Thoraco-abdominal high-pitch dual-source CT angiography: experimental evaluation of injection protocols with an anatomical human vascular phantom

Objective

To experimentally evaluate three different contrast injection protocols at thoraco-abdominal high-pitch dual-source computed tomography angiography (CTA), with regard to level and homogeneity of vascular enhancement at different cardiac outputs.

Materials and methods

A uniphasic, a biphasic as well as an individually tailored contrast protocol were tested using a human vascular phantom. Each protocol was scanned at 5 different cardiac outputs (3–5 L/min, steps of 0.5 L/min) using an extracorporeal cardiac pump. Vascular enhancement of the thoraco-abdominal aorta was measured every 5 cm. Overall mean enhancement of each protocol and mean enhancement for each cardiac output within each protocol were calculated. Enhancement homogeneity along the z-axis was evaluated for each cardiac output and protocol.

Results

Overall mean enhancement was significantly higher in the uniphasic than in the other two protocols (all p < .05), whereas the difference between the biphasic and tailored protocol was not significant (p = .76). Mean enhancement among each of the 5 cardiac outputs within each protocol was significantly different (all p < .05). Only within the tailored protocol mean enhancement differed not significantly at cardiac outputs of 3.5 L/min vs. 5 L/min (484 ± 25 HU vs. 476 ± 19 HU, p = .14) and 4 vs. 5 L/min (443 ± 49 HU vs. 476 ± 19 HU, p = .05). Both, uniphasic and tailored protocol yielded homogenous enhancement at all cardiac outputs, whereas the biphasic protocol failed to achieve homogenous enhancement.

Conclusion

This phantom study suggests that diagnostic and homogenous enhancement at thoraco-abdominal high-pitch dual-source CTA is feasible with either a uniphasic or an individually tailored contrast protocol.     

Bolus timing in high-pitch CT angiography of the aorta

Objective

To investigate the bolus geometry in high-pitch CT angiography (CTA) of the aorta without ECG synchronisation in comparison to single-source CT.

Methods

Overall 160 consecutive patients underwent CTA either in conventional single-source mode with a pitch of 1.2 (group 1), or in dual-source mode with a pitch of 3.0 (groups 2, 3 and 4) using different contrast media timings with bolus triggering at 140 HU (5 s, group 1; 10 s, group 2; 12 s, group 3; 14 s, group 4). Contrast material, saline flush, flow rate and kV/mAs settings were kept equal for optimum comparability. Aortic attenuation was measured along the z-axis of the patient at different anatomic landmarks and subjective image quality was compared.

Results

The most homogeneous enhancement of the aorta was reached with a delay of 10 s after reaching the trigger threshold. The imaging length was not significantly different, but the examination time was significantly (p < 0.001) shorter in the high-pitch group (7.7 s vs. 1.7 s for group 1 vs. 2, 3 and 4).

Conclusion

In high-pitch CT angiography using a start delay of 10 s after a trigger threshold of 140 HU in the descending aorta is reached, a homogenous contrast along the z-axis is accomplished.     

Multiphase CT scanning and different intravenous contrast media concentrations in combined F-18-FDG PET/CT: Effect on quantitative and clinical assessment

Purpose

To evaluate the influence of multiphase CT scanning and different intravenous contrast media on contrast enhancement, attenuation correction and image quality in combined PET/CT.

Material and methods

140 patients were prospectively enrolled for F-18-FDG-PET/CT including a low-dose unenhanced, arterial and venous contrast enhanced CT. The first (second) 70 patients, received contrast medium with 370 (300) mg iodine/ml. The iodine delivery rate (1.3 mg/s) and total iodine load (44.4 g) were identical for both groups. Contrast enhancement and maximum and mean standardized FDG uptake values (SUVmax and SUVmean) were determined for the un-enhanced, arterial and venous PET/CT at multiple anatomic sites and PET reconstructions were visually evaluated.

