Pancreatic malignancy: value of arterial, pancreatic, and hepatic phase imaging with multi-detector row CT

PURPOSE: To assess the value of arterial, pancreatic, and hepatic phase imaging at multi-detector row computed tomography (CT) of the pancreas for pancreatic malignancy. MATERIALS AND METHODS: Thirty-nine patients suspected of having resectable pancreatic adenocarcinoma underwent triple-phase multi-detector row CT. Images obtained during each phase were interpreted by one radiologist who evaluated presence of tumor, vascular invasion, and flow artifacts in the superior mesenteric vein and measured attenuation of tumor, normal pancreas, aorta, and superior mesenteric vein. Results were compared with histologic, follow-up, and correlative imaging findings. RESULTS: Mean tumor-to-gland attenuation difference was greatest on images obtained in the pancreatic phase (42 HU) versus that on those obtained in the hepatic phase (35 HU) and in the arterial phase (25 HU). For tumor detection, sensitivity of the images obtained in pancreatic (0.97 [29 of 30]) and hepatic (0.93 [28 of 30]) phases was superior to that of those obtained in arterial phase (0.63 [19 of 30]) (P < or =.008). For vascular invasion detection, sensitivity of images obtained in the hepatic phase (0.83) was better than that of those obtained in the pancreatic (0.58) and arterial (0.25) phases. Images obtained in the pancreatic phase demonstrated more flow artifacts and decreased attenuation in the superior mesenteric vein, compared with the artifacts revealed on images obtained in the hepatic phase. CONCLUSION: Routine acquisition of images in the arterial phase is unnecessary for detection of pancreatic adenocarcinoma. Images of the pancreas obtained in the hepatic phase with multi-detector row CT most accurately display vascular invasion.     

Evaluation of optimal timing of arterial phase imaging for the detection of hypervascular hepatocellular carcinoma by using triple arterial phase imaging with multidetector-row helical computed tomography

PURPOSE: We evaluated the optimal timing of arterial phase imaging for detection of hypervascular hepatocellular carcinoma by using triple arterial phase imaging with multidetector-row helical computed tomography. MATERIALS AND METHODS: Forty-nine patients with 90 hypervascular hepatocellular carcinomas (3 to 50 mm in diameter; mean, 18.7 mm) underwent triple arterial phase imaging of the whole liver using a multidetector-row helical computed tomography. At 20 seconds, 30 seconds, and 40 seconds after intravenous administration of 100 mL of 300 mgI/mL of nonionic contrast medium at a rate of 4 mL/s, early, middle, and late arterial phase images were obtained serially during a single breath-hold with an interscan delay of 5 seconds. Detector-row configurations of 4 mm x 4, scan pitch of 5.5, and scan time of 5 seconds for each phase were used. Forty prospective reconstruction images of 5-mm thickness for each phase were obtained. The images from each phase were interpreted separately for detection of hypervascular hepatocellular carcinoma by 3 observers independently who were unaware of tumor burden in the liver. Sensitivity, positive predictive value, and area under the receiver operating characteristic curve values for each arterial phase were calculated and compared statistically. RESULTS: The mean sensitivity and positive predictive values for hypervascular hepatocellular carcinoma diagnosis of blind readers were 37% and 87% for the early arterial phase, 73% and 85% for the middle arterial phase, and 49% and 81% for the late arterial phase, respectively. The middle arterial phase imaging showed significantly superior sensitivity compared with the early and late arterial phase for detecting hepatocellular carcinoma (P < 0.05). Mean area under the receiver operating characteristic curve value of the middle arterial phase imaging (0.84) was significantly higher that that of the early (0.56) or late arterial phase (0.62; P < 0.05). CONCLUSION: If a single arterial phase is used for diagnosis of hypervascular hepatocellular carcinoma, the middle phase (delay time of 30 seconds) is optimal.     

Ultrasonography and computed tomography in pancreatic malignancy

Previous reports have shown that ultrasonography (US) is inferior to computed tomography (CT) in detecting pancreatic carcinoma. Since our recent observations suggested the opposite we re-evaluated the accuracy of these two methods. Among 36 patients with malignant tumours the US was normal in one, in 4 it showed only secondary signs of tumour, and in 31 it revealed the tumour. The corresponding figures for CT were 2, 9 and 25, respectively. The conclusion is that US should be considered the primary method for imaging the pancreas.     

