Comparative evaluation of non-contrast CAIPIRINHA-VIBE 3T-MRI and multidetector CT for detection of pulmonary nodules: In vivo evaluation of diagnostic accuracy and image quality.

PURPOSE: To evaluate the diagnostic accuracy, subjective image quality, and interobserver agreement of non-contrast Controlled Aliasing In Parallel Imaging Results In Higher Acceleration (CAIPIRINHA) volumetric interpolated breath-hold examination (VIBE) 3T magnetic resonance imaging (MRI) for the detection of pulmonary nodules with intra-individual comparison to computed tomography (CT). MATERIALS AND METHODS: We evaluated 54 patients (27 male, 27 female; mean age, 60.8 ± 11.5 years) who prospectively underwent thoracic 3T-MRI using CAIPIRINHA-VIBE sequences and chest CT. Diagnostic accuracy for the detection of lung nodules on CAIPIRINHA-VIBE MRI by three independent observers were compared to the reference standard CT. Subjective image quality was rated using a 5-point grading scale. Diagnostic accuracy was calculated and interobserver agreement was assessed using intraclass correlation coefficient (ICC). RESULTS: Sensitivity of 3T-MRI for the detection of pulmonary lesions compared to CT was 88.1% (95% confidence interval [CI]: 0.81-0.93) and specifity was 79.1% (95% CI: 0.50-0.95). Sensitivity for lesions <5mm was 77.2% (95% CI: 0.59-0.90) and for lesions from 5 to 10mm was 87.2% (95% CI: 0.76-0.94). Sensitivity for lesions >10mm was 100%. Observer ratings regarding subjective image quality were good to excellent for 3T-MRI (1.54) and CT (1.14) with almost perfect interobserver agreement for 3T-MRI and CT (ICC=0.83, 95% CI: 0.78-0.89; ICC=0.89, 95% CI: 0.85-0.94). CONCLUSIONS: Non-contrast CAIPIRINHA-VIBE 3T-MRI allows for the reliable detection of pulmonary lesions with a diameter >5mm in comparison with chest CT with high diagnostic accuracy, subjective image quality, and interobserver agreement.

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 (5s, group 1; 10s, group 2; 12s, group 3; 14s, 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 10s 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 (7.7s vs. 1.7s for group 1 vs. 2, 3 and 4). CONCLUSION: In high-pitch CT angiography using a start delay of 10s after a trigger threshold of 140 HU in the descending aorta is reached, a homogenous contrast along the z-axis is accomplished.

Dose and image quality of high-pitch dual source computed tomography for the evaluation of cervical lymph node status - comparison to regular 128-slice single source computed tomography.

PURPOSE: A high-pitch dual-source CT (DSCT) was compared to a standard single-source CT protocol in terms of dose and image quality for malignant lymphoma staging. MATERIALS AND METHODS: Data from 43 patients who underwent DSCT (group 1) of the neck for staging of malignant lymphoma and 40 patients who underwent regular single source CT (group 2) were investigated retrospectively. Volume CT dose index (CTDIvol), dose length product (DLP), background noise (BN), attenuation values, signal-to-noise-ratio (SNR), scan time, effective tube current-time product (eff. mAs), subjective diagnostic image quality and artifact burden were compared. RESULTS: CTDIvol (5.5 ± 0.8 mGy vs. 12.4 ± 1.4 mGy), DLP (172 ± 27 mGycm vs. 344 ± 60 mGycm, p<0.0001), eff. mAs (98 ± 15 mAs vs. 183 ± 20 mAs, p<0.0001) and scan time (0.64 ± 0.05 s vs. 8.21 ± 0.72 s) were lower for group 1. BN was higher (p<0.001) for group 1 with a mean difference of 2.6 HU. SNR for sternocleidomastoid and pectoral muscle was lower (6.6-12.3 vs. 7.8-19.1) for group 1. Subjective image quality (1.55 ± 0.6 vs. 1.42 ± 0.5) and artifact burden (1.62 ± 1.0 vs. 1.57 ± 0.9) were not rated significantly different (p=0.47 and p=0.80) with a good inter-observer agreement (κ=0.59-0.90). CONCLUSION: High-pitch DSCT allows reduction of patient dose for cervical lymphoma staging while diagnostic image quality is preserved.

Involvement of the transcription factor FoxM1 in contact inhibition.

Contact inhibition is a crucial mechanism regulating proliferation in vitro and in vivo. Although it is generally accepted that contact inhibition plays a pivotal role in maintaining tissue homeostasis, the molecular mechanisms of contact inhibition are still not fully understood. FoxM1 is known as a proliferation-associated transcription factor and is upregulated in many cancer types. Vice versa, anti-proliferative signals, such as TGF-ß and differentiation signals decrease FoxM1 expression. Here we investigated the role of FoxM1 in contact inhibition in fibroblasts. We show that protein expression of FoxM1 is severely and rapidly downregulated upon contact inhibition, probably by inhibition of ERK activity, which then leads to decreased expression of cyclin A and polo-like kinase 1. Vice versa, ectopic expression of FoxM1 prevents the decrease in cyclin A and polo-like kinase 1 and causes a two-fold increase in saturation density indicating loss of contact inhibition. Hence, we show that downregulation of FoxM1 is required for contact inhibition by regulating expression of cyclin A and polo-like kinase 1.