Results

Arterial contrast enhancement was significantly higher for the 300 mg/ml contrast medium compared to 370 mg I/ml at all anatomic sites. Venous enhancement was not different between the two contrast media. SUVmean and SUVmax were significantly higher for the contrast enhanced compared to the non-enhanced PET/CT at all anatomic sites (all P < 0.001). Tracer uptake was significantly higher in the arterial than in the venous PET/CT in the arteries using both contrast media (all P < 0.001). No differences in tracer uptake were found between the contrast media (all P > 0.05). Visual assessment revealed no relevant differences between the different PET reconstructions.

Conclusions

There is no relevant qualitative influence on the PET scan from the use of different intravenous contrast media in its various phases in combined multiphase PET/CT. For quantitative analysis of tracer uptake it is required to use an identical PET/CT protocol.     

Dual-energy CT angiography of the lungs: Comparison of test bolus and bolus tracking techniques for the determination of scan delay

Objective

To prospectively compare test bolus and bolus tracking for the determination of scan delay of pulmonary dual-energy CT angiography in patients with suspected pulmonary embolism.

Materials and methods

60 consecutive patients referred for CTA for exclusion of PE were randomized either into a test bolus group or into a bolus tracking group. All exams were performed on a 64-channel dual source CT scanner. A standard single-acquisition dual-energy CTA was performed after injection of 100 ml Iomeprol 400 followed by a saline chaser of 4 ml/s. The scan delay was determined using either test bolus (n = 30) or bolus tracking (n = 30). Test bolus was performed using an additional 20 ml Iomeprol 400 injected with a rate of 4 ml/s during acquisition of a series of dynamic low-dose monitoring scans followed by injection of a saline bolus of 20 ml using the same flow rate. For DECT angiography of the lungs 100 ml Iomeprol 400 was injected with an injection rate of 4 ml/s followed by a saline chaser of 20 ml using the same flow rate. Attenuation profiles of different vascular segments (pulmonary arteries, pulmonary parenchyma, aorta, all 4 heart chambers) were measured to evaluate the timing techniques. Overall image quality of dual-energy “perfusion” maps and virtual 120 kV CTA images was evaluated by two radiologists regarding the present of artifacts.

Results

In all patients an adequate and homogeneous contrast enhancement of more than 400 Hounsfield units (HU) was achieved in the different vascular districts. No statistically significant difference between test bolus and bolus tracking was found regarding vessel attenuation or overall image quality.

Conclusion

A homogeneous opacification of the different vascular territories and the pulmonary parenchyma as well as a sufficient image quality can be achieved with either bolus tracking or test bolus techniques.     

Multiphase contrast-saline mixture injection with dual-flow in 64-row MDCT coronary CTA

Purpose

To explore the feasibility of multiphase contrast–saline mixture with dual-flow injection technique for visualization of right ventricular (RV) cavity and interventricular septum (IVS) in 64-row multidetector computed tomography (MDCT) coronary angiography.

Materials and methods

Twenty-four patients underwent coronary CT angiography (CTA) imaging with 64-row MDCT. In twelve patients (group A), 60 ml contrast medium (CM) bolus was followed by 40 ml saline, and in the other twelve patients (group B), 50 ml CM bolus was followed by 50 ml contrast–saline mixture at 60:40 ratio. The CM, saline and contrast–saline mixture flow rate were all 5.0 ml/s. Two experienced radiologists measured the CT values of ascending aorta, descending aorta, pulmonary artery and RV, rated the uniformity of RV cavity, the visualization of coronary arteries and IVS independently.

Results

By Kappa test, agreement between the two radiologists was 0.93 and 0.86 concerning the CT value measurements and the grades of the three indexes, respectively. By t-test, the mean CT values of ascending aorta and descending aorta of the two groups had no statistical difference (t = 1.459, P > 0.05; t = 1.619, P > 0.05); while the mean CT values of pulmonary artery and RV cavity had statistical differences (t = 8.316, P < 0.05; t = 10.372, P < 0.05). By two-related rank sum test, according to the visualization of coronary arteries and the uniformity of RV cavity, there were no statistical differences (U = 66.00, P > 0.05; U = 54.00, P > 0.05); while according to the visualization of IVS, group B was better than group A (U = 8.00, P < 0.05).

