Gadolinium-enhanced imaging of pediatric thoracic lymphoma: is intravenous contrast really necessary?

OBJECTIVES: Increasing awareness of potential side effects from gadolinium-based contrast agents has underlined the need for contrast-free magnetic resonance imaging (MRI). Numerous recent articles evaluated the risk of potential brain deposits, with the result that research is putting the focus more on alternative unenhanced imaging techniques. The aim of this study was to determine the need for contrast media for chest MRI in primary staging and follow-up care of lymphoma. METHODS: This monocentric, retrospective study encompassed patients under 25 years of age who had undergone histopathological examination of thoracic lymph nodes and at least one chest MRI examination with unenhanced and contrast-enhanced sequences. Seven different thoracic lymph node stations including mediastinal, hilar, periclavicular, and axillary regions were evaluated by two readers regarding lesion diameter, number, shape, necrosis, and infiltration of surrounding structures. Findings were categorized into suspicious (> 1 cm; round; necrosis; infiltration) or non-suspicious. RESULTS: Fifty-one patients (mean age, 16.0 ± 3.7 yrs) with thoracic Hodgkin (70.6%) and non-Hodgkin lymphoma (25.5%) and lymphadenopathy (3.9%) were retrospectively included. Most lymph nodes categorized as suspicious were located in the mediastinal station (86.4%). High agreement (κ = 0.81) between unenhanced and contrast-enhanced sequences was found for both suspicious and non-suspicious lymph nodes. Significant (p < 0.001), but small difference (1 mm) was observed only in sizing mediastinal lymph nodes (all other p > 0.05). No significant difference (smallest p = 0.08) was shown for the use of five different types of contrast media. CONCLUSION: MRI in young patients with thoracic lymphoma can safely be done without the use of contrast agent. KEY POINT: • Thoracic magnetic resonance imaging in young lymphoma patients can safely be done without gadolinium-based contrast agents.

Using coronary CT angiography for guiding invasive coronary angiography: potential role to reduce intraprocedural radiation exposure.

OBJECTIVES: We investigated the potential reduction of patient exposure during invasive coronary angiography (ICA) if the procedure had only been directed to the vessel with at least one ≥ 50% stenosis as described in the CT report. METHODS: Dose reports of 61 patients referred to ICA because of at least one ≥ 50% stenosis on coronary CT angiography (CCTA) were included. Dose-area product (DAP) was documented separately for left (LCA) and right coronary arteries (RCA) by summing up the single DAP for each angiographic projection. The study population was subdivided as follows: coronary intervention of LCA (group 1) or RCA (group 2) only, or of both vessels (group 3), or further bypass grafting (group 4), or no further intervention (group 5). RESULTS: 57.4% of the study population could have benefitted from reduced exposure if catheterization had been directly guided to the vessel of interest as described on CCTA. Mean relative DAP reductions were as follows: group 1 (n = 18), 11.2%; group 2 (n = 2), 40.3%; group 3 (n = 10), 0%; group 4 (n = 3), 0%; group 5 (n = 28), 28.8%. CONCLUSIONS: Directing ICA to the vessel with stenosis as described on CCTA would reduce intraprocedural patient exposure substantially, especially for patients with single-vessel stenosis. KEY POINTS: • Patients with CAD can benefit from decreased radiation exposure during coronary angiography. • ICA should be directed solely to significant stenoses as described on CCTA. • Severely calcified plaques remain a limitation of CCTA leading to unnecessary ICA referrals.

High-pitch dual-source paranasal sinus CT in agitated patients with maxillofacial trauma: analysis of image quality, motion artifacts, and dose aspects.

