The current evidence on the clinical implementation of iterative reconstruction into CT protocols shows substantial promise for major improvements in image quality, chiefly noise reduction—with subsequent radiation dose reduction—and artifact suppression. Owing to recent advances in computing power, iterative reconstruction (IR) algorithms have become a clinically viable option in computed tomographic (CT) imaging. Substantial evidence is accumulating about the advantages of IR algorithms over established analytical methods, such as filtered back projection. IR improves image quality through cyclic image processing. Although all available solutions share the common mechanism of artifact reduction and/or potential for radiation dose savings, chiefly due to image noise suppression, the magnitude of these effects depends on the specific IR algorithm. In the first section of this contribution, the technical bases of IR are briefly reviewed and the currently available algorithms released by the major CT manufacturers are described. In the second part, the current status of their clinical implementation is surveyed. Regardless of the applied IR algorithm, the available evidence attests to the substantial potential of IR algorithms for overcoming traditional limi...

The aim of this study was to determine whether texture features of rectal cancer on T2-weighted (T2w) magnetic resonance images can predict tumoral response in patients treated with neoadjuvant chemoradiotherapy (CRT). We prospectively enrolled 15 consecutive patients (6 women, 63.2 ± 13.4 years) with rectal cancer, who underwent pretreatment and midtreatment 3-T magnetic resonance imaging. Treatment protocol consisted of neoadjuvant CRT with oxaliplatin and 5-fluorouracile. Texture analysis using a filtration-histogram technique was performed using a commercial research software algorithm (TexRAD Ltd, Somerset, England, United Kingdom) on unenhanced axial T2w images by manually delineating a region of interest around the tumor outline for the largest cross-sectional area. The technique selectively filters and extracts textures at different anatomic scales followed by quantification of the histogram using kurtosis, entropy, skewness, and mean value of positive pixels. After CRT, all patients underwent complete surgical resection and the surgical specimen served as the gold standard. Six patients showed pathological complete response (pCR), and 4 patients, partial response (PR). Five patients were classified as nonresponders (NRs). Pretreatment medium texture-scale quantified as kurtosis was significantly lower in the pCR subgroup in comparison with the PR + NR subgroup (P = 0.01). Midtreatment kurtosis without filtration was significantly higher in pCR in comparison with PR + NR (P = 0.045). The change in kurtosis between midtreatment and pretreatment images was significantly lower in the PR + NR subgroup compared with the pCR subgroup (P = 0.038). Pretreatment area under the receiver operating characteristic curves, to discriminate between pCR and PR + NR, was significantly higher for kurtosis (0.907, P < 0.001) compared with all other parameters. The optimal cutoff value for pretreatment kurtosis was 0.19 or less. Using this value, the sensitivity and specificity for pCR prediction were 100% and 77.8%, respectively. Texture parameters derived from T2w images of rectal cancer have the potential to act as imaging biomarkers of tumoral response to neoadjuvant CRT.

OBJECTIVE. Dual-energy CT (DECT) is an innovative imaging technique that operates on the basic principle of application of two distinct energy settings that make the transition from CT attenuation–based imaging to material-specific or spectral imaging. The purpose of this review is to describe the use of DECT in oncology. CONCLUSION. Applications of DECT in clinical practice are based on two capabilities: material differentiation and material identification and quantification. The capability of obtaining different material-specific datasets (iodine map, virtual unenhanced, and monochromatic images) in the same acquisition can improve lesion detection and characterization. This approach can also affect evaluation of the response to therapy and detection of oncology-related disorders. DECT is an innovative imaging technique that can dramatically affect the care of oncologic patients.

Rectal cancer is a common malignancy that continues to have a highly variable outcome, with local pelvic recurrence after surgical resection usually leading to incurable disease. The success of tumor excision depends largely upon accurate tumor staging and appropriate surgical technique, although the results of recent surgical trials indicate that evaluation of the involvement of the mesorectal fat and mesorectal fascia is even more important than T staging for treatment planning. Magnetic resonance (MR) imaging is increasingly being used to evaluate tumor resectability in patients with rectal cancer and to determine which patients can be treated with surgery alone and which will require radiation therapy to promote tumor regression. High-spatial-resolution MR imaging has proved useful in clarifying the relationship between a tumor and the mesorectal fascia, which represents the circumferential resection margin at total mesorectal excision. Phased-array surface coil MR imaging in particular plays a vital role in the therapeutic management of rectal cancer. At present, phased-array MR imaging best fulfills the clinical requirements for preoperative staging of rectal cancer. However, preoperative evaluation of the other prognostic factor, nodal status, is still problematic, and further studies will be needed to better define the role of MR imaging in this context.