Conclusion

In coronary CTA, a contrast–saline mixture after CM bolus can provide clear visualization of RV and IVS and LV without impairing coronary CTA image.     

Estimation and comparison of effective dose (E) in standard chest CT by organ dose measurements and dose-length-product methods and assessment of the influence of CT tube potential (energy dependency) on effective dose in a dual-source CT

Purpose

To determine effective dose (E) during standard chest CT using an organ dose-based and a dose-length-product-based (DLP) approach for four different scan protocols including high-pitch and dual-energy in a dual-source CT scanner of the second generation.

Materials and methods

Organ doses were measured with thermo luminescence dosimeters (TLD) in an anthropomorphic male adult phantom. Further, DLP-based dose estimates were performed by using the standard 0.014 mSv/mGycm conversion coefficient k. Examinations were performed on a dual-source CT system (Somatom Definition Flash, Siemens). Four scan protocols were investigated: (1) single-source 120 kV, (2) single-source 100 kV, (3) high-pitch 120 kV, and (4) dual-energy with 100/Sn140 kV with equivalent CTDIvol and no automated tube current modulation. E was then determined following recommendations of ICRP publication 103 and 60 and specific k values were derived.

Results

DLP-based estimates differed by 4.5–16.56% and 5.2–15.8% relatively to ICRP 60 and 103, respectively. The derived k factors calculated from TLD measurements were 0.0148, 0.015, 0.0166, and 0.0148 for protocol 1, 2, 3 and 4, respectively. Effective dose estimations by ICRP 103 and 60 for single-energy and dual-energy protocols show a difference of less than 0.04 mSv.

Conclusion

Estimates of E based on DLP work equally well for single-energy, high-pitch and dual-energy CT examinations. The tube potential definitely affects effective dose in a substantial way. Effective dose estimations by ICRP 103 and 60 for both single-energy and dual-energy examinations differ not more than 0.04 mSv.     

Contrast timing in computed tomography: effect of different contrast media concentrations on bolus geometry

Objective

To assess the effect of low-osmolar, monomeric contrast media with different iodine concentrations on bolus shape in aortic CT angiography.

Materials and methods

Repeated sequential computed tomography scanning of the descending aorta of eight beagle dogs (5 male, 12.7 ± 3.1 kg) was performed without table movement with a standardized CT scan protocol. Iopromide 300 (300 mg I/mL), iopromide 370 (370 mg I/mL) and iomeprol 400 (400 mg I/mL) were administered via a foreleg vein with an identical iodine delivery rate of 1.2 g I/s and a total iodine dose of 300 mg I/kg body weight. Time-enhancement curves were computed and analyzed.

Results

Iopromide 300 showed the highest peak enhancement (445.2 ± 89.1 HU), steepest up-slope (104.2 ± 17.5 HU/s) and smallest full width at half maximum (FWHM; 5.8 ± 1.0 s). Peak enhancement, duration of FWHM, enhancement at FWHM and up-slope differed significantly between iopromide 300 and iomeprol 400 (p < 0.05). Except for enhancement at FWHM there were no significant differences between iopromide 300 and iopromide 370 and iopromide 370 and iomeprol 400 (p > 0.05).

Conclusions

Low viscous iopromide 300 results in a better defined bolus with a significantly higher peak enhancement, steeper up-slope and smaller FWHM when compared to iomeprol 400. These characteristics potentially affect contrast timing.     

Diagnostic image quality of a comprehensive high-pitch dual-spiral cardiothoracic CT protocol in patients with undifferentiated acute chest pain

Objective

To evaluate diagnostic image quality of high-pitch dual source comprehensive cardiothoracic CT protocol in patients presenting with acute undifferentiated chest pain.

Materials and methods

Consecutive symptomatic subjects (n = 51) with undifferentiated acute chest pain underwent ECG-synchronized high-pitch dual-spiral chest CT angiography (Definition Flash, Siemens Medical Solutions, 2 × 100 kVp or 2 × 120 kV if BMI > 30, collimation: 128 × 0.6 mm, pitch: 3.2). Independent investigators determined the image quality of each cardiac and pulmonary vessel segment, measured contrast-to-noise-ratio (CNR), and determined radiation exposure. In addition, the prevalence of CT findings (pulmonary embolism (PE), aortic dissection (AD) and significant coronary stenosis (≥50%)) was determined. Univariate and multivariate analysis were performed to determine the subpopulation with highest diagnostic quality.

