Follow-up imaging of anal cancer after treatment.

Anal cancer treatment response assessment can be challenging with both magnetic resonance imaging (MRI) and clinical evaluation considered essential. MRI, in particular, has shown to be useful for the assessment of treatment response, the detection of recurrent disease in follow up and surveillance, and the evaluation of possible post-treatment complications as well as complications from the tumor itself. In this review, we focus on the role of imaging, mainly MRI, in anal cancer treatment response assessment. We also describe the treatment complications that can occur, and the imaging findings associated with those complications.

A primer on rectal MRI in patients on watch-and-wait treatment for rectal cancer.

Total neoadjuvant treatment (TNT) for rectal cancer is becoming an accepted treatment paradigm and is changing the landscape of this disease, wherein up to 50% of patients who undergo TNT are able to avoid surgery. This places new demands on the radiologist in terms of interpreting degrees of response to treatment. This primer summarizes the Watch-and-Wait approach and the role of imaging, with illustrative "atlas-like" examples as an educational guide for radiologists. We present a brief literature summary of the evolution of rectal cancer treatment, with a focus on magnetic resonance imaging (MRI) assessment of response. We also discuss recommended guidelines and standards. We outline the common TNT approach entering mainstream practice. A heuristic and algorithmic approach to MRI interpretation is also offered. To illustrate management and common scenarios, we arranged the illustrative figures as follows: (I) Clinical complete response (cCR) achieved at the immediate post-TNT "decision point" scan time; (II) cCR achieved at some point during surveillance, later than the first post-TNT MRI; (III) near clinical complete response (nCR); (IV) incomplete clinical response (iCR); (V) discordant findings between MRI and endoscopy where MRI is falsely positive, even at follow-up; (VI) discordant cases where MRI seems to be falsely positive but is proven truly positive on follow-up endoscopy; (VII) cases where MRI is falsely negative; (VIII) regrowth of tumor in the primary tumor bed; (IX) regrowth outside the primary tumor bed; and (X) challenging scenarios, i.e., mucinous cases. This primer is offered to achieve its intended goal of educating radiologists on how to interpret MRI in patients with rectal cancer undergoing treatment using a TNT-type treatment paradigm and a Watch-and-Wait approach.

Restaging MRI of Rectal Adenocarcinoma after Neoadjuvant Chemoradiotherapy: Imaging Findings and Potential Pitfalls.

Rectal adenocarcinoma constitutes about one-third of all colorectal adenocarcinoma cases. Rectal MRI has become mandatory for evaluation of patients newly diagnosed with rectal cancer because it can help accurately stage the disease, impact the choice to give neoadjuvant therapy or proceed with up-front surgery, and even direct surgical dissection planes. Better understanding of neoadjuvant chemoradiotherapy effects on rectal tumors and recognition that up to 30% of patients can have a pathologic complete response have opened the door for the nonsurgical "watch-and-wait" management approach for rectal adenocarcinoma. Candidates for this organ-preserving approach should have no evidence of malignancy on all three components of response assessment after neoadjuvant therapy (ie, digital rectal examination, endoscopy, and rectal MRI). Hence, rectal MRI again has a major role in directing patient management and possibly sparing patients from unnecessary surgical morbidity. In this article, the authors discuss the indications for neoadjuvant therapy in management of patients with rectal adenocarcinoma, describe expected imaging appearances of rectal adenocarcinoma after completion of neoadjuvant therapy, and outline the MRI tumor regression grading system. Since pelvic sidewall lymph node dissection is associated with a high risk of permanent genitourinary dysfunction, it is performed for only selected patients who have radiologic evidence of sidewall lymph node involvement. Therefore, the authors review the relevant lymphatic compartments of the pelvis and describe lymph node criteria for determining locoregional nodal spread. Finally, the authors discuss limitations of rectal MRI, describe several potential interpretation pitfalls after neoadjuvant therapy, and emphasize how these pitfalls may be avoided. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Imaging of Anal Squamous Cell Carcinoma: Survey Results and Expert Opinion from the Rectal and Anal Cancer Disease-Focused Panel of the Society of Abdominal Radiology.

