysis, with pancreatic nodules identified in 33. Twenty-one were confirmed as insulinoma with histopathology. Jack Russell Terriers were over-represented. Twenty of 21 cases with confirmed insulinoma and 27 of 33 overall showed hyperattenuation in the arterial phase. The mean size of pancreatic insulinoma on CT was 15.1 mm, and 18.2% were larger than 20 mm. Eighteen of 21 confirmed and eight of 12 suspected insulinomas caused a deformation of the pancreatic shape, with two only identified as a result of this feature as these lesions were isoattenuating throughout the study. Pancreatic insulinoma location at surgery matched that described on the CT images in 17 of 19 cases where location was described in the surgical report. In contrast to recent publications, this study suggests hyperattenuation of insulinomas in the arterial phase is a predominant feature, and that hypoattenuation or isoattenuation are much less common. CT angiography is accurate in prediction of lesion location before surgery in most cases.

Correlation between Spot Sign and Intracranial Hemorrhage Expansion on Dual-Phase CT Angiography.

Purpose: Expansion of intracranial hemorrhage (ICH) is an important predictor of poor clinical outcome. ICH expansion can be predicted with a spot sign on computed tomographic angiography (CTA). We aimed to evaluate the correlation between spot signs on CTA and ICH expansion on dual-phase CTA. Methods: Patients with spontaneous ICH between January 2017 and April 2019 who underwent an initial CT, dual-phase CTA, and a subsequent CT were retrospectively identified. ICH expansion was defined as volume growth of >33% or >6 mL. We analyzed the presence and change in size of the spot sign in the first phase and second phase CTA. Also, we divided the morphological status of the spot sign, such as a dot-like lesion or linear contrast extravasation, in the first and second phase CTA. Results: A total of 206 patients, including 38 (18.5%) with ICH expansion and 45 (21.8%) with a spot sign, qualified for analysis. Of patients with a spot sign, 26 (57.8%) had ICH expansion on subsequent CT. Increased size of a spot sign in second-phase CTA was more frequent in the ICH expansion group than in the no-expansion group (96.2% vs. 52.6%, p < 0.001). First visualization of a spot sign in the second phase was more common in the no-expansion group than in the ICH expansion group (47.4% vs. 3.8%, p < 0.001). The morphological patterns of a spot sign between the two groups were not significantly different. Conclusion: Spot signs on dual-phase CTA have different sizes and morphological patterns. Increased size of a spot sign in the second phase of CTA can help identify patients at risk for ICH expansion.

Dual-Phase Computed Tomography Angiography Enhances Detection of Contrast Extravasation in Subarachnoid Hemorrhage

Contrast-enhanced computed tomography angiography (CTA) can be used to detect contrast extravasation in intracerebral hemorrhage. However, investigation for contrast extravasation in subarachnoid hemorrhage (SAH) is insufficient. We evaluated the efficacy of dual-phase CTA to improve evaluation of contrast extravasation in SAH. We retrospectively evaluated 35 patients with SAH who underwent contrast-enhanced dual-phase CTA within 24 hours from onset. The second-phase scan was performed 8 or 15 seconds following the usual CTA. The frequency of contrast extravasation was compared between phases. We also recorded the time from onset,coma level, interventional treatment, and early mortality. Of 35 patients (22.9%) with SAH, 8 showed contrast extravasation in the second phase compared with 3 in the first phase. Contrast extravasation was correlated with clinical coma level (P < 0.05), and all contrast extravasation was found within 6 hours from onset. Early mortality, treatment decision, and hematoma distribution type did not correlate with existence of contrast extravasation. We also observed 4 cases of secondary subpial hematoma due to SAH, with 3 showing extravasation in both phases. Dual-phase CTA with a short interval enhances detection frequency of contrast extravasation in SAH and might be a better evaluation tool for SAH.

Dual-phase CT angiography for presurgical planning in patients with vessel-depleted neck.

Microvascular reconstruction in vessel-depleted necks is challenging due to limited availability of recipient vessels. We examine the utility of dual-phase CT angiography (CTA), which delineates both arteries and veins, for preoperative planning in such difficult cases. Retrospective chart review of a single surgeon from July 2013 to July 2017 in a tertiary referral center was performed. Patient characteristics, operative details, and surgical outcomes were examined. Thirteen patients met inclusion criteria. The operative plan was changed to a local flap for one patient as a result of imaging; free tissue transfer was performed for the remaining cases with 100% flap survival rate. Average operative time and ischemia time were 524 ± 110 minutes and 153 ± 47 minutes, respectively. Dual-phase CTA can evaluate potential venous and arterial recipient vessel and guide surgical explorations. As such, it may aid in presurgical planning for microvascular free tissue transfer in vessel-depleted necks.

