ABSTRACT
OBJECTIVE: To assess the radiation dose and image quality of ultra-low dose (ULD)-CT colonography (CTC) obtained with the combined use of automatic tube current (mAs) modulation with a quality reference mAs of 25 and sinogram-affirmed iterative reconstruction (SAFIRE), compared to low-dose (LD) CTC acquired with a quality reference mAs of 55 and reconstructed with filtered back projection (FBP). METHODS: Eighty-two patients underwent ULD-CTC acquisition in prone position and LD-CTC acquisition in supine position. Both ULD-CTC and LD-CTC protocols were compared in terms of radiation dose [weighted volume computed tomography dose index (CTDIvol ) and effective dose], image noise, image quality, and polyp detection. RESULTS: The mean effective dose of ULD-CTC was significantly lower than that of LD-CTC (0.98 and 2.69 mSv respectively, P < 0.0001) with an overall dose reduction of 63.2%. Image noise was comparable between ULD-CTC and LD-CTC (28.6 and 29.8 respectively, P = 0.09). There was no relevant difference when comparing image quality scores and polyp detection for both 2D and 3D images. CONCLUSION: ULD-CTC allows to significantly reduce the radiation dose without meaningful image quality degradation compared to LD-CTC.
Subject(s)
Algorithms , Colonic Diseases/diagnostic imaging , Colonography, Computed Tomographic/methods , Image Processing, Computer-Assisted/methods , Radiation Exposure , Radiographic Image Interpretation, Computer-Assisted/methods , Colonic Diseases/pathology , Colonic Diseases/radiotherapy , Humans , Patient Positioning , Prone Position , Radiotherapy Dosage , Retrospective StudiesABSTRACT
PURPOSE: The purpose of the article is to determine whether changes in apparent diffusion coefficient (ADC) values of locally advanced rectal cancer (LARC) obtained 2 weeks after the beginning of chemoradiation therapy (CRT) allow to predict treatment response and whether correlate with tumor histopathologic response. METHODS: Forty-three patients receiving CRT for LARC and 3.0T magnetic resonance imaging with diffusion-weighted sequences before treatment, 2 weeks during, and 8 weeks post the completion of CRT were included. ADC values were calculated at each time point and percentage of ADC changes at 2 weeks (ΔADC during) and 8 weeks (ΔADC post) were assessed. Data were correlated to surgical results and histopathologic tumor regression grade (TRG), according to Mandard's classification. ADC values and ΔADCs of complete responders (CR; TRG1) and non-complete responders (non-CR; TRG 2-5) were compared. Receiver-operating characteristic curve (ROC) analysis was used to assess diagnostic accuracy of ΔADC for differentiating CR from non-CR. The correlation with TRG was investigated using Spearman's rank test. RESULTS: ΔADC during and ΔADC post were significantly higher in CR (33.9% and 57%, respectively) compared to non-CR (13.5% and 2.2%, respectively) group (p = 0.006 and p < 0.001, respectively). ROC analysis revealed the following diagnostic performances: ΔADC during: AUC 0.78 (0.08), p = 0.004, cut-off 20.6% (sensitivity 75% and specificity 76.5%); ΔADC post: AUC 0.94 (0.04), p ≤ 0.001, cut-off 22% (sensitivity 95% and specificity 82.4%). Significant moderate and good negative correlation was found between ΔADC during and ΔADC post and TRG (r = - 0.418, p = 0.007; r = - 694, p ≤ 0.001, respectively). CONCLUSION: ΔADC at 2 weeks after the beginning of CRT is a reliable tool to early assess treatment response.
Subject(s)
Adenocarcinoma/diagnostic imaging , Adenocarcinoma/therapy , Chemoradiotherapy , Diffusion Magnetic Resonance Imaging/methods , Rectal Neoplasms/diagnostic imaging , Rectal Neoplasms/therapy , Adenocarcinoma/pathology , Adult , Aged , Female , Humans , Male , Middle Aged , Neoadjuvant Therapy , Neoplasm Grading , Preoperative Care , Prospective Studies , Rectal Neoplasms/pathology , Sensitivity and SpecificityABSTRACT
Many inflammatory and infectious entities may acutely affect the peritoneum causing a thickening of its layers. Unfortunately, several acute peritoneal diseases can have overlapping features, both clinically and at imaging. Therefore, the awareness of the clinical context, although useful, may be sometimes insufficient to identify the underlying cause. This article provides a specific computed tomography-based approach including morphologic characteristics of peritoneal thickening (e.g., smooth, irregular, or nodular) and ancillary findings to narrow the differential diagnosis of acute peritonitis.