The role and method of image-based staging of anal cancer has evolved with the rapid development of newer imaging modalities and the need to address the rising incidence of this rare cancer. In 2014, the European Society of Medical Oncology mandated pelvic magnetic resonance imaging (MRI) for anal cancer and subsequently other societies such as the National Comprehensive Cancer Network followed suit with similar recommendations. Nevertheless, great variability exists from center to center and even within individual centers. Notably, this is in stark contrast to the imaging of the anatomically nearby rectal cancer. As participating team members for this malignancy, we embarked on a comprehensive literature review of anal cancer imaging to understand the relative merits of these new technologies which developed after computed tomography (CT), e.g., MRI and positron emission tomography/computed tomography (PET/CT). The results of this literature review helped to inform our next stage: questionnaire development regarding the imaging of anal cancer. Next, we distributed the questionnaire to members of the Society of Abdominal Radiology (SAR) Rectal and Anal Disease-Focused Panel, a group of abdominal radiologists with special interest, experience, and expertise in rectal and anal cancer, to provide expert radiologist opinion on the appropriate anal cancer imaging strategy. In our expert opinion survey, experts advocated the use of MRI in general (65% overall and 91-100% for primary staging clinical scenarios) and acknowledged the superiority of PET/CT for nodal assessment (52-56% agreement for using PET/CT in primary staging clinical scenarios compared to 30% for using MRI). We therefore support the use of MRI and PET and suggest further exploration of PET/MRI as an optimal combined evaluation. Our questionnaire responses emphasized the heterogeneity in imaging practice as performed at numerous academic cancer centers across the United States and underscore the need for further reconciliation and establishment of best imaging practice guidelines for optimized patient care in anal cancer.

Nodal drainage pathways in primary rectal cancer: anatomy of regional and distant nodal spread.

Nodal involvement is a significant prognostic factor in rectal cancer and difficult to assess preoperatively. An understanding of the patterns of nodal spread from different regions of the rectum can assist in this process and is essential for the purposes of surgical planning. In this article we define patterns of spread to mesenteric and pelvic sidewall nodal subgroups and discuss the importance of accurate anatomic localization of nodes for the purposes of staging and surgical planning.

MR staging of anal cancer: what the radiologist needs to know.

Anal canal cancer is a rare disease and squamous cell carcinoma is the most common histologic subtype. Traditionally, anal cancer is imaged with CT and PET/CT for purposes of TNM staging. With the increased popularity of MRI for rectal cancer evaluation, MRI has become increasingly utilized for local staging of anal cancer. In this review, we focus on the necessary information radiologists need to know to understand this rare and unique disease and to be familiar with staging of anal cancer on MRI.

Diagnosis and Diagnostic Imaging of Anal Canal Cancer.

Anal canal cancer is an uncommon malignancy but one that is often curable with optimal therapy. Owing to its unique location, histology, risk factors, and usual presentation, a careful diagnostic approach is warranted. This approach includes an excellent history and physical examination, including digital rectal examination, laboratory data, and comprehensive imaging. Anal cancer staging and formulation of a treatment plan depends on accurate imaging data. Modern radiographic techniques have improved staging quality and accuracy, and a thorough knowledge of anal anatomy is paramount to the optimal multidisciplinary treatment of this disease.

Variation in positron emission tomography use after colon cancer resection.

PURPOSE: Colon cancer surveillance guidelines do not routinely include positron emission tomography (PET) imaging; however, its use after surgical resection has been increasing. We evaluated the secular patterns of PET use after surgical resection of colon cancer among elderly patients and identified factors associated with its increasing use. PATIENTS AND METHODS: We used the SEER-linked Medicare database (July 2001 through December 2009) to establish a retrospective cohort of patients age ≥ 66 years who had undergone surgical resection for colon cancer. Postoperative PET use was assessed with the test for trends. Patient, tumor, and treatment characteristics were analyzed using univariable and multivariable logistic regression analyses. RESULTS: Of the 39,221 patients with colon cancer, 6,326 (16.1%) had undergone a PET scan within 2 years after surgery. The use rate steadily increased over time. The majority of PET scans had been performed within 2 months after surgery. Among patients who had undergone a PET scan, 3,644 (57.6%) had also undergone preoperative imaging, and 1,977 (54.3%) of these patients had undergone reimaging with PET within 2 months after surgery. Marriage, year of diagnosis, tumor stage, preoperative imaging, postoperative visit to a medical oncologist, and adjuvant chemotherapy were significantly associated with increased PET use. CONCLUSION: PET use after colon cancer resection is steadily increasing, and further study is needed to understand the clinical value and effectiveness of PET scans and the reasons for this departure from guideline-concordant care.

