Absence of tumor invasion into pelvic structures in locally recurrent rectal cancer: prediction with preoperative MR imaging

Dutch national guidelines for locally recurrent rectal cancer

Due to improvements in treatment for primary rectal cancer, the incidence of LRRC has decreased. However, 6-12% of patients will still develop a local recurrence. Treatment of patients with LRRC can be challenging, because of complex and heterogeneous disease presentation and scarce - often low-grade - data steering clinical decisions. Previous consensus guidelines have provided some direction regarding diagnosis and treatment, but no comprehensive guidelines encompassing all aspects of the clinical management of patients with LRRC are available to date. The treatment of LRRC requires a multidisciplinary approach and overarching expertise in all domains. This broad expertise is often limited to specific expert centres, with dedicated multidisciplinary teams treating LRRC. A comprehensive, narrative literature review was performed and used to develop the Dutch National Guideline for management of LRRC, in an attempt to guide decision making for clinicians, regarding the complete clinical pathway from diagnosis to surgery.

The Role of Pelvic Exenteration in Cervical Cancer: A Review of the Literature

Pelvic exenteration represents a radical procedure aimed at achieving complete tumor resection with negative margins. Although it is the only therapeutic option for some cases of advanced tumors, it is associated with several perioperative complications. We believe that careful patient selection is related to better oncologic outcomes and lower complication rates. The objectives of this review are to identify the most current indications for this intervention, suggest criteria for case selection, evaluate recommendations for perioperative care, and review oncologic outcomes and potential associated complications. To this end, an analysis of English language articles in PubMed was performed, searching for topics such as the indication for pelvic exenteration for recurrent gynecologic neoplasms selection of oncologic cases, the impact of tumor size and extent on oncologic outcomes, preoperative and postoperative surgical management, surgical complications, and outcomes of overall survival and recurrence-free survival.

Whole-body MRI with diffusion-weighted imaging as an adjunct to18 F-fluorodeoxyglucose positron emission tomography and CT in patients with suspected recurrent colorectal cancer

AIM

The aim was to explore how findings of whole-body MRI including diffusion-weighted imaging (DW-MRI) compared to the routine diagnostic workup with CT and/or 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in patients with suspected recurrent colorectal cancer (CRC).

METHOD

This was an exploratory retrospective analysis of 55 patients with a clinical suspicion of recurrent CRC who underwent DW-MRI following CT and/or FDG-PET/CT. Two readers in consensus interpreted all clinical imaging reports and converted each described lesion into a confidence score (1 = definitely benign to 5 = definitely malignant). DW-MRI findings were compared to the most recent previous CT or PET/CT. Any discrepant or additional DW-MRI findings were documented and compared with histology and/or clinical follow-up (if available).

RESULTS

Whole-body MRI including diffusion-weighted imaging (DW-MRI) resulted in discrepant/additional findings in 26/55 (47%) cases; 23/37 (62%) compared to previous CT and 3/18 (17%) compared to previous PET/CT. These included 10 cases where DW-MRI converted previously inconclusive CT (n = 8) or PET/CT (n = 2) findings into a conclusive diagnosis, one where it contradicted a previous CT diagnosis of recurrence, five where DW-MRI diagnosed recurrent disease not previously reported on CT and 10 cases where DW-MRI detected additional lesions compared to CT (n = 9) or PET/CT (n = 1). Eighty-eight per cent of cases with discrepant/additional findings concerned patients with recurrent/metachronous peritoneal metastases. In total, DW-MRI resulted in 42 discrepant/additional lesions; the DW-MRI diagnosis was correct in 76% of these lesions and incorrect (false positive) in 7%. In the remaining 17%, no standard of reference was available.

CONCLUSIONS

This explorative study suggests that DW-MRI may be of added value to patients with a clinical suspicion for recurrent CRC, in particular to identify patients with peritoneal metastases. DW-MRI mainly has potential as a 'problem-solver' in patients with inconclusive or negative findings on previous imaging (in particular CT) and to detect additional disease sites in patients already diagnosed with recurrent disease.

