Triphasic Helical Computed Tomography Research Articles

Evaluation of triphasic helical computed tomography of the kidneys in clinically normal dogs

To determine computed tomography (CT) delay times by use of a sequential scan and identify the normal enhancement pattern in each phase of a triphasic CT scan of the kidneys in dogs. 14 healthy Beagles. A sequential CT scan was used for investigating delay time, and a triphasic helical CT scan was used for identifying the normal enhancement pattern and determining Hounsfield unit values in the kidneys of dogs. In the cine scan (single-slice dynamic scan), the optimal delay times were 10 seconds in the corticomedullary phase and 44 seconds in the nephrographic phase, after contrast medium injection. By use of triphasic CT images, Hounsfield unit values were acquired in each phase. Triphasic CT of the kidneys in clinically normal dogs was established by acquisition of delay times in a cine scan and may become an important imaging modality in the diagnosis of renal diseases and in treatment planning in dogs.

Preoperative staging of renal cell carcinoma using triphasic helical computed tomography

ObjectiveTo determine if staging of renal cell carcinoma (RCC) can be predicted from preoperative triphasic helical computed tomography (CT) findings. Patients and methodsWe reviewed the triphasic helical CT scans of 48 consecutive patients with pathologic diagnosis RCCs. All tumors were staged according to the 2002 version of TNM staging system. The preoperative radiologic staging was compared with postoperative pathologic staging. Agreement between the two staging systems was determined using the kappa test. ResultsComparison between triphasic helical CT staging and pathologic staging showed harmony in all lesions in stage T1a, and T1b. Triphasic helical CT over diagnosed two cases of stage T1b regarded as stage T3a while agreement was noted in all cases of stage T2. Harmony was noted between triphasic helical CT and pathologic staging in two lesions stage T3a, four lesions in stage T3b, and two lesions stage T4. The agreement between triphasic helical CT and pathologic T stages was perfect (K=0.941). Forty-two cases were staged N0, one case was N1, and five cases were staged N2 by triphasic CT. Three cases were over staged, and six cases were under staged while, 39 were correctly N staged. The agreement between triphasic helical CT and pathologic N staging was poor (K=0.33). ConclusionThe agreement between the preoperative triphasic helical CT staging and postoperative pathologic T staging is perfect, while agreement in N stages is poor. So T staging of RCC can be predicted from triphasic helical CT findings while N staging cannot be predicted preoperatively.

Split renal function measured by triphasic helical CT

Purpose To present a method for calculating split renal function solely from routine triphasic helical computed tomography (CT). Subjects and methods We retrospectively included 26 adult patients who received renal scintigraphy and triphasic CT within 4 weeks in the years 2003 and 2004. All scans were performed using a standard abdominal protocol. Split renal function was calculated as relative single-kidney glomerular filtration rate (GFR) using a simplified “two-point Patlak plot” technique. As a reference method, split renal function was determined from renal scintigraphy using the standard technique. Results Linear correlation between the two methods was r = 0.91, split renal function (CT) = 0.0266 + 0.9573 × split renal function (scintigraphy). Conclusion Split renal function can be measured accurately by minimally extended triphasic CT.

The Role of Late-Phase Pulse Inversion Harmonic Imaging in the Detection of Occult Hepatic Metastases

The purpose of this study was to investigate the efficacy of late-phase pulse inversion harmonic imaging (PIHI) in detecting occult metastases and to compare the results with helical computed tomography (CT) in a group of patients whose fundamental liver sonographic results were normal. Thirty-two patients (21 women and 11 men; age range, 20-87 years) with a known primary malignancy were enrolled in the study. The patients were evaluated with conventional sonography, unenhanced PIHI, and PIHI 3 minutes after the injection of Levovist (SH U 508A; Schering AG, Berlin, Germany). All patients also underwent triphasic helical CT within 1 week after sonography. In 1 patient, mangafodipir-enhanced magnetic resonance imaging was performed as part of the clinical workup. After Levovist injection, in 4 (12.5%) of 32 patients, at least 1 hypoechoic lesion was detected by PIHI; multiple lesions were shown in 1 patient. The mean diameter of newly detected lesions was 12 mm. Triphasic helical CT also showed all of the lesions that were detected by PIHI. The diagnoses were confirmed by biopsy and CT findings in 2 patients and by the typical CT and magnetic resonance imaging findings in 1 patient. For the fourth patient, the diagnosis was confirmed by follow-up and CT. Conclusions. Late-phase PIHI is comparable to helical CT for detecting occult hepatic metastases, but it protects patients from the potentially hazardous effects of radiation and iodinated contrast agents. Further series involving a larger number of patients are needed to determine its place in the evaluation of cancer staging and treatment planning.