Optimized scan delay for late hepatic arterial or pancreatic parenchymal phase in dynamic contrast-enhanced computed tomography with bolus-tracking method

Objectives:To determine the optimal scan delay corresponding to individual hemodynamic status for pancreatic parenchymal phase in dynamic contrast-enhanced CT of the abdomen.Methods:One hundred and fourteen patients were included in this retrospective study (69 males and 45 females; mean age, 67.9 ± 12.1 years; range, 39–87 years). These patients underwent abdominal dynamic contrast-enhanced CT between November 2019 and May 2020. We calculated and recorded the time from contrast material injection to the bolus-tracking trigger of 100 Hounsfield unit (HU) at the abdominal aorta (s) (Time_TRIG) and scan delay from the bolus-tracking trigger to the initiation of pancreatic parenchymal phase scanning (s) (Time_SD). The scan delay ratio (SDR) was defined by dividing the Time_SD by Time_TRIG. Non-linear regression analysis was conducted to assess the association between CT number of the pancreas and SDR and to reveal the optimal SDR, which was ≥120 HU in pancreatic parenchyma.Results:The non-linear regression analysis showed a significant association between CT number of the pancreas and the SDR (p < 0.001). The mean Time_TRIG and Time_SD were 16.1 s and 16.8 s, respectively. The SDR to peak enhancement of the pancreas (123.5 HU) was 1.00. An SDR between 0.89 and 1.18 shows an appropriate enhancement of the pancreas (≥120 HU).Conclusion:The CT number of the pancreas peaked at an SDR of 1.00, which means Time_SD should be approximately the same as Time_TRIG to obtain appropriate pancreatic parenchymal phase images in dynamic contrast-enhanced CT with bolus-tracking method.Advances in knowledge:The hemodynamic state is different in each patient; therefore, scan delay from the bolus-tracking trigger should also vary based on the time from contrast material injection to the bolus-tracking trigger. This is necessary to obtain appropriate late hepatic arterial or pancreatic parenchymal phase images in dynamic contrast-enhanced CT of the abdomen.     

Mimicks of pancreatic malignancy in patients with chronic pancreatitis: correlation of computed tomography imaging features with histopathologic findings

Differentiation of chronic pancreatitis and pancreatic carcinoma can be a clinical and radiologic dilemma. Several patients with chronic pancreatitis can undergo unnecessary major abdominal surgery for benign lesions. This pictorial review illustrates the computed tomographic findings and histopathologic features of lesions mimicking pancreatic neoplasm in patients with chronic pancreatitis. Several benign lesions can simulate pancreatic malignancy in patients with chronic pancreatitis. Knowledge of the computed tomographic appearance of these benign entities is important to prevent unnecessary surgeries.     

Efficacy of double arterial phase dynamic magnetic resonance imaging with the sensitivity encoding technique versus dynamic multidetector-row helical computed tomography for detecting hypervascular hepatocellular carcinoma

Purpose  The aim of this study was to evaluate the efficacy of double arterial phase dynamic magnetic resonance imaging (MRI) with the sensitivity encoding technique (SENSE dynamic MRI) for detection of hypervascular hepatocellular carcinoma (HCC) in comparison with double arterial phase dynamic multidetector-row helical computed tomography (dynamic MDCT). Materials and methods  A total of 28 patients with 66 hypervascular HCCs underwent both double arterial SENSE dynamic MRI and dynamic MDCT. The diagnosis of HCC was based on surgical resection (n = 7), biopsy (n = 10), or a combination of CT during arterial portography (CTAP), CT during hepatic arteriography (CTA), and/or the 6-month follow-up CT (n = 49). Based on alternative-free response receiving operating characteristic (ROC) analysis, the diagnostic performance for detecting HCC was compared between double arterial phase SENSE dynamic MRI and double arterial phase dynamic MDCT. Results  The mean sensitivity, positive predictive value, and mean Az values for hypervascular HCCs were 72%, 80%, and 0.79, respectively, for SENSE dynamic MRI and 66%, 92%, and 0.78, respectively, for dynamic MDCT. The mean sensitivity for double arterial phase SENSE dynamic MRI was higher than that for double arterial phase dynamic MDCT, but the difference was not statistically significant. Conclusion  Double arterial phase SENSE dynamic MRI is as valuable as double arterial phase dynamic MDCT for detecting hypervascular HCCs.     

