Initial experience with a state-of-the-art mobile head CT scanner for use in neurointensive care units.

OBJECTIVE: Mobile head computed tomography (CT) scanners can reduce transport-related complications in neurointensive care unit (NICU) patients and decrease the burden on NICU staff; however, the initial investment cost and reduced image quality of early mobile scanners have prevented their widespread clinical use. Here, we report our initial experience with a novel 32-row mobile CT scanner for use in NICUs. METHODS: Over a 2-year period, 107 patients received a mobile head CT scan. The technical characteristics of the scanner and the organizational procedures are described in detail. Patient characteristics were retrospectively collected and image quality was subjectively evaluated on a Likert scale ranging from 0 to 5 and compared with a stationary CT scanner. RESULTS: Mobile head CT was used for follow-up of intracranial hemorrhage in 51%, routine postoperative imaging in 28%, evaluation of neurological deterioration in 14%, bedside monitoring after external ventricular drain placement in 4%, and follow-up of ischemic stroke in 3% of cases. Diagnostic imaging quality was achieved in all cases, eliminating the need for stationary CT scanning. The overall image quality of mobile CT (median 4 points) was inferior to that of conventional stationary CT (median 5 points, p < 0.01), but was rated with 4 or 5 points in the majority of cases. CONCLUSIONS: State-of-the-art mobile CT was found to be easy to use and maneuver and has the potential to expedite the diagnosis of NICU patients and reduce staff workload. Image quality was adequate for common NICU issues.

State-of-the-art mobile head CT scanner delivers nearly the same image quality as a conventional stationary CT scanner.

The use of mobile head CT scanners in the neurointensive care unit (NICU) saves time for patients and NICU staff and can reduce transport-related mishaps, but the reduced image quality of previous mobile scanners has prevented their widespread clinical use. This study compares the image quality of SOMATOM On.Site (Siemens Healthineers, Erlangen, Germany), a state-of-the-art mobile head CT scanner, and a conventional 64-slice stationary CT scanner. The study included 40 patients who underwent head scans with both mobile and stationary scanners. Gray and white matter signal and noise were measured at predefined locations on axial slices, and signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were calculated. Artifacts below the cranial calvaria and in the posterior fossa were also measured. In addition, image quality was subjectively assessed by two radiologists in terms of corticomedullary differentiation, subcalvarial space, skull artifacts, and image noise. Quantitative measurements showed significantly higher image quality of the stationary CT scanner in terms of noise, SNR and CNR of gray and white matter. Artifacts measured in the posterior fossa were higher with the mobile CT scanner, but subcalvarial artifacts were comparable. Subjective image quality was rated similarly by two radiologists for both scanners in all domains except image noise, which was better for stationary CT scans. The image quality of the SOMATOM On.Site for brain scans is inferior to that of the conventional stationary scanner, but appears to be adequate for daily use in a clinical setting based on subjective ratings.

Incidental finding of a bilateral absence of the superior vena cava.

Bilateral absence of the superior vena cava is associated with rhythm and structural abnormalities and is diagnosed incidentally either during imaging procedures or venous catheterization or pacemaker implantation. Knowledge of this entity is important to allow proper referral, medical management of its associated abnormalities, and risk reduction in certain interventions.

Evolution of RAS Mutational Status in Liquid Biopsies During First-Line Chemotherapy for Metastatic Colorectal Cancer.

Treatment options for patients with metastatic colorectal cancer (mCRC) are limited. This particularly affects the largest group of patients with RAS mutations, who are considered ineligible for therapy with antiEGFR antibodies. In this liquid biopsy-based study, we performed the first in-depth analysis of the RAS mutational status in initially RAS-mutated patients during first-line therapy. RAS status of twelve patients with initially RAS-mutated mCRC was monitored longitudinally in 69 liquid biopsy samples. We focused on patients with stable disease (SD) or partial remission (PR) during first-line therapy (11 patients). Detection of fragmented RAS-mutated circulating cell-free tumor DNA (ctDNA) in plasma was performed by digital-droplet PCR (ddPCR) and BEAMing. Patients' total tumor masses were determined by measuring the tumor volumes using CT scan data. All patients with PR or SD at first follow-up showed a significant decrease of RAS mutational load. In ten patients (91%), the ctDNA-based RAS mutational status converted to wild-type in ddPCR and BEAMing. Remarkably, conversions were observed early after the first cycle of chemotherapy. Plasma concentration of ctDNA was controlled by determination of methylated WIF1-promotor ctDNA burden as a second tumor marker for mCRC. Persistent presence of methylated WIF1-promotor fragments confirmed the ongoing release of ctDNA during treatment. In patients with initially RAS-mutated mCRC, RAS mutations rapidly disappeared during first-line therapy in liquid biopsy, independent of type and intensity of chemotherapy and irrespective of anti-VEGF treatments. Following our results demonstrating conversion of RAS-mutational status, potential effectiveness of anti-EGFR antibodies in selected patients becomes an attractive hypothesis for future studies.