Triphasic helical CT in Budd–Chiari syndrome: patterns of enhancement in acute, subacute and chronic disease

To retrospectively evaluate helical computed tomography (CT) findings in a series of consecutive patients with Budd-Chiari syndrome. Patterns of enhancement observed at contrast-enhanced helical CT in 10 consecutive patients (six women, four men; aged 27-51 years) with either acute, subacute or chronic Budd-Chiari syndrome were retrospectively evaluated along with the status of the hepatic veins. All patients underwent triphasic helical CT (10 mm beam collimation, 7 mm rec. intervals, 120 kV, 200-250 mA, pitch = 1.0) performed at 20-25, 70-75 and 300 s after i.v. bolus (3 ml/s) injection of 150 ml iodinated non-ionic contrast media. Abnormal patterns of enhancement were identified in eight patients. In all patients with acute Budd-Chiari disease (3/3) abnormal arterial enhancement of the caudate lobe, the so-called "fan-shaped pattern" was observed, whereas visible venous thrombosis was only depicted in two. Conversely, a "patchy pattern" of enhancement was observed in five out of seven patients with either sub-acute (2) or chronic Budd-Chiari disease (5) along with a strip-like appearance or lack of visualization of hepatic veins. The "fan-shaped" pattern of enhancement represent a characteristic finding of acute Budd-Chiari disease, and it may help to suggest the correct diagnosis even in absence of visible venous thrombosis.

Glomerular filtration rate measured by using triphasic helical CT with a two-point Patlak plot technique.

To determine the accuracy of the two-point Patlak plot in the calculation of glomerular filtration rate (GFR). Fifty patients without acute renal disorder were included. GFR was calculated by using a two-point Patlak plot technique. The computed tomography (CT) protocol consisted of a plain examination followed by two contrast material-enhanced examinations in the arterial and portovenous phase. Each examination included the entire kidneys and was performed after injection of 120 mL iopromide and 300 mg of iodine per milliliter given per 75 kg of body weight. All examinations were performed with a standard abdominal protocol. Section thickness was 4 x 2.5 mm, and table advance was 12.5 mm. Bolus triggering commenced 10 seconds after the start of contrast medium injection. Twelve dynamic scans were obtained with reduced tube current every 3 seconds to obtain sufficient arterial input function data. Correction for hematocrit level was made by using the unenhanced attenuation of the aorta. As a reference method, plasma clearance of the contrast medium injected for CT was calculated from three iodine plasma concentration measurements obtained 3, 4, and 5 hours after injection. Linear correlation was performed. GFR was calculated from CT data in 48 patients. Two patients were excluded because of breathing errors. Mean GFR was 80 mL/min (range, 17-153 mL/min) as measured with iopromide plasma clearance and 82 mL/min (range, 28-148 mL/min) as measured with CT. Linear correlation between the two methods was r = 0.889; GFR calculated with the two-point Patlak plot was equal to 15 plus 0.83 times GFR (plasma clearance). The mean difference between GFRs as determined with the two methods was -1.2 mL/min (95% CI: -27.1, 24.6). Total GFR can be measured accurately with minimally extended triphasic CT in patients without acute renal disorder by using a two-point Patlak plot technique.

