Kardiale Niedrigdosis-Computertomographie

Cardiac CT has evolved to a robust and accurate imaging modality in the cardiac diagnostic armamentarium. However, technical developments had been accompanied with an overall increase in radiation exposure. In the last years, several technical developments and algorithms aimed at the reduction of radiation exposure in cardiac CT. The most relevant dose reduction strategies will be highlighted in this article including appropriate indications for cardiac CT, different ECG synchronization techniques, reduction of tube voltage, and high-pitch CT studies

Size, shape and age-related changes of the mandibular condyle during childhood

Objective: To determine age-related differences in the size and shape of the mandibular condyle in children to establish anatomical reference values. Methods: A total of 420 mandibular condyles in 210 children (mean age, 7years) were retrospectively analysed by using computed tomography (CT) imaging. The greatest left-right (LRD) and anterior-posterior (APD) diameters and the anteversion angles (AA) were measured by two readers. An APD/LRD ratio was calculated. The shape of the condyles was graded into three types on sagittal images. Correlations of parameters with the children's age were assessed by using Pearson's correlation analyses. Results: The LRD (mean, 14.1 ± 2.4mm), APD (mean, 7.3 ± 1.0mm) and LRD/APD ratio (mean, 1.9 ± 0.3) increased (r LRD = 0.70, p < 0.01; r APD = 0.56, p < 0.01; r rat = 0.28, p < 0.01) while the AA (mean, 27 ± 7°) decreased significantly (r antang = −0.26, p < 0.001) with age. The condylar shape as determined on sagittal images correlated significantly with age (r = 0.69, p < 0.05). Boys had significantly higher anteversion angles (p < 0.01), greater LRDs (p < 0.05) and greater mean ratios (p < 0.05). Conclusion: The mandibular condyle is subject to significant age-related changes in size and shape during childhood. As the size of the condyles increases with age, the anteversion angles decrease and the shape of the condyle turns from round to ova

Whole-body CT in polytrauma patients: effect of arm positioning on thoracic and abdominal image quality

The purpose of this study is to assess the influence of different arm positioning techniques on thoracic and abdominal image quality and radiation dose of whole-body trauma CT (wbCT). One hundred and fifty polytrauma patients (104 male, mean age 47 ± 19) underwent wbCT with arms elevated above the head (group A, n = 50), alongside the abdomen (group B, n = 50), and on a pillow ventrally to the chest with both arms flexed (group C, n = 50). Two blinded, independent observers measured image noise and rated image quality (scores 1-3) of the liver, aorta, spleen, spine, and lower lungs. Radiation dose parameters were noted, and the abdomens' anterior-posterior diameter and scan lengths were measured. Interreader agreements for image noise (r = 0.86; p < 0.001) and subjective image quality (k = 0.71-0.84) were good. Noise was lower (p < 0.05), image quality of the liver, aorta, spleen, and spine was higher, and radiation dose lower in group A than in groups B and C (p < 0.001, each). Image quality of the spleen, liver, and aorta were higher in group C than in group B (p < 0.05, each). No significant differences in scan length (p = 0.61) were found among groups. Abdominal anterior-posterior diameter correlated significantly with noise (r = 0.82; p < 0.01) and dose (r = 0.47; p < 0.001). Estimated effective radiation doses were significantly (p < 0.001) higher in groups B (21.2mSv) and C (21.9mSv) as compared to A (16.1mSv). In wbCT for polytrauma patients, positioning of the arms above the head results in better image quality and lower radiation dose. Placing the flexed arms on a large pillow ventrally to the chest significantly improves image quality as compared to positioning alongside the abdome