Results

Among 51 subjects (66% male, average age: 63 ± 15.8), the prevalence of positive CT findings was moderate (overall: 11.7%). Overall, image quality of the pulmonary, aortic and coronary vasculature was good (1.26 ± 0.43 and CNR: 2.52) with an average radiation dose of 3.82 mSv and 3.2% of segments rated non-evaluable. The image quality was lowest in the coronary arteries (p = 0.02), depending on the heart rate (r = 0.52, p < 0.001). In subjects with a heart rate of ≤65 bpm (n = 30) subjective image quality and CNR of the coronary arteries were higher (1.6 ± 0.5 vs. 2.1 ± 0.5, p = 0.03 and 1.21 ± 0.3 vs. 1.02 ± 0.3, p = 0.05) with only 1.5% segments classified as non-evaluable.

Conclusion

High-pitch dual-spiral comprehensive cardiothoracic CT provides low radiation exposure with excellent image quality at heart rates ≤65 bpm. In subjects with higher heart rates, image quality of the aortic and pulmonary vasculature remains excellent, while the assessment of the coronary arteries degrades substantially.     

Routine chest and abdominal high-pitch CT: an alternative low dose protocol with preserved image quality

Objective

To investigate the radiation dose and image quality of the high-pitch dual source computer tomography (DSCT) for routine chest and abdominal scans.

Methods

130 consecutive patients (62 female, 68 male, median age 55 years) were included. All patients underwent 128-slice high-pitch DSCT (chest n = 99; abdomen n = 84) at a pitch of 3.2. Two observers independently rated image quality using a 4-point score (1: excellent to 4: non-diagnostic). Image noise was measured and operational radiation dose quantities were recorded. An additional group of 132 patients (chest, n = 80; abdomen n = 52) scanned with standard-pitch CT matched for age, gender, and body mass index (BMI) served as control group.

Results

Interobserver agreement for image quality rating was good (k = 0.74). Subjective image quality of high-pitch CT was diagnostic in all patients (median score chest; 2, median score abdomen: 2). Image noise of high-pitch CT was comparable to standard-pitch for the chest (p = 0.32) but increased in the abdomen (p < 0.0001). For high-pitch CT radiation dose was 4.4 ± 0.9 mSv (chest) and 6.5 ± 1.2 mSv (abdomen). These values were significantly lower compared to standard-pitch CT (chest: 5.5 ± 1.2 mSv; abdomen: 11.3 ± 3.8 mSv).

Conclusion

Based on the technical background high-pitch dual source CT may serve as an alternative scan mode for low radiation dose routine chest and abdominal CT.     

Influence of hemodynamic parameters on coronary artery attenuation with 320-detector coronary CT angiography

Objectives

To investigate the relationship between cardiac output, end diastolic volume and the contrast enhancement in coronary CT angiography using 320-detector CT.

Materials and methods

A total of 38 patients underwent coronary CT angiography by using a 320-detector CT scanner (detector configuration, 320 × 0.5 mm). The attenuation value of the ascending aorta at the level of the orifice of the left main trunk was measured. The cardiac output (CO), end diastolic volume (EDV) and stroke volume (SV) were measured by echocardiography. The EDV was normalized to the body surface area (BSA). The total blood volume injected from the left ventricle from the beginning of the contrast agent injection to the time of image acquisition was determined to be the total injected blood volume (TIV), which is a product of SV and the number of heart beats from the initiation of contrast agent injection to the scan.

Results

There was a negative correlation between the attenuation of the ascending aorta and CO (r = −0.44, P = 0.0053). However, the negative correlation between the attenuation of the ascending aorta and TIV was stronger (r = −0.52, P = 0.0007). There was a negative correlation between the attenuation of the ascending aorta and EDV/BSA (r = −0.45, P = 0.0039).