Dual-phase computed tomography angiography of intestinal carcinoid tumor as a lead point for cecocolic intussusception in a dog.

In an 8-year-old Labrador Retriever with progressive anorexia, constipation, and depression, CT revealed intussusception of the cecum into the ascending colon and a small cecal mass showing strong enhancement on arterial phase. The ileocecocolic junction was surgically resected and histologically diagnosed as cecocolic intussusception with carcinoid tumor. The carcinoid tumor worked as a lead point of intussusception in this case. Dual phasic CT is useful to assess the presence of gastrointestinal tumors as lead points in old dogs with intussusception.

Dual-phase 16 slice CT angiography in stroke imaging: a poor man's multiphase study?

Multiphase CT angiography (CTA) in collateral assessment provides time-resolved cerebral angiograms of the intracranial vasculature, requiring a high-speed multidetector CT (MDCT) scanner with ≥ 64 slices. Unfortunately, many hospitals are equipped with lower speed MDCT scanners. Herein, we present our experience performing dual-phase CTA (d-CTA) on a 16 slice MDCT with a biphasic rate injection to grade intracranial collaterals as predictor of clinical outcome. 42 patients were evaluated with both dual-phase CTA (d-CTA) and single-phase CTA (s-CTA) for occluded anterior intracranial circulation and collaterals. They were treated with endovascular reperfusion. Univariate and multivariate analyses were performed to define the independent predictors for favorable outcome at 3months. Good collateral circulation status on d-CTA was associated with a lower median 24-h (5 vs. 7.5, p = 0.03) and discharge (2 vs. 4.6, p = 0.04) NIHSS. A logistic regression model showed that only age (OR 0.95, 95% CI 0.91-0.98, p = 0.03) and good collateral circulation status at d-CTA (OR 4.3, 95% CI 1.87-11.3, p < 0.01) were independent predictors of favorable functional outcome at 3months, but that s-CTA was not. The collateral status on d-CTA can be a useful predictor for clinical outcome in acute stroke patients. The proposed protocol adapted to a low-speed MDCT scanner could be of particular interest in hospitals without access to the more up-to-date technology.

Subpial Hematoma and Extravasation in the Interhemispheric Fissure with Subarachnoid Hemorrhage

A recent report on computed tomography (CT) findings of contrast extravasation in subarachnoid hemorrhage (SAH) with Sylvian hematoma suggests that the occurrence of the hematoma is secondary to bleeding in the subpial space. Our patient was in his sixties and was admitted to the hospital because of loss of consciousness (Glasgow Coma Scale E4V1M4). SAH was diagnosed in plain head CT, and growing hematomas were observed in the Sylvian and interhemispheric fissures following a subarachnoid hemorrhage. CT angiography (CTA) using a dual-phase scan protocol revealed contrast extravasation in both the fissures in the latter phase, and hematoma in the interhemispheric fissure contained multiple bleeding points. This case indicates that the occurrence of subpial hematoma such as Sylvian hematoma can be a secondary event following subpial bleeding from damaged small vessels elsewhere in the cranium. Instead of four-dimensional (4D) CT, the dual-phase CTA technique may help detect minor extravasations with usual helical CT scanner.

Dual-phase CT angiography through the port-catheter system for hepatic arterial infusion chemotherapy using multislice CT: assessment of system dysfunction and impact on predicting clinical problems

Hepatic arterial infusion (HAI) chemotherapy is being explored for treatment of malignant liver tumors. Maintenance of HAI systems is important for effective treatment. To prospectively evaluate the efficacy of dual-phase CT angiography through the port-catheter system for HAI chemotherapy. This study enrolled 47 patients receiving HAI chemotherapy for malignant liver tumors who underwent dual-phase CT angiography through the port-catheter system using multislice CT. Using maximum intensity projection images reconstructed from vascular-phase CT imaging, hepatic arterial patency and catheter location were assessed. Using a combination of vascular- and perfusion-phase CT imaging, system dysfunction and clinical problems were evaluated. Dual-phase CT angiography was conducted 156 times. Stenosis and obstruction of the hepatic artery and catheter dislodgment were observed seven times in four patients and four times in three patients, respectively. Diagnostic accuracy using vascular-phase CT imaging was 100%. In addition, development of collateral blood supply to the liver and extrahepatic perfusion to the stomach were observed three times in three patients and twice in two patients, respectively. Overall, system dysfunction occurred 16 times in 12 patients, and system correction and treatment modification were required 11 times in 10 patients. In assessing system dysfunction and predicting clinical problems, the accuracy of dual-phase CT imaging was 100%. Dual-phase CT angiography through the port-catheter system is helpful for assessing catheter system dysfunction and predicting clinical problems in HAI chemotherapy.