Renal artery aneurysm: diagnosis and surveillance with multidetector-row computed tomography

Purpose: To investigate the prevalence of renal artery aneurysms, and to assess the value of multidetector-row computed tomography (MDCT) in diagnosing renal artery aneurysms.

Material and Methods: Altogether, 862 patients underwent arterial-phase contrast-enhanced CT scan of the abdomen in the period November 2003 to October 2005. A search for renal artery aneurysms was performed in our reporting system and revealed six patients with renal artery aneurysm (RAA).

Results: The incidence of RAA was 0.7%. All renal artery aneurysms were solitary, located in the main trunk or the first branch of the renal artery, with sizes from 1.5 cm to 3.4 cm. Five aneurysms were saccular, one fusiform. No underlying thrombosis was seen. Extensive calcification was found in one aneurysm. Three aneurysms were diagnosed using axial images, while three aneurysms were only displayed by volume rendering and maximum-intensity projection images.

Conclusion: This study demonstrates a 0.7% incidence of renal artery aneurysms in a total of 862 patients. MDCT has an important role in detecting and assessing renal artery aneurysms. Some aneurysms can only be displayed by post-processing techniques such as volume rendering and maximum-intensity projection.     

Assessment of regional left ventricular function with multidetector-row computed tomography versus magnetic resonance imaging

This study compares quantitative and qualitative information on global and regional left ventricular (LV) function obtained with multidetector-row computed tomography (MDCT) with that obtained with magnetic resonance imaging (MRI) in patients with a high prevalence of LV wall motion abnormalities. Thirty patients (19 male, 63.7+/-15.1 years) with myocardial infarction (n=12), coronary artery disease (n=9), arrhythmogenic right ventricular cardiomyopathy (n=6), and dilation cardiomyopathy (n=3) were included. Segmental LV wall motion (LV-WM) was assessed using a 4-point scale. Wall thickness measurements were calculated in diastolic and systolic short axis images. Two hundred and fifty-two out of 266 (94.7%) normal and 189 out of 214 (88.3%) segments with decreased wall motion were correctly identified by MDCT, yielding a sensitivity of 88% and specificity of 95% for identification of wall motion abnormalities. LV-WM scores were identical in 86.7% of 480 segments (kappa=0.809). MDCT had a tendency to underestimate the degree of wall motion impairment. Interobserver agreement was lower in MDCT (66.5%) than in MRI (89.1%; p<0.01). Normokinetic segments are reliably identified with MDCT. Sensitivity for detection and accurate classification of LV wall motion abnormalities need to be improved. Better temporal resolution of the CT system seems to be the most important factor for enhancing MDCT performance.     

Three-dimensional perfusion imaging of hepatocellular carcinoma using 256-slice multidetector-row computed tomography

Purpose  The aim of this study was to evaluate the clinical capability of three-dimensional (3D) perfusion imaging of hepatocellular carcinoma (HCC) by performing dynamic scanning using a 256-slice multidetector-row CT (MDCT) scanner. Materials and methods  Two patients with HCC were examined in this study. They were scheduled to undergo transcatheter arterial infusion therapy using an arterial infusion reservoir system. The CT system used was a newly developed prototype scanner of 256-slice MDCT. Dynamic CT scanning was performed with intraarterial injection via the reservoir route, and perfusion analysis was done based on the 3D data. Results  The blood flow volume per unit volume in the tumors was significantly increased compared with that in normal hepatic parenchyma. Using a 3D workstation, 3D perfusion images could be displayed by fusing CT images with perfusion images about blood flow volume. Conclusion  Three-dimensional perfusion images, which enable 3D evaluation of perfusion in HCCs, can be generated using 256-slice MDCT.     