Conclusion

In 320-detector CT, contrast enhancement in CCTA with a lesser amount of contrast medium decreases when cardiac output is high. Patients with larger EDV/BSA may also show decreased attenuation.     

Feasibility of a fixed scan delay technique using a previous bolus tracking technique data for dynamic hepatic CT

Objective

To compare the quality of contrast enhancement and hepatic CT images acquired using bolus tracking technique at two different time points and those acquired with fixed scan delay technique using a previous bolus tracking data.

Materials and methods

Fifty patients who underwent 3 different hepatic CT exams (25-s fixed injection of 600 mg iodine (I)/kg or 100 mL of 370 mg I/mL nonionic contrast medium) were enrolled. The first and second exams were performed with a bolus tracking technique. The third exam was performed with a fixed scan delay technique using the first exam data. Differences in attenuation values in the abdominal organs were examined and evaluated visually on hepatic arterial phase images.

Results

There was no significant difference in the mean 50-HU threshold times between the first and second bolus tracking exams with intra-patient differences between them (1.3 ± 0.9 s). No significant intra-patient differences were noted in organ attenuation and visual evaluation on hepatic arterial phase images between the 3 exams.

Conclusion

The fixed scan delay technique using a previous bolus tracking data is feasible for hepatic CT exams to follow up hepatocellular carcinoma.     

Cost reduction in abdominal CT by weight-adjusted dose

Aim

To analyze the influence of contrast dose adjusted by weight vs. fixed contrast dose in the attenuation and cost of abdominal computed tomography (CT).

Materials and methods

A randomised, consecutive, parallel group study was conducted in 151 patients (74 men and 77 women, age range 22–67 years), studied with the same CT helical protocol. A dose at 1.75 ml/kg was administered in 101 patients while 50 patients had a fixed dose of 120 ml of same non-ionic contrast material (320 mg/ml). Mean enhancements were measured at right hepatic lobe, superior abdominal aorta and inferior cava vein. Statistical analysis was weight-stratified (<60, 61–70, 71–80 and >81 kg).

Results

Aortic attenuation was significantly superior (p < 0.05) in the dose adjusted by weight group than in the fixed dose group. Patients who weighed >61 kg in dose-adjusted group, presented higher hepatic attenuation, being statistically significant in those >81 kg (p < 0.01). In dose-adjusted group, there was a savings of €4.1 per patient in patients weighing <80 kg. In patients weighing >80 kg, there was an over cost of €10.7 per patient.

Conclusions

An injection volume of 1.75 ml/kg offers an optimal diagnostic quality with a global savings of €1.34 per patient.     

X-ray induced DNA double-strand breaks in coronary CT angiography: comparison of sequential, low-pitch helical and high-pitch helical data acquisition

Background

Aim of this study was to compare DNA double-strand breaks (DSBs) in blood lymphocytes of patients undergoing high-pitch helical, low-pitch helical and sequential coronary CT angiography.

Methods and results

66 patients were examined with various scan protocols and modes (low-pitch helical scan: 100–120 kV, 320–438 mAs/rot, pitch 0.18–0.39, with or without ECG-pulsing, n = 35; prospectively ECG-triggered high-pitch helical scan: 100–120 kV, 320–456 mAs/rotation, pitch 3.2–3.4, n = 19; prospectively ECG-triggered sequential scan: 100–120 kV, 150–300 mAs or 320–370 mAs/rotation, n = 12) either using a 64-slice or 128-slice dual-source CT or a 128-slice single source CT scanner. Blood samples were obtained before and 30 min after CT and DSBs were analyzed in isolated lymphocytes using γ-H2AX immunofluorescence microscopy.A significant increase of DSBs was measurable 30 min after CTA (range 0.01–0.71/cell). CT induced DSBs showed a significant correlation with the estimated effective dose (ρ = 0.90, p < 0.00001). Both prospectively ECG-triggered sequential (0.10 DSBs/cell, 176 mGy cm, p < 0.00001) and high-pitch helical scan protocols (0.03 DSBs/cell, 109 mGy cm, p < 0.00001) led to a significant reduction of median DLP and DSB levels compared to low-pitch helical scans (0.34 DSBs/cell, 828 mGy cm). A reduction of the tube voltage resulted in significantly lower whereas additional calcium scoring resulted in elevated DLP and DNA damages (p < 0.05 each).