Local magnetic resonance imaging staging of rectal adenocarcinoma.

Successful multidisciplinary evaluation of potentially resectable rectal adenocarcinoma depends on high-resolution preoperative magnetic resonance imaging (MRI). Magnetic resonance imaging accurately identifies important risk factors of local recurrence and distant metastasis, thus facilitating enhanced preoperative prognostic stratification and treatment. When combined with appropriate neoadjuvant chemotherapy and total mesorectal excision, the treatment of rectal cancer has dramatically improved. Accurate local staging by MRI requires a robust combination of imaging sequences. Herein, we review MRI imaging and rectal anatomy related to the staging of rectal adenocarcinoma.

Intraoperative sonography during open partial nephrectomy for renal cell cancer: does it alter surgical management?

OBJECTIVE: The purpose of this study is to evaluate whether intraoperative ultrasound (IOUS) during open partial nephrectomy alters the surgical management for renal cell cancer (RCC). MATERIALS AND METHODS: One hundred ninety-eight consecutive patients undergoing IOUS during open partial nephrectomy for RCC were selected for retrospective review of clinical and imaging data. Patient age and sex, the local extent of the primary lesion, and the presence of additional lesions were recorded. Ultrasound findings were compared with preoperative CT or MRI to determine whether the IOUS findings changed surgical management. Summary statistics were performed to assess what percentage of patients with additional IOUS findings had a change in their surgical management. The Kaplan-Meier method was used to estimate 5-year overall survival (OS) and event-free survival (EFS) rates for all patients. Patients were followed for 9-12 years to assess survival and measure recurrence rates. RESULTS: Twenty-one of 198 patients (10.6%; 95% CI, 6.7-15.8%) had additional findings on IOUS not seen on preoperative imaging. As a result, surgery was modified in 15 of these 21 patients (71.4%; 95% CI, 47.8-88.7%). The 5-year OS rate was 81%, and the EFS rate was 76% for the whole group; most deaths were due to unrelated causes. There was no statistically significant difference in OS (p = 0.867) and EFS (p = 0.069) rates among patients who had a change of management because of additional lesions seen by IOUS. CONCLUSION: IOUS performed during open partial nephrectomy for resection of RCC shows additional findings compared with preoperative cross-sectional imaging that may alter surgical management.

Optimization of MR imaging for pretreatment evaluation of patients with endometrial and cervical cancer.

Endometrial and cervical cancer are the most common gynecologic malignancies in the world. Accurate staging of cervical and endometrial cancer is essential to determine the correct treatment approach. The current International Federation of Gynecology and Obstetrics (FIGO) staging system does not include modern imaging modalities. However, magnetic resonance (MR) imaging has proved to be the most accurate noninvasive modality for staging endometrial and cervical carcinomas and often helps with risk stratification and making treatment decisions. Multiparametric MR imaging is increasingly being used to evaluate the female pelvis, an approach that combines anatomic T2-weighted imaging with functional imaging (ie, dynamic contrast material-enhanced and diffusion-weighted imaging). MR imaging helps guide treatment decisions by depicting the depth of myometrial invasion and cervical stromal involvement in patients with endometrial cancer and tumor size and parametrial invasion in those with cervical cancer. However, its accuracy for local staging depends on technique and image quality, namely thin-section high-resolution multiplanar T2-weighted imaging with simple modifications, such as double oblique T2-weighting supplemented by diffusion weighting and contrast enhancement.