The value of computed tomography for predicting empyema-associated malignancy

OBJECTIVE: To determine the value of computed tomography (CT) scanning in detecting associated malignancy in patients with chronic empyema. METHODS: Two radiologists retrospectively reviewed CT scans of 112 consecutive patients with chronic empyema and arrived at a consensus about the findings. Among these patients, 6 were confirmed by pathology evaluation to have empyema-associated malignancy (EAM), including 4 lymphomas. The CT scans were evaluated for the presence of the following findings: a mass in the empyema sac; mass involvement of the extrapleural fat, chest wall, rib, and lung; bulging of the empyema sac; nodular pleural thickening; empyema involvement of the mediastinal pleura; presence of lung nodules (>1 cm); and mediastinal lymph node enlargement. The association between the CT findings and the EAM was analyzed with the Fisher exact test. A multiple logistic regression analysis was used to determine the predictive variables for EAM. Sensitivity, specificity, and positive predictive value were calculated for each finding. RESULTS: All CT findings, except rib involvement and bulging of empyema sac, were significantly associated with EAM (P<0.05). The finding of the presence of a mass, extrapleural fat, and mediastinal involvement showed relatively high sensitivity (100%, 67%, 67%, respectively) and specificity (81%, 87%, 91%, respectively). A bulging of the empyema sac and nodular pleural thickening showed 100% sensitivity, but low specificity (39% and 44%, respectively). Findings from the multiple logistic regression analysis revealed that the presence of a mass and empyema of the mediastinal pleura were significant variables associated with EAM (P<0.05). CONCLUSIONS: Although many CT findings are associated with EAM, most showed either low positive predictive value or low sensitivity. A variety of CT findings should be considered when evaluating CT image-based detection of EAM.     

The value of multidetector-row computed tomography for localization of obscure acute gastrointestinal bleeding

Purpose

There are no simple guidelines on when to perform multidetector-row computed tomography (MDCT) for diagnosis of obscure acute gastrointestinal bleeding (AGIB). We used a risk scoring system to evaluate the diagnostic power of MDCT for patients with obscure AGIB.

Materials and methods

Ninety-two patients with obscure AGIB who were referred for an MDCT scan after unsuccessful endoscopic treatment at presentation were studied. We recorded clinical data and calculated Blatchford score for each patient. Patients who required transfusion more than 500 mL of blood to maintain the vital signs were classified as high-risk patients. Two radiologists independently reviewed and categorized MDCT signs of obscure AGIB. Discordant findings were resolved by consensus. One-way ANOVA was used to compare clinical data between two groups; kappa statistics were used to estimate agreement on MDCT findings between radiologists.

Results

Of the 92 patients, 62 (67.4%) were classified as high-risk patients. Blatchford scores of high-risk patients were significantly greater than those of low-risk patients. Sensitivity for MDCT diagnosing obscure AGIB was 81% in high-risk patients, as compared with 50% in the low-risk. When used in conjunction with selection of the cut-off value of 13 in Blatchford scoring system, the sensitivity and specificity of MDCT were 70.9% and 73.7%, respectively. Contrast extravasation was the most specific sign of AGIB (k = .87), recognition of which would have improved diagnostic accuracy.

Conclusions

With the aid of Blatchford scoring system for evaluating the disease severity, MDCT can localize the bleeders of obscure AGIB more efficiently.     

Technical optimization of four-channel multidetector-row helical computed tomography for depicting arterial stenosis: a phantom study

Purpose: To determine the effects of detector configuration, as well as vessel orientation, on the depiction accuracy of arterial stenosis using four-channel multidetector-row helical computed tomography (MDCT) angiography in vitro.

Material and Methods: Five acrylic vessel phantoms (3 mm in diameter with 25 or 50% stenosis, or 5 mm with 25, 50, or 75% stenosis) were scanned with a four-channel MDCT scanner at five vessel orientations (0, 30, 45, 60, and 90° to the z-axis) using 4×1.25, 2.5, 3.75, and 5.0-mm detector configurations at beam pitches of 0.75 and 1.5. The percentage of stenosis was calculated by the ratio of the full width at half maximum for stenotic and non-stenotic portions of the phantom, and compared to the actual known values.

Results: A detector configuration of 4×1.25 mm provided good reproducibility, as well as high accuracy for assessing vessel stenosis, while a 4×2.5-mm or wider detector configuration caused underestimations of stenosis. Although the phantoms perpendicular to the z-axis were underestimated, the errors were kept in clinically acceptable ranges using the 4×1.25-mm detector configuration.