Synovitis maps for the assessment of inflammatory diseases of the hand

Objectives: To compare accuracy and review times of FLASH-MRI-derived synovitis maps (SM) with conventional MR images (cMRI) in the assessment of articular synovitis and tenosynovitis of the hand. Methods: 80 hands in 40 patients (mean age, 48years; range, 15-72years) were assessed for synovitis on cMRI and SM by two readers independently. Reporting times and diagnostic confidence (scale: 1 = least, 5 = most confident) were measured. Results from an assessment of a panel of senior musculoskeletal radiologists served as the standard of reference. Results: Sensitivity and specificity for the detection of articular synovitis were 0.91/1.00 (R1) and 1.00/0.67 (R2) on cMRI and 0.87/0.75 (R1) and 0.91/0.45 (R2) on SM and for the detection of tenosynovitis 0.95/0.63 (R1) and 0.67/0.79 (R2) on cMRI and 0.67/0.89 (R1) and 0.38/1.00 (R2) on SM. Mean review times (cMRI/SM, sec) were 142/37 (R1) and 167/25 (R2). Mean diagnostic confidence (cMRI/SM) was 3.7/3.4 (R1) and 3.2/3.5 (R2) for articular synovitis and 4.0/4.0 (R1), 3.3/3.7 (R2) for tenosynovitis. Conclusion: Synovitis maps provide a comparable diagnostic accuracy to conventional MR images in the assessment of articular synovitis and tenosynovitis of the hand. Because of short review times, synovitis maps provide a fast overview of locations with synovial enhancemen

Low-dose CT of the lung: potential value of iterative reconstructions

Objectives: To prospectively assess the impact of sinogram-affirmed iterative reconstruction (SAFIRE) on image quality of nonenhanced low-dose lung CT as compared to filtered back projection (FBP). Methods: Nonenhanced low-dose chest CT (tube current-time product: 30mAs) was performed on 30 patients at 100kVp and on 30 patients at 80kVp. Images were reconstructed with FBP and SAFIRE. Two blinded, independent readers measured image noise; two readers assessed image quality of normal anatomic lung structures on a five-point scale. Radiation dose parameters were recorded. Results: Image noise in datasets reconstructed with FBP (57.4 ± 15.9) was significantly higher than with SAFIRE (31.7 ± 9.8, P < 0.001). Image quality was significantly superior with SAFIRE than with FBP (P < 0.01), without significant difference between FBP at 100kVp and SAFIRE at 80kVp (P = 0.68). Diagnostic image quality was present with FBP in 96% of images at 100kVp and 88% at 80kVp, and with SAFIRE in 100% at 100kVp and 98% at 80kVp. There were significantly more datasets with diagnostic image quality with SAFIRE than with FBP (P < 0.01). Mean CTDIvol and effective doses were 1.5 ± 0.7mGy·cm and 0.7 ± 0.2mSv at 100kVp, and 1.4 ± 2.8mGy·cm and 0.5 ± 0.2mSv at 80kVp (P < 0.001, both). Conclusions: Use of SAFIRE in low-dose lung CT reduces noise, improves image quality, and renders more studies diagnostic as compared to FBP. Key Points : • Low-dose computed tomography is an important thoracic investigation tool. • Radiation dose can be less than 1mSv with iterative reconstructions. • Iterative reconstructions render more low-dose lung CTs diagnostic compared to conventional reconstruction

Triple rule-out CT in the emergency department: protocols and spectrum of imaging findings

Triage decisions in patients suffering from acute chest pain remain a challenge. The patient's history, initial cardiac enzyme levels, or initial electrocardiograms (ECG) often do not allow selecting the patients in whom further tests are needed. Numerous vascular and non-vascular chest problems, such as pulmonary embolism (PE), aortic dissection, or acute coronary syndrome, as well as pulmonary, pleural, or osseous lesions, must be taken into account. Nowadays, contrast-enhanced multi-detector-row computed tomography (CT) has replaced previous invasive diagnostic procedures and currently represents the imaging modality of choice when the clinical suspicion of PE or acute aortic syndrome is raised. At the same time, CT is capable of detecting a multitude of non-vascular causes of acute chest pain, such as pneumonia, pericarditis, or fractures. Recent technical advances in CT technology have also shown great advantages for non-invasive imaging of the coronary arteries. In patients with acute chest pain, the optimization of triage decisions and cost-effectiveness using cardiac CT in the emergency department have been repetitively demonstrated. Triple rule-out CT denominates an ECG-gated protocol that allows for the depiction of the pulmonary arteries, thoracic aorta, and coronary arteries within a single examination. This can be accomplished through the use of a dedicated contrast media administration regimen resulting in a simultaneous attenuation of the three vessel territories. This review is intended to demonstrate CT parameters and contrast media administration protocols for performing a triple rule-out CT and discusses radiation dose issues pertinent to the protocol. Typical life-threatening and non-life-threatening diseases causing acute chest pain are illustrate