MR imaging of ectopic pregnancy with an emphasis on unusual implantation sites.

Ectopic pregnancy (EP) is a life-threatening condition and remains the leading cause of death in the first trimester of pregnancy, although the mortality rate has significantly decreased over the past few decades because of earlier diagnoses and great improvements in treatment. EP is most commonly located in the ampullary portion of the fallopian tube and rarely in unusual sites such as the interstitium, cervix, cesarean scar, anomalous rudimentary horn of the uterus and peritoneal abdominal cavity. MRI may confirm or give additional information to ultrasonography, which is the most user-dependent imaging modality. Magnetic resonance imaging can accurately localize the site of abnormal implantation. It could be helpful for EP patient treatment by distinguishing the ruptured and unruptured cases before methotrexate treatment. MRI is quite sensitive to blood and can identify the hemorrhage phase.

MR imaging for preoperative evaluation of primary rectal cancer: practical considerations.

High-resolution magnetic resonance (MR) imaging plays a pivotal role in the pretreatment assessment of primary rectal cancer. The success of this technique depends on obtaining good-quality high-resolution T2-weighted images of the primary tumor; the mesorectal fascia, peritoneal reflection, and other pelvic viscera; and superior rectal and pelvic sidewall lymph nodes. Although orthogonal axial high-resolution T2-weighted MR images are the cornerstone for the staging of primary rectal cancer, high-resolution sagittal and coronal images provide additional value, particularly in tumors that arise in a redundant tortuous rectum. Coronal high-resolution T2-weighted MR images also improve the assessment of nodal morphology, particularly for superior rectal and pelvic sidewall nodes, and of the relationship between advanced-stage tumors and adjacent pelvic structures. Rectal gel should be used in MR imaging examinations conducted for the staging of polypoid tumors, previously treated lesions, and small rectal tumors. However, it should not be used in examinations performed to stage large or low rectal tumors. Diffusion-weighted imaging is useful for identifying nodes and, occasionally, the primary tumor when the tumor is difficult to visualize with other sequences. Three-dimensional T2-weighted imaging provides multiplanar capability with a superior signal-to-noise ratio compared with two-dimensional T2-weighted imaging.

Pretreatment high-resolution rectal MRI and treatment response to neoadjuvant chemoradiation.

BACKGROUND: Use of rectal MRI evaluation of patients with rectal cancer for primary tumor staging and for identification for poor prognostic features is increasing. MR imaging permits precise delineation of tumor anatomy and assessment of mesorectal tumor penetration and radial margin risk. OBJECTIVE: The aim of this study was to evaluate the ability of pretreatment rectal MRI to classify tumor response to neoadjuvant chemoradiation. DESIGN: This study is a retrospective, consecutive cohort study and central review. SETTING: This study was conducted at a tertiary academic hospital. PATIENTS: Sixty-two consecutive patients with locally advanced (stage cII to cIII) rectal cancer who underwent rectal cancer protocol high-resolution MRI before surgery (December 2009 to March 2011) were included. MAIN OUTCOME MEASURES: The primary outcomes measured were the probability of good (ypT0-2N0) vs poor (≥ypT3N0) response as a function of mesorectal tumor depth, lymph node status, extramural vascular invasion, and grade assessed by uni- and multivariate logistic regression. RESULTS: Tumor response was good in 25 (40.3%) and poor in 37 (59.7%). Median interval from MRI to surgery was 7.9 weeks (interquartile range, 7.0-9.0). MRI tumor depth was <1 mm in 10 (16.9%), 1 to 5 mm in 30 (50.8%), and >5 mm in 21 (33.9%). Lymph node status was positive in 40 (61.5%), and vascular invasion was present in 16 (25.8%). Tumor response was associated with MRI tumor depth (p = 0.001), MRI lymph node status (p < 0.001) and vascular invasion (p = 0.009). Multivariate regression indicated >5 mm MRI tumor depth (OR = 0.08; 95% CI = 0.01-0.93; p = 0.04) and MRI lymph node positivity (OR = 0.12; 95% CI = 0.03-0.53; p = 0.005) were less likely to achieve a good response to neoadjuvant chemoradiotherapy. LIMITATIONS: Generalizability is uncertain in centers with limited experience with MRI staging for rectal cancer. CONCLUSION: MRI assessment of tumor depth and lymph node status in rectal cancer is associated to tumor response to neoadjuvant chemoradiotherapy. These factors should therefore be considered for stratification of patients for novel treatment strategies reliant on pathologic response to treatment or for the selection of poor-risk patients for intensified treatment regimens.