Epithelioid Hemangioendothelioma of the Liver: Helical CT Findings

Purpose: To describe the morphologic features and enhancement patterns of the helical computed tomography (CT) observed in patients with epithelioid hemangioendothelioma (EH) of the liver. Materials and Methods: Seven patients (four men and three women; mean age, 41 years) with pathologically proven EHs underwent monophasic (n=2), biphasic (n=2) or triphasic (n=3) helical CT, and the findings were retrospectively analysed. The morphologic features to which attention was directed were tumor number, size, location, shape, margin, surface, the presence of adjacent capsular retraction, vascular encasement and confluent mass formation, while the enhancement pattern was examined in terms of the appearance and degree of enhancement during the arterial or portal phase, and enhancement change during the portal and equilibrium phases. Results: Six patients had multiple tumors, and one had a single lesion. The maximon diameter of these tumors ranged from 0.5 to 12.0 (mean, 3.2) cm, and almost all occurred in the peripheral portion of the liver. The shape, margin and surface features of the tumors varied: in four patients, the margin was poorly defined and the surface was smooth, while in five, adjacent capsular retraction was observed. Vascular encasement was noted in five of six patients with hepatic vessels abutting the tumors, and in all three who were follow up, the growth pattern involved confluent mass formation. In all patients, many tumors showed either nodular (n=3) or irregular (n=4) peripheral enhancement. In all five patients who underwent multiphasic CT, centripetal enhancement was demoustrated. Conclusion: Our results disclosed that most patients with EH had multiple tumors, and that almost all were located in the peripheral portion of the liver and involved capsular retraction. The other common CT findings were vascular encasement and a centripetal enhancement pattern. When these CT findings are observed in patients with hepatic tumors, EH should be included in the differential diagnosis.

Preoperative use of 3D volume rendering to demonstrate renal tumors and renal anatomy.

With increased us of computed tomography (CT) and abdominal ultrasonography, the indications for nephron-sparing surgery are also increasing. Triphasic helical CT and three-dimensional (3D) volume rendering can be combined into a single noninvasive test to delineate renal tumors and normal and complex renal anatomy prior to nephron-sparing surgery. This combination technique has provided accurate and very useful for both preoperative and intraoperative planning by demonstrating renal position, tumor location and depth of tumor extension into the kidney, relationship of the tumor to the collecting system, and renal vascular anatomy. Knowledge of the position of the kidney relative to the lower rib cage, iliac crest, and spine helps in planning the initial surgical incision. By depicting tumor location and depth of extension, helical CT with 3D volume rendering helps ensure complete tumor excision and conservation of adjacent normal renal parenchyma. Depiction of the relationship of the tumor to the collecting system helps anticipate further tumor extension and minimize postoperative complications. Identification of normal renal vasculature and anatomic variants can help minimize ischemic injury and intraoperative bleeding. Radiologists should be familiar with current indications for nephron-sparing surgery and understand what information is required prior to surgery. The authors underscore the value of helical CT with 3-dimensional imaging in the approach to nephron-sparing surgery for localized renal cancers. The authors suggest, and I agree, that this technique can markedly reduce the need for invasive arteriographic imaging in these patients. The ability of this technique to identify the renal vasculature may prove particularly useful in cases where difficult partial nephrectomy is contemplated. Robert Flanigan, M.D.

Multi-detector row helical CT angiography of hepatic vessels: depiction with dual-arterial phase acquisition during single breath hold.

To determine by using multi-detector row computed tomography (CT), in a triphasic hepatic dynamic study, which included single breath-hold dual-arterial phase acquisition, the accuracy and frequency of visualization of the small hepatic arterial and portal venous anatomy with angiographic correlation. In 62 patients, pre- and postcontrast triphasic helical CT were performed by using a multi-detector row CT scanner, with 2.5-mm detector row collimation, at a pitch of 6. The first and second arterial phases were performed during a single breath hold. One reader, blinded to the results of the angiography, reviewed the first arterial phase images on a cine display to assess hepatic arterial anatomy. Visualization of the portal vein and its branches was assessed by using second arterial and portal venous phase images. Major arterial trunks (celiac, hepatic, superior mesenteric, and left gastric) were depicted in all cases. Visualization of small arteries was as follows: right and left hepatic, 62 (100%) of 62; middle hepatic, 52 (87%) of 60; cystic, 47 (90%) of 52; right gastric, 50 (89%) of 56; and right and left inferior phrenic, 57 (92%) and 55 (89%) of 62, respectively. Subsegmental or more peripheral branches of the portal vein were depicted in 83% of cases during the second arterial phase and in 96% during the portal phase. There was no difference in degree of visualization in these two phases. Multi-detector row CT angiography was able to depict the hepatic vascular anatomy.

