Introduction

Article Outline

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Approximately 5 years have gone by since the last publication of an update on imaging colorectal disease in Seminars in Colon and Rectal Surgery. Rapid technological advancements in radiology require periodic updates on the status and utility of emerging imaging techniques, as practicing surgeons are faced with an increasing availability of an ever-growing number of imaging modalities to evaluate their patients. This issue aims to provide guidance for state-of-the-art workup of common or challenging clinical issues such as pelvic floor abnormalities, fistulae-in-ano, and ileo-anal pouch imaging. Furthermore, we asked authors to discuss emerging imaging technology such as virtual colonoscopy and PET/CT and to provide an outlook on molecular imaging techniques, all of which are expected to impact the diagnosis and treatment of colorectal patients in the near future.

Drs. Kim and Pickhardt present a wealth of information about all aspects of their high-volume state-of-the-art colorectal cancer screening program utilizing CT colonography (CTC). Their practice at the University of Wisconsin is widely considered a leader in this field and we are very fortunate to be able to include this article.

The authors discuss not only advances in hardware and software technology but also specific protocol techniques found to be equivalent to optical colonoscopy. CTC issues relevant to the colorectal surgeon are addressed. Specifically, the authors provide guidance for lesion localization for preoperative planning, synchronous lesion assessment, and submucosal lesion characterization. The utility of standardized lexicon and reporting system is highlighted.

In their comprehensive article, Drs. Sheehy, Fennessy, and van den Abbeele introduce the reader into the history and underlying principles of PET/CT. They review the role and accuracy of this imaging modality in the initial diagnosis of colorectal malignancy and preoperative staging, in the evaluation of recurrent or metastatic disease, before metastasis resection, in evaluating response to chemotherapy, radiotherapy, and radiofrequency ablation, as well as its cost-effectiveness and impact on management. The authors then discuss limitations in certain clinical scenarios, in particular, the evaluation of small lesions and those with less FDG avid tumor histology.

Dr. Fielding contributes a very valuable article on pelvic floor (PF) imaging in female patients with PF decompensation, specifically those who present with multi-compartment damage, have failed previous surgery, or have other medical conditions that prohibit a good physical examination. Her thorough and practical discussion of MR technique and imaging findings provides the reader with a better understanding of how MRI can guide surgical planning for an optimal repair procedure.

Drs. Knechtges and colleagues discuss state-of-art imaging of fistula-in-ano, in particular, the use of anal endosonography and pelvic MRI. In addition to a discussion of the clinical factors and classification schemes, the authors compare and contrast the utility of both imaging modalities. Comments on necessary hardware and protocols are included. Both the normal anatomy and the pathology are well depicted, and corresponding illustrations provide the practicing surgeon with a thorough understanding of fistula-in-ano imaging.

Drs. Scheirey and Scholz bring the reader up to date on imaging of the ileoanal pouch, specifically the normal postoperative appearance and the imaging appearance of typical complications such as acute leaks, nonspecific pouchitis, and small bowel obstructions. In addition to the conventional radiographic evaluation with barium enemas and contrast-enhanced CT, recent technical advancements in MRI make this modality a viable imaging alternative avoiding ionizing radiation.

Most of us are only too familiar with the limitations of traditional cross-sectional imaging modalities in the diagnosis of primary and metastatic colorectal malignancy. In their fascinating article, Drs. Mahmood and Upadhyay provide a glimpse of molecular imaging methods above and beyond PET/CT, which are just being introduced into clinical practice and which hold great promise to improve our ability to detect disease and monitor response to therapy. Specifically, the authors discuss the utility of combined administration of ultrasmall magnetic iron oxide nanoparticles with tailored MR imaging protocols, the use of near-infrared optical imaging probes permitting fluorescent endoscopy, and intraoperative imaging with activatable optical smart probes as near-term imaging paradigms.

We sincerely hope that the esteemed readers will find the articles of this issue helpful in their daily practice as well as stimulating in the reflection on cutting edge and emerging imaging technologies and how they may enhance the medicine we practice.