Quality initiatives: CT radiation dose reduction: how to implement change without sacrificing diagnostic quality.

The risks and benefits of using computed tomography (CT) as opposed to another imaging modality to accomplish a particular clinical goal should be weighed carefully. To accurately assess radiation risks and keep radiation doses as low as reasonably achievable, radiologists must be knowledgeable about the doses delivered during various types of CT studies performed at their institutions. The authors of this article propose a process improvement approach that includes the estimation of effective radiation dose levels, formulation of dose reduction goals, modification of acquisition protocols, assessment of effects on image quality, and implementation of changes necessary to ensure quality. A first step toward developing informed radiation dose reduction goals is to become familiar with the radiation dose values and radiation-associated health risks reported in the literature. Next, to determine the baseline dose values for a CT study at a particular institution, dose data can be collected from the CT scanners, interpreted, tabulated, and graphed. CT protocols can be modified to reduce overall effective dose by using techniques such as automated exposure control and iterative reconstruction, as well as by decreasing the number of scanning phases, increasing the section thickness, and adjusting the peak voltage (kVp setting), tube current-time product (milliampere-seconds), and pitch. Last, PDSA (plan, do, study, act) cycles can be established to detect and minimize negative effects of dose reduction methods on image quality.

MR imaging in the triage of pregnant patients with acute abdominal and pelvic pain.

PURPOSE: To retrospectively assess the performance of MR imaging in the evaluation and triage of pregnant patients presenting with acute abdominal or pelvic pain. METHOD AND MATERIALS: MRI studies of pregnant patients who were referred for acute abdominal pain between 2001 and 2007 were included. MR images were retrospectively reviewed and compared with surgical and pathologic findings and clinical follow-up data. Analysis of imaging findings included evaluation of the visceral organs, bowel and mesentery, appendix (for presence of appendicitis), ovaries (detection and adnexal masses were evaluated), focal inflammation, presence of abscesses, and any other abnormal findings. RESULTS: A total of 118 pregnant patients were included. MR findings were inconclusive in 2 patients and were positive for acute appendicitis in 11 patients (n = 9 confirmed by surgery, n = 2 improved without surgery). One patient with inconclusive MR had surgically confirmed appendicitis; the other patient with inconclusive MR had surgically confirmed adnexal torsion. Other surgical/interventional diagnoses suggested by MR imaging were adnexal torsion (n = 4), abscess (n = 4), acute cholecystitis (n = 1), and gastric volvulus (n = 1). Two patients with MR diagnosis of torsion improved without surgery. One patient with MR diagnosis of abscess had biliary cystadenoma at surgery. The rest of the MR diagnoses above were confirmed surgically or interventionally. MR imaging was normal in 67 patients and demonstrated medically treatable etiology in 28 patients: adnexal lesions (n = 9), urinary pathology (n = 6), cholelithiasis (n = 4), degenerating fibroid (n = 3), DVT (n = 2), hernia (n = 1), colitis (n = 1), thick terminal ileum (n = 1), rectus hematoma (n = 1). Three of these patients had negative surgical exploration and one had adnexal mass excision during pregnancy. Other patients were discharged with medical treatment. The sensitivity, specificity, accuracy, positive predictive values (ppv), and negative predictive values (npv) of MR imaging for acute appendicitis, and surgical/ interventional diagnoses were 90.0% vs. 88.9%, 98.1% vs. 95.0%, 97.5% vs. 94.1%, 81.8% vs. 76.2%, 99.1% vs. 97.9%, respectively. CONCLUSION: MR imaging is an excellent modality for diagnosis of acute appendicitis and exclusion of diseases requiring surgical/interventional treatment. Therefore MR imaging is useful for triage of pregnant patients with acute abdominal and pelvic pain.