Conclusion: Four-channel MDCT accurately discerns stenosis for vessel phantoms of 3 or 5 mm in diameter at any orientation when using a detector configuration of 4×1.25 mm.     

Improved diagnosis of hepatic perfusion disorders: value of hepatic arterial phase imaging during helical CT.

The liver has a unique dual blood supply, which makes helical computed tomography (CT) a highly suitable technique for hepatic imaging. Helical CT allows single breath-hold scanning without motion artifacts. Because of rapid image acquisition, two-phase (hepatic arterial phase and portal venous phase) evaluation of the hepatic parenchyma is possible, improving tumor detection and tumor characterization in a single CT study. The arterial and portal venous supplies to the liver are not independent systems. There are several communications between the vessels, including transsinusoidal, transvasal, and transplexal routes. When vascular compromise occurs, there are often changes in the volume of blood flow in individual vessels and even in the direction of blood flow. These perfusion disorders can be detected with helical CT and are generally seen as an area of high attenuation on hepatic arterial phase images that returns to normal on portal venous phase images; this finding reflects increased arterial blood flow and arterioportal shunting in most cases. Familiarity with the helical CT appearances of these perfusion disorders will result in more accurate diagnosis. By recognizing these perfusion disorders, false-positive diagnosis (hypervascular tumors) or overestimation of the size of liver tumors (eg, hepatocellular carcinoma) can be avoided.     

Assessment of major aortopulmonary collateral arteries with multidetector-row computed tomography

Multidetector-row computed tomography (MDCT) studies were performed in three adult patients with pulmonary atresia with a ventricular septal defect. In all patients, the native pulmonary arteries were absent, and the pulmonary circulation was totally supplied by major aortopulmonary collateral arteries (MAPCAs). MDCT studies with 1-mm collimation provided detailed information on MAPCAs and bronchial collaterals, such as the numbers and sites of origin, their varying diameters, their courses, and the areas of the lungs they supply. MDCT studies may provide an efficient road map for safe and successful selective catheterization and may substitute for conventional angiography in patients with considerable risks.     

Diagnostic value of the delayed phase image for iso-attenuating pancreatic carcinomas in the pancreatic parenchymal phase on multidetector computed tomography

Purpose

To assess the value of the delayed phase (DP) in pancreatic carcinomas which appear iso-attenuating in the pancreatic parenchymal phase (PPP).

Materials and methods

Fifty-seven preoperative MDCT studies of pancreatic carcinomas were retrospectively reviewed. The size of the tumors, and the Hounsfield unit (HU) of the tumors and pancreatic parenchyma were measured. The tumor-to-pancreas contrast (TPC: |HU [tumor] − HU [normal pancreas]|) was calculated.

Results

Eight cases (14.0%) showed iso-attenuation and 49 showed hypo-attenuation in the PPP. The DP images revealed seven of eight (87.5%) iso-attenuating tumors to be hyper-attenuating. The size of iso-attenuating tumors was smaller than that of hypo-attenuating tumors (mean ± S.D.: 12.4 ± 4.8 mm vs. 30.3 ± 9.0 mm, p < 0.0001). In hypo-attenuating tumors, TPC in the PPP (60.2 ± 24.6 HU) was higher than those in the portal venous phase (PVP, 40.5 ± 23.0 HU, p < 0.0001) and DP (18.3 ± 11.8 HU, p < 0.0001). In contrast, in iso-attenuating tumors, TPC in the DP (26.0 ± 4.9 HU) was higher than those in the PPP (9.2 ± 3.7 HU, p = 0.0003) and PVP (7.1 ± 4.7 HU, p = 0.001) phases.

Conclusion

The DP image is helpful in depicting small iso-attenuating pancreatic carcinomas as slightly hyper-attenuating tumors.     