Enhancement Pattern of Hepatocellular Carcinoma on Triphasic Helical CT: Quantitative Study

Purpose: To assess the enhancement pattern of hepatocellular carcinoma (HCC), as seen on triphasic helical dynamic computed tomography (CT) by measuring the attenuation value. Materials and Methods: Triphasic helical dynamic CT scans of the liver in 94 patients (M:F=73:21; aged 33-81 years) with HCC were evaluated. The condition was confirmed on the basis of histologic (n=28) or clinical (n=66) findings. Scans were obtained at 30, 70, and 180 seconds after the start of contrast material injection, the attenuation values of the solid portion of the HCC and adjacent normal liver parenchyma being measured during the three phases. Enhancement patterns of the HCC nodule and adjacent liver parenchyma were analyzed, and the size of HCCs, the presence or absence of portal vein thrombosis, and the Child classification were also determined. Results: The mean attenuation values of HCC were 69 HU during the arterial phase, 80 HU during the portal phase, and 65 HU during the delayed phase, while those of liver parenchyma were 48 HU, 81 HU and 72 HU, respectively. In 71.3% of cases (67/94), maximum enhancement occurred during the portal phase. Decreased tumor attenuation after peak enhancement was seen in 71.3% of lesions (67/94, Group I). while in 28.7% (27/94, Group II) attenuation showed no significant decrease. There were no statistically significant differences in the size of HCCs, portal vein thrombosis or Child classification between the two groups (p>0.05). Conclusion: On triphasic helical dynamic CT, the mean attenuation value of HCCs was highest during the portal phase. Over time, the majority of HCCs showed a decreased attenuation value.

Preoperative use of 3D volume rendering to demonstrate renal tumors and renal anatomy.

With increased use of computed tomography (CT) and abdominal ultrasonography, the indications for nephron-sparing surgery are also increasing. Triphasic helical CT and three-dimensional (3D) volume rendering can be combined into a single noninvasive test to delineate renal tumors and normal and complex renal anatomy prior to nephron-sparing surgery. This combination technique has proved accurate and very useful for both preoperative and intraoperative planning by demonstrating renal position, tumor location and depth of tumor extension into the kidney, relationship of the tumor to the collecting system, and renal vascular anatomy. Knowledge of the position of the kidney relative to the lower rib cage, iliac crest, and spine helps in planning the initial surgical incision. By depicting tumor location and depth of extension, helical CT with 3D volume rendering helps ensure complete tumor excision and conservation of adjacent normal renal parenchyma. Depiction of the relationship of the tumor to the collecting system helps anticipate further tumor extension and minimize postoperative complications. Identification of normal renal vasculature and anatomic variants can help minimize ischemic injury and intraoperative bleeding. Radiologists should be familiar with current indications for nephron-sparing surgery and understand what information is required prior to surgery.

Acute occlusion of the middle cerebral artery: early evaluation with triphasic helical CT--preliminary results.

To evaluate use of triphasic helical computed tomography (CT) for early diagnosis of occlusion and assessment of ischemia in cases of acute middle cerebral arterial occlusion. Thirty-five patients with acute ischemia underwent triphasic helical CT within 6 hours after symptom onset. Early arterial, perfusion, and delayed phase CT scans were obtained 18, 30, and 80 seconds, respectively, after contrast material administration. Eighteen patients had proximal middle cerebral arterial occlusion diagnosed at magnetic resonance (MR) or digital subtraction angiography. Follow-up CT or MR imaging was performed in all patients. Two independent observers interpreted images for signs of arterial occlusion, collateral vessels, and the ischemic zone. One observer found at least one of three signs in 17 of the 18 patients with occlusion, and the other found at least one sign in all 18: Early decreased arterial contrast enhancement was seen by both observers in 11 patients (kappa = 0.77), a nonenhancing arterial segment was seen by the two observers in 12 and 14 (kappa = 0.73), and delayed asymmetric arterial enhancement was seen in 13 and 16 (kappa = 0.49). Triphasic CT findings of the ischemic zone were consistent with follow-up CT or MR imaging findings in seven of 12 patients. Triphasic helical CT is useful for early diagnosis of acute proximal middle cerebral arterial occlusion and assessment of the ischemic zone.