Raw data-based iterative reconstruction in body CTA: evaluation of radiation dose saving potential

Objective: To evaluate prospectively, in patients undergoing body CTA, the radiation dose saving potential of raw data-based iterative reconstruction as compared to filtered back projection (FBP). Methods: Twenty-five patients underwent thoraco-abdominal CTA with 128-slice dual-source CT, operating both tubes at 120kV. Full-dose (FD) images were reconstructed with FBP and were compared to half-dose (HD) images with FBP and HD-images with sinogram-affirmed iterative reconstruction (SAFIRE), both reconstructed using data from only one tube-detector-system. Image quality and sharpness of the aortic contour were assessed. Vessel attenuation and noise were measured, contrast-to-noise-ratio was calculated. Results: Noise as image quality deteriorating artefact occurred in 24/25 (96%) HD-FBP but not in FD-FBP and HD-raw data-based iterative reconstruction datasets (p  0.05). Lowest noise was found for HD-raw data-based iterative reconstruction (7.23HU), being 9.4% lower than that in FD-FBP (7.98HU, p 50% while maintaining image quality. Key Points • Raw data-based iterative reconstruction reduces image noise and improves image quality as compared to filtered back projection • At a similar radiation dose, raw data-based iterative reconstruction improves the sharpness of vessel contours • In body CTA a dose reduction of >50% might be possible when using raw data-based iterative reconstructions, while image quality can be maintaine

Hepatic teratoma and peritoneal gliomatosis: a case report

The hepatic teratoma is a very rare entity of which only 25 cases have been published so far. In our case the hepatic teratoma is associated with peritoneal gliomatosis, which is an indicator for an ongoing peritoneal spread of a teratoma. Wall calcifications and the homogeneity as well as the well defined border misled the radiologist to the diagnosis of an echinococcal cyst, which is the most common differential diagnosis, however the hepatic teratoma has to be taking into consideration when dealing with unclear hepatic cysts, although it is very rare

MRI of the temporo-mandibular joint: which sequence is best suited to assess the cortical bone of the mandibular condyle? A cadaveric study using micro-CT as the standard of reference

Objective: To determine the best suited sagittal MRI sequence out of a standard temporo-mandibular joint (TMJ) imaging protocol for the assessment of the cortical bone of the mandibular condyles of cadaveric specimens using micro-CT as the standard of reference. Methods: Sixteen TMJs in 8 human cadaveric heads (mean age, 81years) were examined by MRI. Upon all sagittal sequences, two observers measured the cortical bone thickness (CBT) of the anterior, superior and posterior portions of the mandibular condyles (i.e. objective analysis), and assessed for the presence of cortical bone thinning, erosions or surface irregularities as well as subcortical bone cysts and anterior osteophytes (i.e. subjective analysis). Micro-CT of the condyles was performed to serve as the standard of reference for statistical analysis. Results: Inter-observer agreements for objective (r = 0.83-0.99, P < 0.01) and subjective (κ = 0.67-0.88) analyses were very good. Mean CBT measurements were most accurate, and cortical bone thinning, erosions, surface irregularities and subcortical bone cysts were best depicted on the 3D fast spoiled gradient echo recalled sequence (3D FSPGR). Conclusion: The most reliable MRI sequence to assess the cortical bone of the mandibular condyles on sagittal imaging planes is the 3D FSPGR sequence. Key Points : • MRI may be used to assess the cortical bone of the TMJ. • Depiction of cortical bone is best on 3D FSPGR sequences. • MRI can assess treatment response in patients with TMJ abnormalitie