Anal Cancer.

Anal cancer is a rare cancer, comprising less than 5% of gastrointestinal tract malignancies. Diagnosis of anal canal cancer can be difficult given that presenting symptoms are similar to those of benign anorectal diseases. General surgeons who encounter suspected anal canal cancer need to have a good understanding of the anatomy of the anal canal, high index of suspicion for malignancy, and low threshold to biopsy lesions when indicated. This article discusses the most commonly encountered anal canal tumors, the evaluation of these tumors, and their management. The foundation for successful therapy includes timely diagnosis, accurate staging, and routine surveillance.

The sensitivity of standard radiographic foot measures to misalignment.

BACKGROUND: The purpose of this study was to identify the effects that X-ray source misalignment has on common measurements made from anterior-poster (AP) and medial-lateral (ML) view foot radiographs. METHODS: A cadaveric foot model was used to obtain ML radiographs with ±25 degree transverse plane misalignment. From these images the calcaneal pitch angle (CPA) and lateral talometatarsal angle (LTMA) were measured. AP images were captured with up to 30 degree sagittal plane misalignment as well as ±15 degree misalignment in the transverse plane at each sagittal angle. From these images the talonavicular coverage angle (TNCA) and talometatarsal angle (TMA) were measured. RESULTS: On the ML images, the CPA was sensitive to transverse plane misalignment from -10 to -25 degrees and from 15 to 25 degrees (P < .005). The LTMA was a more reliable measurement than the CPA and did not demonstrate sensitivity to transverse plane misalignment. On the AP images, the TNCA and TMA were not sensitive to sagittal plane misalignment alone. However, at 0, 10, and 15 degrees sagittal misalignment the TNCA showed sensitivity to transverse plane misalignment (P < .0083). CONCLUSION: Misalignment of an X-ray source can lead to errors in the measurement of foot radiographic parameters, especially the CPA when there is transverse plane misalignment and the TNCA when there is both sagittal and transverse plane misalignment. The LTMA and TMA can be measured reliably, even with significant misalignment present. CLINICAL RELEVANCE: If a researcher or clinician is interested in measuring the CPA or TNCA, the current best practices guidelines for obtaining ML and AP images should be closely followed.