Conclusion

In coronary CTA, data acquisition protocols have a significant influence on the X-ray induced DSB levels. Using γ-H2AX immunofluorescence microscopy different scan modes in different CT generations can be compared concerning their biological impact.     

Time-resolved CT angiography in aortic dissection

Objectives

We performed this study to assess feasibility and additional diagnostic value of time-resolved CT angiography of the entire aorta in patients with aortic dissection.

Materials and methods

14 consecutive patients with known or suspected aortic dissection (aged 60 ± 9 years) referred for aortic CT angiography were scanned on a dual-source CT scanner (Somatom Definition Flash; Siemens, Forchheim, Germany) using a shuttle mode for multiphasic image acquisition (range 48 cm, time resolution 6 s, 6 phases, 100 kV, 110 mAs/rot). Effective radiation doses were calculated from recorded dose length products. For all phases, CT densities were measured in the aortic lumen and renal parenchyma. From the multiphasic data, 3 phases corresponding to a triphasic standard CT protocol, served as a reference and were compared against findings from the time-resolved datasets.

Results

Mean effective radiation dose was 27.7 ± 3.5 mSv. CT density of the true lumen peaked at 355 ± 53 HU. Compared to the simulated triphasic protocol, time-resolved CT angiography added diagnostic information regarding a number of important findings: the enhancement delay between true and false lumen (n = 14); the degree of membrane oscillation (n = 14); the perfusion delay in arteries originating from the false lumen (n = 9). Other additional information included true lumen collapse (n = 4), quantitative assessment of renal perfusion asymmetry (n = 2), and dynamic occlusion of aortic branches (n = 2). In 3/14 patients (21%), these additional findings of the multiphasic protocol altered patient management.

Conclusions

Multiphasic, time-resolved CT angiography covering the entire aorta is feasible at a reasonable effective radiation dose and adds significant diagnostic information with therapeutic consequences in patients with aortic dissection.     

Low contrast volume run-off CT angiography with optimized scan time based on double-level test bolus technique – feasibility study

Purpose

To verify the technical feasibility of low contrast volume (40 mL) run-off CT angiography (run-off CTA) with the individual scan time optimization based on double-level test bolus technique.

Materials and methods

A prospective study of 92 consecutive patients who underwent run-off CTA performed with 40 mL of contrast medium (injection rate of 6 mL/s) and optimized scan times on a second generation of dual-source CT. Individual optimized scan times were calculated from aortopopliteal transit times obtained on the basis of double-level test bolus technique – the single injection of 10 mL test bolus and dynamic acquisitions in two levels (abdominal aorta and popliteal arteries). Intraluminal attenuation (HU) was measured in 6 levels (aorta, iliac, femoral and popliteal arteries, middle and distal lower-legs) and subjective quality (3-point score) was assessed. Relations of image quality, test bolus parameters and arterial circulation involvement were analyzed.

Results

High mean attenuation (HU) values (468; 437; 442; 440; 342; 274) and quality score in all monitored levels was achieved. In 91 patients (0.99) the sufficient diagnostic quality (score 1–2) in aorta, iliac and femoral arteries was determined. A total of 6 patients (0.07) were not evaluable in distal lower-legs. Only the weak indirect correlation of image quality and test-bolus parameters was proved in iliac, femoral and popliteal levels (r values: −0.263, −0.298 and −0.254). The statistically significant difference of the test-bolus parameters and image quality was proved in patients with occlusive and aneurysmal disease.

Conclusion

We proved the technical feasibility and sufficient quality of run-off CTA with low volume of contrast medium and optimized scan time according to aortopopliteal transit time calculated from double-level test bolus.     

Evaluation of contrast medium enhancement and [(18)F]-FDG uptake of liver metastasis in PET/CT prior to therapy

Objective

To evaluate the contrast medium enhancement and [¹⁸F]-FDG uptake of liver metastases in patients suffering from colon or breast carcinoma prior to therapy.

