Aim To subjectively and objectively evaluate the feasibility and diagnostic reliability of a low-dose, long-pitch dual-source chest CT protocol on third-generation dual-source CT (DSCT) with spectral shaping at 100Sn kVp for COVID-19 patients. Materials and methods Patients with COVID-19 and positive swab-test undergoing to a chest CT on third-generation DSCT were included. The imaging protocol included a dual-energy acquisition (HD-DECT, 90/150Sn kVp) and fast, lowdose, long-pitch CT, dual-source scan at 100Sn kVp (LDCT). Subjective (Likert Scales) and objective (signal-to-noise and contrast-to-noise ratios, SNR and CNR) analyses were performed; radiation dose and acquisition times were recorded. Nonparametric tests were used. Results The median radiation dose was lower for LDCT than HD-DECT (Effective dose, ED: 0.28 mSv vs. 3.28 mSv, p = 0.016). LDCT had median acquisition time of 0.62 s (vs 2.02 s, p = 0.016). SNR and CNR were significantly different in several thoracic structures between HD-DECT and LDCT, with exception of lung parenchyma. Qualitative analysis demonstrated significant reduction in motion artifacts (p = 0.031) with comparable diagnostic reliability between HD-DECT and LDCT. Conclusions Ultra-low-dose, dual-source, fast CT protocol provides highly diagnostic images for COVID-19 with potential for reduction in dose and motion artifacts.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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OBJECTIVE.Wedge-shaped areas of increased signal intensity surrounding focal hepatic lesions on T2-weighted images have been described as an occasional finding in patients with hepatic metastases. We reviewed MR images of patients with benign and malignant focal hepatic lesions to determine the prevalence and diagnostic sig- However, the appearance of these wedge-shaped areas in a patient with cancer should suggest a metastasis. The possibility that hepatic lesions could be obscured by these wedge-shaped areas also should be considered when response to treatment is being evaluated.

High-resolution magnetic resonance imaging (MRI) was used to study 16 resected rectosigmoid specimens of patients treated with total colectomy for severe ulcerative colitis (UC). Six normal colon specimens were also studied as a control group. Moreover, a parallel study of the pelvis of 24 patients with a proven diagnosis of UC was performed with the same MR system. Both in vitro and in vivo MRI findings [thickening and signal intensity (SI)] of the mural layers were qualitatively evaluated by two radiologists and compared with gross and microscopic aspects. In vitro results showed that MRI was able to identify all layers of the colonic wall. In particular in UC specimens, MRI identified thickening and the peculiar abnormal hyperintensity of the mucosal and submucosal layers on spin-echo (SE) T1-weighted images. In vivo results confirmed the high-signal intensity of the mucosal and submucosal layers. These findings were not observed in the control group in which the superficial layers appeared low in intensity on SE T1 images. Our preliminary experience suggests that MRI should be considered a new imaging modality for detecting UC colonic wall changes.

To identify changes induced by chemotherapy in hepatic metastases, 34 patients with metastases underwent magnetic resonance (MR) imaging before the start of systemic chemotherapy and monthly thereafter. The number, size, and morphologic patterns of the lesions and changes in quantitative parameters (signal-to-noise ratio [S/N]], contrast-to-noise ratio, and signal intensity ratio) were evaluated and correlated with response to treatment and prognosis. After treatment, seven patients showed a partial response, 18 had stable disease, and nine had progressive disease. No relevant changes in the patterns of the lesions were observed. Quantitative data showed that patients with a good prognosis had an increase in S/N on T1-weighted images and a relative decrease on T2-weighted images; patients with a poor prognosis showed a decrease in S/N on T1-weighted images and an increase on T2-weighted images. The differences between patient groups were significant for both T1- and T2-weighted images. This study demonstrates the value of MR imaging in follow-up of liver metastases and suggests the usefulness of quantitative MR imaging data.