Magnetic resonance imaging of cystic adnexal lesions during pregnancy.

Management of cystic adnexal lesions diagnosed during pregnancy is a challenging issue for obstetricians. The range of treatment options changes from immediate surgery to close follow-up. This pictorial essay illustrates the magnetic resonance imaging findings of various cystic adnexal lesions in pregnant patients. Magnetic resonance imaging may help in better characterization of some of the cystic adnexal lesions diagnosed during pregnancy without exposing the fetus to ionizing radiation.

Gadolinium-based contrast exposure, nephrogenic systemic fibrosis, and gadolinium detection in tissue.

OBJECTIVE: The objective of our study was to retrospectively review one institution's cases of nephrogenic systemic fibrosis (NSF), evaluate possible associated factors, determine the prevalence of NSF, and search for gadolinium in skin samples obtained from patients with NSF. MATERIALS AND METHODS: A retrospective review of our dermatopathology database from 1997 to 2007 was performed to search for patients with NSF. The records of patients with NSF were reviewed for factors suspected to be associated with NSF such as acidosis, low hemoglobin levels, low serum calcium levels, inflammatory conditions, serum antibodies, pharmaceutical erythropoietin, angiotensin-converting enzyme inhibitors, gadolinium-based contrast agents (GBCAs), renal failure, and dialysis. The biopsy samples from NSF patients and from control subjects were examined with energy-dispersive X-ray spectroscopy to detect gadolinium. Retrospective chart reviews of patients evaluated at our local dialysis center and our dermatology clinic were conducted to identify patients who underwent MRI, who had NSF managed exclusively by our tertiary referral centers, or both from 1997 to 2007. RESULTS: Seven cases of NSF were found in the dermatopathology database. Two of the seven patients were also followed up at our outpatient dialysis clinic. No other cases of NSF were discovered within the dialysis clinic's population exclusively followed within our institution. All seven dermatopathology database NSF patients developed symptoms of NSF after receiving GBCAs during renal failure and showed concomitant proinflammatory conditions. No other proposed risk factors were uniformly present in these NSF cases. All four NSF patients with chronic renal failure developed NSF after hemodialysis, with one patient dialyzed 12 hours after receiving a contrast dose. Gadodiamide was the only GBCA that all seven NSF patients received before symptom onset. Symptom onset was from 3 weeks to 18 months after GBCA exposure, with cumulative GBCA doses ranging from 0.16 to 0.43 mmol/kg. Gadolinium was detected in six of seven NSF patients' skin biopsies. Seven of eight random control specimens obtained from three healthy control subjects, three patients with renal insufficiency who had not been exposed to gadodiamide, and two patients without renal disease who had been exposed to gadodiamide were negative. Seventy-two dialysis clinic patients underwent 127 contrast-enhanced MR examinations from 1997 to 2007. Eighteen patients received gadopentetate, none of whom developed NSF. Sixty-three patients received gadodiamide, two of whom developed NSF (prevalence of NSF in patients exposed to GBCA, 2.8%; odds ratio, 0.82 [95% CI, 0.04-18.10]; likelihood ratio, 1.16 [95% CI, 1.06-1.26]). Nine patients received both contrast agents. CONCLUSION: An association with GBCAs in the development of NSF is suggested in the setting of renal insufficiency, but other factors seem to play a role. Dialysis did not prevent the development of NSF. Gadolinium was detected in skin samples from NSF patients.

Magnetic resonance imaging of the chest, abdomen, and pelvis in the evaluation of pregnant patients with neoplasms.

This article illustrates the magnetic resonance (MR) technique and MR imaging (MRI) findings of various neoplasms in chest, abdomen, and pelvis in pregnant patients. MRI can provide useful information about characterization and staging of maternal neoplasms without exposing the fetus to ionizing radiation and can be considered as a first-line cross sectional imaging method as an adjunct to ultrasonography.