Material and methods

PET/CT (Philips Gemini) with 200 MBq [¹⁸F]-FDG and contrast medium was performed in 50 patients with colon and 39 patients with breast carcinoma. Lesions were characterized with the presence or the absence of a rim enhancement. The area size, the HU_mean, HU_max, SUV_mean, SUV_max of the lesion and of the liver were determined. The standard uptake values (SUVs) were correlated with the tumor markers CEA and CA 15-3.

Results

The lesions of colon carcinoma had HU_mean-values of 70.7 ± 19.2 and of breast carcinoma 88.1 ± 21.7 (p < 0.0001). In breast cancer the SUV_mean was 3.9 ± 1.3 versus 4.4 ± 1.9 in colon carcinoma (p = 0.0182). Lesion of colon carcinoma with rim enhancement had a significantly higher SUV_mean (4.4 ± 1.5 versus 3.6 ± 1.2; p = 0.001) and SUV_max (6.7 ± 2.6 versus 5.1 ± 2.1; p = 0.000) than lesions without a rim enhancement. A good correlation between tumor markers and SUVs_max could be found in both tumor groups; r = 0.83 (p < 0.01) for colon carcinoma and r = 0.82 (p < 0.01) for breast carcinoma.

Conclusions

The rim enhancement of the lesions in colon carcinoma indicate a significantly higher SUV.     

Primary adrenal lymphoma: radiological; pathological, clinical correlation

Objective

The purpose of this study was to analyze CT and MR imaging (MRI) manifestation of primary adrenal lymphoma in order to better understand of this rare disease.

Materials and methods

Six patients (4 men, 2 women; median age, 65.5 years) with pathologically proven primary adrenal lymphoma were retrospectively reviewed. Imaging findings (CT&;MRI, n = 3; only CT, n = 3) were analyzed and correlated with clinical and pathologic findings.

Results

All cases were pathologically proven primary adrenal diffuse large B-cell lymphoma with bilateral lesions in 3 cases respectively. Maximum diameters of the 9 lesions were 6.1–14.8 cm, median 10.5 cm. Seven lesions were round, oval or oblong, and 2 lesions irregular. Seven lesions were well-defined and 2 had ill-defined margins. Unenhanced CT density of 9 lesions and MR signal intensity of T1 weighted images of 6 lesions were similar to that of muscle, and all 6 lesions were hyperintense on T2-weighted MR images. Following intravenous injection of contrast media, 6 lesions had mild enhancement and 3 lesions had moderate enhancement on parenchymal phase imaging. Enhancement was homogenous in three, slightly inhomogeneous in four, and heterogeneous in two. Seven lesions, in 5 cases, infiltrated the adjacent tissues or organs in patients with large tumors.

Conclusion

Primary adrenal lymphoma usually manifests as large, well-defined, soft-tissue masses replacing the adrenal gland with homogeneous or slightly inhomogeneous enhancement. Large tumors especially tend to infiltrate adjacent structures.     

Quantification of left and right ventricular function and myocardial mass: comparison of low-radiation dose 2nd generation dual-source CT and cardiac MRI

Objective

To prospectively evaluate the accuracy of left and right ventricular function and myocardial mass measurements based on a dual-step, low radiation dose protocol with prospectively ECG-triggered 2nd generation dual-source CT (DSCT), using cardiac MRI (cMRI) as the reference standard.

Materials and methods

Twenty patients underwent 1.5 T cMRI and prospectively ECG-triggered dual-step pulsing cardiac DSCT. This image acquisition mode performs low-radiation (20% tube current) imaging over the majority of the cardiac cycle and applies full radiation only during a single adjustable phase. Full-radiation-phase images were used to assess cardiac morphology, while low-radiation-phase images were used to measure left and right ventricular function and mass. Quantitative CT measurements based on contiguous multiphase short-axis reconstructions from the axial CT data were compared with short-axis SSFP cardiac cine MRI. Contours were manually traced around the ventricular borders for calculation of left and right ventricular end-diastolic volume, end-systolic volume, stroke volume, ejection fraction and myocardial mass for both modalities. Statistical methods included independent t-tests, the Mann–Whitney U test, Pearson correlation statistics, and Bland–Altman analysis.