Background Image quality benefits from high-pitch scanning in agitated patients by reducing acquisition time. Purpose To compare image quality and exposure parameters in patients with maxillofacial trauma on second- and third-generation dual-source computed tomography (DSCT). Material and Methods Four groups were compared. Group 1 was examined on second-generation DSCT (120 kV/50 mAs, pitch 3.0). The other three groups were examined on third-generation DSCT. Group 2 was scanned with 120 kV/50 mAs, pitch 2.2. Automated exposure control (AEC) was used in group 3 and group 4 with pitch factors of 2.2 and 3.0, respectively. Images of third-generation DSCT were reconstructed with iterative reconstruction (IR), of second-generation DSCT with filtered back-projection. CTDIvol, acquisition time, and image quality were compared. Results Thirty patients were included in each group. Average CTDIvol (2.76 ± 0.00 mGy, 2.66 ± 0.00 mGy, 0.74 ± 0.23 mGy, and 0.75 ± 0.17 mGy) was significantly lower on third-generation DSCT with AEC ( P < 0.001). Subjective image quality was rated worst in group 4 due to strong high-pitch artifacts, while in the remaining three groups it was rated good or very good with good inter-observer agreement (k > 0.64). Average acquisition time was significantly shorter with third-generation DSCT (0.47 s, 0.36 s, 0.38 s, 0.30 s; P < 0.001). Conclusion Third-generation DSCT yields faster acquisition times and substantial dose reduction with AEC. A pitch of 2.2 should be preferred, as it results in fewer artifacts. If AEC is used, latest IR ensures that diagnostic image quality is guaranteed.

Influence of contrast material density and kV setting on detectability of calcified plaques on coronary CT angiography.

PURPOSE: To analyze the impact of tube potential and iodine concentration on the visibility of calcified plaques in coronary computed tomography angiography (cCTA). METHODS & MATERIALS: 164 consecutive patients (65.9 % men and a mean age of 57.1 ±â€¯11.3 years) with suspected coronary artery disease underwent calcium scoring (CaSc) scan followed by cCTA with topogram-based automated tube voltage selection (70 kV, 80 kV, 90 kV, 100 kV or 120 kV). In 127 Patients (HC), we injected 50 mL of contrast material (CM) with a concentration of 400 mg iodine per ml and in 37 patients (LC) 50 mL iodine concentration of 280 mg/mL. Sensitivity of cCTA for detecting calcified plaques was calculated with CaSc serving as gold standard. Density of CM enhanced coronary vessels and calcified plaques were quantified by region-of-interest (ROI) measurements in unenhanced and cCTA image series. RESULTS: Overall sensitivity of cCTA to detect calcified plaques was significantly higher using LC compared to HC (79 % vs. 73 %; p = 0.0035). The impact of LC was impressive at 70 kV with an improved sensitivity of 70 % vs. 57.1 % in HC (p = 0.0082). Furthermore, density values of HC enhanced coronary vessels exceeded those of calcified plaques, especially at low kV levels. In LC, except for the 70 kV setting, higher density values were shown for calculi than enhanced vessels. CONCLUSION: Low kV cCTA in routine using highly concentrated CM leads to reduced calcified plaque perceptibility and hence potentially underestimation of stenosis. Thus, low kV cCTA using CM with lower iodine concentration is necessary. In addition, a dose reduction up to 77.7 % can also be benefited.

Comparison of thick- and thin-slice images in thoracoabdominal trauma CT: a retrospective analysis.

