Prognostic value of midtreatment FDG-PET in oropharyngeal cancer.

BACKGROUND: Prognostic metabolic imaging indices are needed for risk stratification for patients with locally advanced oropharyngeal cancer. METHODS: We retrospectively examined pretreatment and midtreatment fluorodeoxyglucose-positron emission tomography (FDG-PET) parameters in patients with locally advanced oropharyngeal cancer who were treated with definitive chemoradiation. RESULTS: A total of 74 patients were evaluated. Pretreatment metabolic tumor volume (MTV) using threshold of 50% standardized uptake value (SUV) maximum (MTV50% ) was associated with progression-free survival (PFS; p = .003; hazard ratio [HR] = 1.57 per 10 cc; 95% confidence interval [CI] = 1.17-2.11) and overall survival (OS; p = .01; HR = 1.36 per 10 cc; 95% CI = 1.07-1.74). Midtreatment MTV using a threshold of SUV 2.0 (MTV2.0 ) was associated with PFS (p < .001; HR = 1.24 per 10 cc; 95% CI = 1.10-1.39) and OS (p = .009; HR = 1.21 per 10 cc; 95% CI = 1.05-1.39). Nodal total lesion glycolysis (TLG) velocity >5% decrease/week was associated with improved PFS (p = .04; HR = 0.37; 95% CI = 0.15-0.95). CONCLUSION: Metabolic response during chemoradiation is associated with survival in locally advanced oropharyngeal cancer and may aid with risk-adapting treatment. © 2016 Wiley Periodicals, Inc. Head Neck 38: First-1478, 2016.

Small animal micro-CT colonography.

Microcomputed tomography colonography (mCTC) is a new method for detecting colonic tumors in living animals and estimating their volume, which allows investigators to determine the spontaneous fate of individually annotated tumors as well as their response to chemotherapeutics. This imaging platform was developed using the Min mouse, but is applicable to any murine model of human colorectal cancer. MicroCT is capable of 20 micron resolution, however, 100 microns is sufficient for this application. Scan quality is primarily dependent on animal preparation with the most critical parameters being proper anesthesia, bowel cleansing, and sufficient insufflation. The detection of colonic tumors is possible by both 2D and 3D rendering of image data. Tumor volume is estimated using a semi-automated five-step process which is based on three algorithms within the Amira software package. The estimates are precise, accurate and reproducible enabling changes in volume as small as 16% to be readily observed. Confirmation of mCTC observations by gross examination and histology is sometimes useful in this otherwise non-invasive protocol. Finally, mCTC is compared to other newly developed small animal imaging platforms including microMRI and microoptical colonoscopy. A major advantage of these platforms is that investigators can be perform longitudinal studies, which often have much greater statistical power than traditional cross-sectional studies; consequently, fewer animals are required for testing.

Longitudinal assessment of colonic tumor fate in mice by computed tomography and optical colonoscopy.

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the relative merits of micro-computed tomograph colonography (mCTC) and optical colonoscopy (OC) for longitudinal studies of colonic tumors in mice. MATERIALS AND METHODS: Colonic tumors in mice carrying the Min allele of Apc were followed over several weeks using mCTC and OC. A total of 146 colonic tumors were monitored: 62 in 32 untreated Min mice, 53 in 43 Min mice treated with 5-fluorouracil (5-FU), and 31 in 17 Min mice treated with piroxicam. RESULTS: Colonic tumors in Min mice had three different spontaneous fates: 29 grew, 24 remained static, and 9 regressed. Treating Min mice with 5-FU increased the percentage of regressing tumors from 15% to 58%. The response was dependent in part on the initial size of the tumor. By contrast, treating Min mice with piroxicam did not alter colonic tumor fate. CONCLUSIONS: mCTC and OC can be used to determine the spontaneous fates of colonic tumors in mice and to document their individual responses to treatment. The ability to follow individually annotated colonic tumors reduces the number of mice needed for testing.

Reproducibility of tumor volume measurement at microCT colonography in living mice.

RATIONALE AND OBJECTIVES: We sought to demonstrate the viability of microcomputed tomographic colonography (muCTC) as a tool for monitoring tumorigenesis in mouse models of human colorectal cancer during prospective longitudinal studies. The precision and accuracy of volumetric measurements were determined to assess whether changes in tumor volume over time were readily detectable. MATERIALS AND METHODS: All animal studies were conducted under the guidelines set forth by the Institutional Animal Care and Use Committee of the American Association for Assessment and Accreditation of Laboratory Animal Care. muCTC was performed on C57BL/6J (B6) mice carrying the Min allele of Apc, ultimately yielding 18 scans. Assessments of scan quality and tumor volume were both performed once per week over 8 weeks. RESULTS: Scans with a good quality rating had a mean standard deviation in tumor volume measurement of 8%. By contrast, scans with a poor quality rating had a mean standard deviation in tumor volume measurement of 35%. Variables affecting muCTC scan quality in living mice included bowel preparation, motion artifact, and tumor morphology. Tumor volume measurements were highly correlated with tumor weight (r2 = 0.87). CONCLUSIONS: The reproducibility of tumor volume measurement at muCTC in living mice makes prospective longitudinal evaluation of colonic tumor response feasible. For muCTC scans of good quality, a 16% change in tumor volume can be detected at the 95% confidence level.