Role of MDCT Angiography in Selection and Presurgical Planning of Potential Renal Donors

The purpose of this study was to determine the prevalence and types of renal and extrarenal abnormalities that preclude renal donation or lead to alteration of the surgical approach on the basis of abdominal CT angiography (CTA) in a large group of potential renal donors. In this retrospective study, 654 potential renal donors undergoing dual-phase CTA were identified from January 2005 to January 2009. The CT reports were systemically reviewed by two radiologists to determine the presence of renal and extrarenal abnormalities. The operative notes of the renal donors were reviewed by one radiologist to determine whether the presence of renal pathology had affected the surgical approach. In the candidates who did not proceed to kidney donation, the reasons that precluded kidney donation were abstracted from the transplant database. Four hundred seventeen potential donors (269 men and 385 women; mean age, 44.0 years; age range, 17-79 years) proceeded to renal donation and 237 did not. The most common renal abnormalities were cysts (34%) and renal stones (4.4%). Renal artery disease was identified in 3.4% of potential donors, including renal artery stenosis, possible fibromuscular dysplasia, and renal artery aneurysm. Suspicious renal masses were incidentally found in 0.5% of potential donors. The most common extrarenal pathology was an incidental adrenal nodule (2.6%). Other significant extrarenal pathology identified included gallbladder mass (0.2%), Crohn disease (0.2%), ovarian mass (0.2%), and possible sarcoidosis (0.2%). Although renal and extrarenal abnormalities were present in 41% of potential renal donors, abnormalities seen on CT only contributed to exclusion of 27 potential donors (4.1%). The most common reason for exclusion was the presence of renal stones or scarring (1.8%). Significant CT findings also contributed to the selection of the right kidney in 29 donors, most commonly due to presence of ipsilateral vascular disease or complex left vascular anatomy. Renal parenchymal and vascular abnormalities are common in asymptomatic potential kidney donors. Although most of these represent incidental CT findings, abnormalities can exclude potential renal donors and alter the surgical approach in a small minority of cases.

Detection of Type II Endoleak After Endovascular Aortic Repair: Comparison Between Magnetic Resonance Angiography and Blood-Pool Contrast Agent and Dual-Phase Computed Tomography Angiography

Detection of Type II Endoleak After Endovascular Aortic Repair: Comparison Between Magnetic Resonance Angiography and Blood-Pool Contrast Agent and Dual-Phase Computed Tomography Angiography

Preoperative Visualization of the Artery of Adamkiewicz by Dual-Phase CT Angiography in Patients with Aortic Aneurysm

To improve our ability to visualize the Adamkiewicz artery (AKA), we developed a modified intravenous CT angiography technique, which we refer to as right atrial CT (RA-CT) angiography. In this study, AKA detection rate and visualization of the arterial continuity from the aorta to the anterior spinal cord artery (ASA) was evaluated using RA-CT angiography.We performed RA-CT angiography in 110 patients with abdominal, thoracic descending, or thoracoabdominal aortic aneurysms. In RA-CT angiography, contrast medium with a high iodine concentration (370 mg/dl) was injected twice into the right atrium at a high injection rate (8.0 ml/sec), and two CT scans, starting at 20 sec after the first injection and at 35 sec after the second injection, respectively, were performed. All CT images were obtained using an 8- or 16-detector CT scanner at a slice thickness of 0.625 mm. The AKA was defined as the largest radiculomedullary artery with a characteristic hairpin turn, and with continuity from the aorta to the ASA.The AKA with hairpin turn was detected in all patients (100%), and continuity from the aorta to the ASA was confirmed in 99 of the 110 patients (90.0%). The AKA arose between Th8 and L1 in 86 of these patients (86.8%), and originated from the left side in 71 patients (71.7%).RA-CT angiography may be useful for visualizing the AKA and the arterial continuity from the aorta to the ASA in patients with aortic aneurysm, although the use of more advanced CT machines will provide safe and easy identification of the AKA and arterial continuity with a small amount of contrast medium and a single scan.

