Search

To investigate whether MRI-based texture analysis improves diagnostic performance for the diagnosis of parotid gland tumors compared to conventional radiological approach. Patients with parotid gland tumors who underwent salivary glands MRI between 2008 and 2019 were retrospectively selected. MRI analysis included a qualitative assessment by two radiologists (one of which subspecialized on head and neck imaging), and texture analysis on various sequences. Diagnostic performances including sensitivity, specificity, and area under the receiver operating characteristic curve (AUROC) of qualitative features, radiologists' diagnosis, and radiomic models were evaluated. Final study cohort included 57 patients with 74 tumors (27 pleomorphic adenomas, 40 Warthin tumors, 8 malignant tumors). Sensitivity, specificity, and AUROC for the diagnosis of malignancy were 75%, 97% and 0.860 for non-subspecialized radiologist, 100%, 94% and 0.970 for subspecialized radiologist and 57.2%, 93.4%, and 0.927 using a MRI radiomics model obtained combining texture analysis on various MRI sequences. Sensitivity, specificity, and AUROC for the differential diagnosis between pleomorphic adenoma and Warthin tumors were 81.5%, 70%, and 0.757 for non-subspecialized radiologist, 81.5%, 95% and 0.882 for subspecialized radiologist and 70.8%, 82.5%, and 0.808 using a MRI radiomics model based on texture analysis of T2 weighted sequence. A combined radiomics model obtained with all MRI sequences yielded a sensitivity of 91.5% for the diagnosis of pleomorphic adenoma. MRI qualitative radiologist assessment outperforms radiomic analysis for the diagnosis of malignancy. MRI predictive radiomics models improves the diagnostic performance of non-subspecialized radiologist for the differential diagnosis between pleomorphic adenoma and Warthin tumor, achieving similar performance to the subspecialized radiologist. Radiologists outperform radiomic analysis for the diagnosis of malignant parotid gland tumors, with some MRI qualitative features such as ill-defined margins, perineural spread, invasion of adjacent structures and enlarged lymph nodes being highly specific for malignancy. A radiomic model based on texture analysis of T2 weighted images yields higher specificity for the diagnosis of pleomorphic adenoma compared to a radiologist non-subspecialized in head and neck radiology, thus minimizing false-positive pleomorphic adenoma diagnosis rate and reducing unnecessary surgical complications. [ABSTRACT FROM AUTHOR]

Objective: To analyze lung lesion volume variations by contouring on cone-beam CT (CBCT) images to evaluate the early predictive parameters of stereotactic ablative radiation therapy (SABR) treatment response. Methods: The prescribed dose of SABR was varied according to the tumour site (central or peripheral) and maximum diameter of the lesions by using a strategy of risk-adapted dose prescription with a dose range between 48 and 70 Gy in 3-10 consecutive fractions. For the purpose of the analysis, the gross tumour volume (GTV) was recontoured for each patient at first and last CBCT using two lung levels/windows: (a) -600/1000 HU and (b) -1000/250 HU. Univariate analysis was performed to evaluate a correlation between lung lesion variations on CBCT using the two levels/windows and treatment response 6 months after SABR. Independent variables were the number of fractions, time between initial and final fraction, biologically effective dose and pre-SABR GTV. Cut points of lesion volume reduction were evaluated to determine the correlation with complete response 6 months after SABR. Results: 41 lung lesions were evaluated. 82 lung lesions were recontoured for each CBCT level/window. A lung lesion shrinkage of at least 20% was revealed to be statistically related to complete response 6 months after SABR for both the CBCT levels/windows used. The probability of complete response ranged between six and eight times higher in respect to CBCT levels/windows -600/1000 HU and -1000/250 HU, respectively, compared with patients without a lesion shrinkage of 20% at the last session of SABR. Conclusion: According to current findings, a lung lesion shrinkage of at least 20% at the last session of SABR could be predictable of complete response 6 months thereafter. Further investigations about this topic are needed. [ABSTRACT FROM AUTHOR]

Objective: To compare the influence of different iodinated contrast media with several dilutions on plaque attenuation in an ex vivo coronary model studied by multislice CT coronary angiography. Methods: In six ex vivo left anterior descending coronary arteries immersed in oil, CT (slices/collimation 64x0.625mm, temporal resolution 210ms, pitch 0.2) was performed after intracoronary injection of a saline solution, and solutions of a dimeric isosmolar contrast medium (lodixanol 320 mgI ml-1) and a monomeric high-iodinated contrast medium (lomeprol 400 mgI ml-1) with dilutions of 1/80 (low concentration), 1/50 (medium concentration), 1/40 (high concentration) and 1/20 (very high concentration). Two radiologists drew regions of interest in the lumen and in calcified and non-calcified plaques for each solution. 29 cross-sections with non-calcified plaques and 32 cross-sections with calcified plaques were evaluated. Results: Both contrast media showed different attenuation values within lumen and plaque (p<0.0001). The correlation between lumen and non-calcified plaque values was good (lodixanol r=0.793, lomeprol r=0.647). Clustered medium- and high-concentration solutions showed similar plaque attenuation values, signal-to-noise ratios (SNRs) (non-calcified plaque: medium solution SNR 31.3 ± 15 vs 31.4±20, high solution SNR 39.4±17 vs 37.4± 22; calcified plaque: medium solution SNR 305.2±133 vs 298.8± 132, high solution SNR 323.9±138 vs 293±123) and derived contrast-to-noise ratios (p>0.05). Conclusion: Differently iodinated contrast media have a similar influence on plaque attenuation profiles. Advances in knowledge: Since iodine load affects coronary plaque attenuation linearly, different contrast media may be equally employed for coronary atherosclerotic plaque imaging. [ABSTRACT FROM AUTHOR]

Rupture and secondary infection are common complications of hydatid cyst in the liver. Ultrasound and CT findings are reported in a case of hydatid cyst which has ruptured directly into the left colon. Rupture of hydatid cyst into a hollow viscus is extremely rare. CT demonstrated partial drainage of the cyst contents with the creation of an air-fluid level.