Markers of chemotherapy efficacy in metastatic colorectal cancer (mCRC) are essential for optimization of treatment strategies. We evaluated the applicability of early changes in circulating tumor DNA (ctDNA) as a marker of therapeutic efficacy. This prospective study enrolled consecutive patients with mCRC receiving a first- or second-line chemotherapy. CtDNA was assessed in plasma collected before the first (C), second (C) and/or third (C) chemotherapy cycle, using picodroplet-digital PCR assays based either on detection of gene mutation () or hypermethylation (). CT scans were centrally assessed using RECIST v1.1 criteria. Multivariate analyses were adjusted on age, gender, ECOG performance status (PS), metastatic synchronicity, and treatment line. Eighty-two patients with mCRC treated in first- (82.9%) or second- (17.1%) line chemotherapy were included. Patients with a high (>10 ng/mL) versus low (≤0.1 ng/mL) ctDNA concentration at C had a shorter overall survival (OS; 6.8 vs. 33.4 months: adjusted HR, 5.64; 95% CI, 2.5-12.6; < 0.0001). By analyzing the evolution of the ctDNA concentration between C and C or C (C), we classified the patients in two groups (named "good" or "bad ctDNA responders"). In multivariate analysis, patients belonging to the group called "good ctDNA responder" ( = 58) versus "bad ctDNA responder" () had a better objective response rate ( < 0.001), and a longer median progression-free survival (8.5 vs. 2.4 months: HR, 0.19; 95% CI, 0.09-0.40; < 0.0001) and OS (27.1 vs. 11.2 months: HR, 0.25; 95% CI, 0.11-0.57; < 0.001). This study suggests that early change in ctDNA concentration is a marker of therapeutic efficacy in patients with mCRC. .

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Occult liver micrometastases in rats generate changes in liver perfusion that can be detected with CT.

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Placental perfusion can be calculated by using dynamic contrast-enhanced MR imaging, as shown in this mouse model.

Placental perfusion and permeability can be measured in vivo by using high gadolinium doses and a dual-echo MR imaging sequence.

PURPOSE: This study was designed to evaluate prospectively magnetic resonance imaging for the prediction of the circumferential resection margin in rectal cancer to identify in which patient magnetic resonance imaging could accurately assess the circumferential resection margin before surgery and in which patients it could not. METHODS: During a 17-month period, a preoperative magnetic resonance imaging for the assessment of circumferential resection margin was obtained prospectively in 38 patients with mid or low rectal cancer. The agreement of magnetic resonance imaging and pathologic examination for assessment of circumferential resection margin was analyzed. RESULTS: Overall, magnetic resonance imaging agreed with histologic examination of the circumferential resection margin assessment in 28 patients (73 percent; = 0.47). In all cases of disagreement between magnetic resonance imaging and pathology, magnetic resonance imaging overestimated the circumferential resection margin involvement. For the 11 patients with mid rectal cancer, circumferential resection margin was well predicted by magnetic resonance imaging in all cases ( = 1). For 27 patients with low rectal tumor, overall agreement between magnetic resonance imaging and histologic assessment was 63 percent ( = 0.35). Agreement was 22 percent ( = 0.03) for the 9 patients with low anterior and 83 percent ( = 0.67) for the 18 patients with low posterior rectal tumor. Univariate analysis revealed that only low and anterior rectal tumor was risk factor of overestimation of the circumferential resection margin by magnetic resonance imaging. CONCLUSIONS: Although magnetic resonance imaging remains the best imaging tool for the preoperative assessment of the circumferential resection margin in patients with rectal cancer, it can overestimate the circumferential resection margin involvement in low and anterior tumor with the risk of overtreating the patients. [

The observed association between f and fetal weight suggests that fMRI could be suitable for studying placental insufficiency and for identifying risk of SGA.