Detection of Type II Endoleak After Endovascular Aortic Repair: Comparison Between Magnetic Resonance Angiography and Blood-Pool Contrast Agent and Dual-Phase Computed Tomography Angiography

This prospective study was designed to assess the diagnostic value of magnetic resonance angiography (MRA) with blood-pool contrast agent (gadofosveset) in the detection of type-II endoleak after endovascular aortic repair (EVAR). Thirty-two patients with aortic aneurysms who had undergone EVAR were included in this study. All patients were examined by dual-phase computed tomography angiography (CTA) as well as MRA with gadofosveset in the first-pass and steady-state phases. Two independent readers evaluated the images of CTA and MRA in terms of endoleak type II, feeding vessel, and image quality. Median follow-up-time after EVAR was 22 months (range 4 to 59). Endoleak type II was detected by CTA in 12 of 32 patients (37.5%); MRA detected endoleak in all of these patients as well as in another 9 patients (n = 21, 65.6%), of whom the endoleaks in 6 patients showed an increasing diameter. Most endoleaks were detected in the steady-state phase (n = 14). The decrease in diameter of the aneurysmal sac was significantly greater in the patients without a visible endoleak that was visible on MRA (P = 0.004). In the overall estimation of diagnostic accuracy, MRA was judged superior to CTA in 66% of all examinations. MRA with gadofosveset appeared superior to CTA, and has higher diagnostic accuracy, in the detection of endoleak after EVAR.

Anatomic Variations of the Celiac Trunk and the Left Gastric Vein Assessing by Dual-Phase CT Angiography for Safety Laparoscopic Gastrectomy

Purpose: The purpose of this study is to evaluate clinical anatomic variations of the left gastric vein brunch by portal venography using 64-row MDCT and to minimize surgical blood loss during laparoscopic gastrectomy. Method and Materials: One hundred and twenty-six consecutive patients of digestive disease were enrolled (82 male; mean age, 66 years; 92 gastric cancer, cancer, 10 gastric GIST, 7 colorectal cancer, and 17 others). Scanning was performed using a 64-row MDCT scanner with a 0.5mm slice thickness and a pitch factor of 0.8 after intravenous injection of contrast medium at a rate of 4.0ml/sec in a total volume of 140ml.

COMPARISON OF TRANSPLENIC MULTIDETECTOR CT PORTOGRAPHY TO MULTIDETECTOR CT‐ANGIOGRAPHY IN NORMAL DOGS

We evaluated transplenic injection of iodinated contrast medium for computed tomography (CT) assessment of the portal vasculature. Specific aims were to: (1) establish a protocol for transplenic transplenic CT portography using a 40-row multidetector scanner; (2) compare transplenic CT portography to dual-phase CT angiography in terms of image quality, opacification of the portal system, and contrast enhancement of the portal vasculature and liver; (3) compare personnel exposure during transplenic CT portography and transplenic portal scintigraphy. Seven juvenile dogs underwent transplenic portal scintigraphy, CT angiography, and transplenic CT portography. Transplenic portal scintigraphy and CT angiography were performed using previously established protocols. For transplenic CT portography, a 20- or 22 gauge needle attached to an extension set was placed into the splenic parenchyma using CT guidance. Iodinated contrast medium (175 mg I/ml) was administered, and CT acquisition was started at the time of the injection. Transplenic CT portography was simple, rapid and provided more intense enhancement of the splenic and portal veins, with a lower contrast medium dose (median dose: 525 mg I for transplenic CT portography, 7700 mg I for CT angiography), but caused inconsistent intrahepatic portal branches and parenchymal opacification due to streamlining and streak artifacts. Despite significantly lower attenuation values in the portal vein, CT angiography provided sufficient enhancement for vessel identification and more consistent parenchymal hepatic enhancement. Personnel radiation exposure rate was higher during transplenic CT portography (0.0725 mSv/min) compared with transplenic portal scintigraphy (0.000125 mSv/min). As transplenic CT portography requires an average injection time of 1 min per study; over 650 [corrected] studies must be performed before reaching the maximum permissible whole body dose of 0.05 [corrected] Sv.