Assessment of myocardial infarctions using multidetector-row computed tomography

OBJECTIVE: To evaluate the diagnostic power of contrast-enhanced multidetector-row computed tomography (MDCT) in assessing the presence, age, and size of myocardial infarctions. METHODS: One hundred six patients underwent standard MDCT coronary angiography without additional changes in the protocol. In all patients, a complete patient history and left heart catheterization with biplane contrast ventriculography were available. The MDCT images were reviewed for the presence and age of myocardial infarctions in a blinded fashion. Infarct areas were detected as regions of reduced uptake of contrast in the early arterial phase and/or regional wall thinning. Reviewing the computed tomography (CT) images, CT density values (Hounsfield units [HU]) were measured at the site of infarcted and noninfarcted myocardium, and a volumetric assessment of the infarct size was performed. RESULTS: In 27 of 106 patients, myocardial infarctions were present. Multidetector-row computed tomography detected 23 of 27 infarctions (sensitivity of 85%, specificity of 91%, and accuracy of 90%). Comparing the HU of infarcted versus noninfarcted myocardium, the mean HU of infarcted areas was 54 +/- 19 HU versus 117 +/- 28 HU for noninfarcted myocardium (P < 0.01). Multidetector-row computed tomography was able to differentiate between recent and chronic infarctions. The infarct volumes of recent infarctions (6.3 +/- 3.6 cm) showed a negative correlation to the ejection fraction (EF) according to contrast ventriculography (ie, the larger the infarct volumes as measured using MDCT, the worse was the EF [r = -0.72, P < 0.01]). CONCLUSIONS: Performing standard MDCT coronary angiography, areas of infarcted myocardium can be identified with moderate to high sensitivity, without additional scanning or contrast administration. Infarct localization can be assessed accurately as compared with cineventriculography. To some degree, infarct age and infarct volume can be estimated.     

Eosinophilic hepatic necrosis: magnetic resonance imaging and computed tomography comparison

OBJECTIVE: To compare the findings of magnetic resonance (MR) imaging with those of computed tomography (CT) of focal liver lesions related to peripheral eosinophilia. METHODS: For 12 patients with peripheral eosinophilia (>7%) examined with hepatic MR imaging and CT, 52 focal hepatic lesions larger than 0.5 cm, including 31 lesions simultaneously found on the 2 imaging modalities, were subjected to a comparative analysis of their imaging features. RESULTS: The total number of lesions distinguished from background liver was 39 (75%) on MR imaging and 44 (85%) on CT scans. On arterial phase images of 10 patients with comparable data, homogeneously hyperintense lesions were demonstrated more frequently (P = 0.006) on MR imaging (16 [50%] of 32 lesions) than on CT scans (4 [13%] of 32 lesions). Only 7 (22%) of the 32 hypoattenuating lesions on portal phase CT were depicted as hypointense lesions on portal phase MR images in 12 patients. On delayed phase images in 8 patients, the number of hyperintense lesions on MR images (9 [56%] of 16) was greater (P = 0.077) than that seen on the CT scans (4 [25%] of 16). CONCLUSIONS: For many focal hepatic lesions related to peripheral eosinophilia, dynamic MR imaging more easily demonstrates lesional enhancement on arterial and delayed phases than CT scans. Because of the higher degree of lesional enhancement of MR imaging compared with CT, the lesion-to-liver contrast may not be sufficient to distinguish the lesion from the background liver, resulting in decreased sensitivity of portal phase dynamic MR imaging.     

Radiological assessment of hepatic vein invasion by hepatocellular carcinoma using combined computed tomography hepatic arteriography and computed tomography arterial portography

Purpose

The aim of this study was to elucidate computed tomography hepatic arteriography (CTHA) and CT arterial portography (CTAP) findings characteristic of hepatocellular carcinoma (HCC) with large hepatic venous invasion (HVI) and then to examine whether the presence of minute HVI can be diagnosed based on each finding.

Materials and methods

Combined CTHA and CTAP of 106 HCCs were examined. Two radiologists analyzed the radiological findings of five nodules with large HVI (group vv2). The remaining 101 nodules were classified into two groups: group vv1, positive minute HVI; group vv0, negative HVI. They examined whether each finding observed in group vv2 could be detected in groups vv1 and vv0.

Results

Analysis of group vv2 identified (a) tumor thrombus, (b) early inflow of the contrast into the hepatic vein proximal to the invaded site, and (c) partially decreased portal venous flow in the peripheral parenchyma subject to the involved hepatic vein. Findings (b) and (c) were observed in 16% of group vv1. A significant difference in frequency of finding (c) was obtained between groups vv1 and vv0. The positive and negative predictive values of finding (c) were 66.7% and 77.9%, respectively.

Conclusion

Findings (b) and (c), especially the latter, may partly contribute to the radiological diagnosis of minute HVI.