PURPOSE: To compare thick (5 mm) and thin slice images (1.5 mm) of lung, soft tissue, and bone window in thoracoabdominal trauma computed tomography. MATERIALS AND METHODS: 167 Patients that underwent thoracoabdominal trauma CT between November 2014 and December 2015 were included in the study. CT data were reconstructed in a transverse direction with 5 mm and 1.5 mm slice images of lung, soft tissue, and bone window. Two blinded raters (radiologists) evaluated the collected data by detecting predefined injuries in different organ areas. Reconstruction and evaluation times as well as detected injuries were noted and compared. RESULTS: Reconstruction and evaluation times were significantly higher with 1.5 mm thin-slice images, and the effect strength according to Rosenthal displayed a strong effect of 0.61 (< 0.1 small effect, 0.3 middle effect, and > 0.5 strong effect). Average evaluation time differences were 62.7 s (33.9 s-91.5 s) in bone window between 1.5 mm and 3 mm for rater 1 (p < 0.001) and 71.4 s (43.1 s-99.7 s) for rater 2 (p < 0.001). Average time differences between 1.5 mm and 5 mm were 68,7 s (43.9 s-93.5 s) for rater 1 and 75.3 s (44.7 s-105.9 s) for rater 2 in lung window (p < 0.001) and 66.6 s (28.8 s-104.4 s) for rater 1 and 114 s (74.4 s-153.6 s) for rater 2 in soft-tissue window (p < 0.001). There was no significant difference regarding soft-tissue and lung injuries, except non-significant improvement in the detection of bone fractures. CONCLUSION: Thin-slice images do not bring any significant benefit in thoracoabdominal trauma CT of soft-tissue and lung injuries, but they can be helpful for the diagnosis of bone fractures and incidental findings.

Improved coronary artery contrast enhancement using noise-optimised virtual monoenergetic imaging from dual-source dual-energy computed tomography.

PURPOSE: To define optimal kiloelectron volt (keV) settings for virtual monoenergetic imaging (VMI) reconstruction at dual-energy coronary computed tomography angiography (DE-CCTA). METHOD: Fifty-one DE-CCTA data sets (33 men; mean age, 63.9 ±â€¯13.2 years) were reconstructed as standard linearly-blended images (F_0.6; 60% of 90 kVp, 40% of 150 kVpSn), and with traditional (VMI) and noise-optimised (VMI+) algorithms from 40 to 100 keV in 10-keV intervals. Objective image quality was assessed with signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements. Three observers subjectively evaluated vascular contrast, image sharpness, noise and delineation of coronary plaques. RESULTS: Median values for objective image analysis were highest in VMI + series at 40 keV (SNR, 44.5; CNR: 33.5), significantly superior (allp < 0.001) to the best VMI series at 70 keV (SNR, 28.1; CNR, 18.4) and standard F_0.6 images (SNR, 23.2; CNR, 15.6). Overall subjective metrics achieved higher scores at 40-keV VMI+ series in comparison to 70-keV VMI series and F_0.6 images (all p < 0.001), with optimal vascular contrast (5; ICC, 0.90), good image sharpness (4; 0.88), low noise (4; 0.82), and optimal plaque delineation (5; 0.89). CONCLUSIONS: DE-CCTA image reconstruction with 40-keV VMI + allows for significant improvement of both objective and subjective image quality.

Indication of whole body computed tomography in pediatric polytrauma patients-Diagnostic potential of the Glasgow Coma Scale, the mechanism of injury and clinical examination.

OBJECTIVE: To evaluate the diagnostic potential of the Glasgow Coma Scale (GCS), the mechanism of injury (MOI) and clinical examination (CE) for the indication of whole body computed tomography (WBCT) in pediatric polytrauma patients. MATERIALS & METHODS: 100 pediatric polytrauma patients with WBCT were analysed in terms of age, gender, (MOI), GCS, detected injury, FAST, CE and Injury Severity Score (ISS). Correlations between all clinical variables and patient groups with (p+) and without (p-) injury were assessed. RESULTS: Mean age was 9.13 ±â€¯4.4 years (28% female patients). Injury was detected in 71% of the patients, most commonly of the head (43%). There was no significant correlation between type or severity of MOI and ISS (p > 0.1). None of the clinical variables had a significant predictive effect on p+. The optimum discrimination threshold of GCS was at 12.5 relating to craniocerebral injuries. Severity of MOI and FAST showed best predictive effects on thoracic and abdominal pathologies, respectively, but with only low sensitivities (<20%). CONCLUSION: There is no clinical variable, which can be used as sole indication for WBCT in pediatric polytrauma patients. GCS had a significant predictive value for craniocerbral injuries and CCT is recommended at GCS ≤ 13.