Results

All CT measurements of left and right ventricular function and mass correlated well with those from cMRI: for left/right end-diastolic volume r = 0.885/0.801, left/right end-systolic volume r = 0.947/0.879, left/right stroke volume r = 0.620/0.697, left/right ejection fraction r = 0.869/0.751, and left/right myocardial mass r = 0.959/0.702. Mean radiation dose was 6.2 ± 1.8 mSv.

Conclusions

Prospectively ECG-triggered, dual-step pulsing cardiac DSCT accurately quantifies left and right ventricular function and myocardial mass in comparison with cMRI with substantially lower radiation exposure than reported for traditional retrospective ECG-gating.     

Scirrhous hepatocellular carcinoma: comparison with usual hepatocellular carcinoma based on CT-pathologic features and long-term results after curative resection

Objective

To compare the CT and pathologic features and the long-term results of scirrhous hepatocellular carcinoma (HCC) after a curative resection with those of usual HCC.

Methods

Twenty-one patients with a scirrhous HCC and 296 patients with a usual HCC underwent contrast-enhanced triple-phase helical CT examinations before and after the curative resection. The CT and pathological features of scirrhous HCC, along with the cumulative survival and recurrence rates after the curative resection using a Kaplan–Meier method were compared with those of a usual HCC.

Results

The common CT features of scirrhous HCC were an ill-defined tumor margin (76%), peripheral rim-like enhancement on arterial and portal phases (62%), presence of area of prolonged and delayed enhancement on equilibrium phase (95%), and hepatic surface retraction (59%) and the uncommon CT features were presence of washout area (19%) and tumor capsule enhancement (5%), which were significantly different from those of usual HCC (p < 0.05). Pathologically, the tumor capsule formation (29%) and tumor necrosis or hemorrhage (10%) were significantly less than those (81% and 43%, respectively) in usual HCC (p < 0.05), while portal or hepatic vein involvement (33%) was significantly more common than in usual HCC (9%) (p < 0.05). There were no statistically significant differences in the 5-year cumulative survival and recurrence rates between the two groups (p > 0.05).

Conclusion

Scirrhous HCC showed distinct CT and pathologic features from those of usual HCC. After the curative resection, the long-term results of scirrhous and usual HCCs were not significantly different.     

Prospectively ECG gated CT pulmonary angiography versus helical ungated CT pulmonary angiography: impact on cardiac related motion artifacts and patient radiation dose

Objective

To compare prospectively ECG gated CT pulmonary angiography (CTPA) with routine helical ungated CTPA for cardiac related motion artifacts and patient radiation dose.

Subjects and methods

Twenty patients with signs and symptoms suspicious for pulmonary embolism and who had a heart rate below 85 were scanned with prospectively ECG gated CTPA. These gated exams were matched for several clinical parameters to exams from twenty similar clinical patients scanned with routine ungated helical CTPA. Three blinded independent reviewers subjectively evaluated all exams for overall pulmonary artery enhancement and for several cardiac motion related artifacts, including vessel blurring, intravascular shading, and double line. Reviewers also measured pulmonary artery intravascular density and image noise. Patient radiation dose for each technique was compared. Fourteen clinical prospectively ECG gated CTPA exams from a second institution were evaluated for the same parameters.

Results

Prospectively ECG gated CTPA resulted in significantly decreased motion-related image artifact scores in lung segments adjacent to the heart compared to ungated CTPA. Measured image noise was not significantly different between the two types of CTPA exams. Effective dose was 28% less for prospectively ECG gated CTPA (4.9 mSv versus 6.8 mSv, p = 0.02). Similar results were found in the prospectively ECG gated exams from the second institution.

Conclusion

Compared to routine helical ungated CTPA, prospectively ECG gated CTPA may result in less cardiac related motion artifact in lung segments adjacent to the heart and significantly less patient radiation dose.