Beyond Total Mesorectal Excision (TME)-Results of MRI-Guided Multivisceral Resections in T4 Rectal Carcinoma and Local Recurrence

Rectal cancer invading adjacent organs (T4) and locally recurrent rectal cancer (LRRC) pose a special challenge for surgical resection. We investigate the diagnostic performance of MRI and the results that can be achieved with MRI-guided surgery. All consecutive patients who underwent MRI-based multivisceral resection for T4 rectal adenocarcinoma or LRRC between 2005 and 2019 were included. Pelvic MRI findings were reviewed according to a seven-compartment staging system and correlated with histopathology. Outcomes were investigated by comparing T4 tumors and LRRC with respect to cause-specific survival in uni- and multivariate analysis. We identified 48 patients with T4 tumors and 28 patients with LRRC. Overall, 529 compartments were assessed with an accuracy of 81.7%, a sensitivity of 88.6%, and a specificity of 79.2%. Understaging was as low as 3.0%, whereas overstaging was 15.3%. The median number of resected compartments was 3 (interquartile range 3-4) for T4 tumors and 4 (interquartile range 3-5) for LRRC (p = 0.017). In 93.8% of patients with T4 tumors, a histopathologically complete (R0(local)-) resection could be achieved compared to 57.1% in LRRC (p < 0.001). Five-year overall survival for patients with T4 tumors was 53.3% vs. 32.1% for LRRC (p = 0.085). R0-resection and M0-category emerged as independent prognostic factors, whereas the number of resected compartments was not associated with prognosis in multivariate analysis. MRI predicts compartment involvement with high accuracy and especially avoids understaging. Surgery based on MRI yields excellent loco-regional results for T4 tumors and good results for LRRC. The number of resected compartments is not independently associated with prognosis, but R0-resection remains the crucial surgical factor.

Local Recurrences in Rectal Cancer: MRI vs. CT

Rectal cancers are often considered a distinct disease from colon cancers as their survival and management are different. Particularly, the risk for local recurrence (LR) is greater than in colon cancer. There are many factors predisposing to LR such as postoperative histopathological features or the mesorectal plane of surgical resection. In addition, the pattern of LR in rectal cancer has a prognostic significance and an important role in the choice of operative approach and. Therefore, an optimal follow up based on imaging is critical in rectal cancer. The aim of this review is to analyse the risk and the pattern of local recurrences in rectal cancer and to provide an overview of the role of imaging in early detection of LRs. We performed a literature review of studies published on Web of Science and MEDLINE up to January 2023. We also reviewed the current guidelines of National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO). Although the timing and the modality of follow-up is not yet established, the guidelines usually recommend a time frame of 5 years post surgical resection of the rectum. Computed Tomography (CT) scans and/or Magnetic Resonance Imaging (MRI) are the main imaging techniques recommended in the follow-up of these patients. PET-CT is not recommended by guidelines during post-operative surveillance and it is generally used for problem solving.

Development of a consensus-based delineation guideline for locally recurrent rectal cancer

BACKGROUND AND PURPOSE

Neoadjuvant chemoradiotherapy (nCRT) is used in locally recurrent rectal cancer (LRRC) to increase chances of a radical surgical resection. Delineation in LRRC is hampered by complex disease presentation and limited clinical exposure. Within the PelvEx II trial, evaluating the benefit of chemotherapy preceding nCRT for LRRC, a delineation guideline was developed by an expert LRRC team.

MATERIALS AND METHODS

Eight radiation oncologists, from Dutch and Swedish expert centres, participated in two meetings, delineating GTV and CTV in six cases. Regions at-risk for re-recurrence or irradical resection were identified by eleven expert surgeons and one expert radiologist. Target volumes were evaluated multidisciplinary. Inter-observer variation was analysed.

RESULTS

Inter-observer variation in delineation of LRRC appeared large. Multidisciplinary evaluation per case is beneficial in determining target volumes. The following consensus regarding target volumes was reached. GTV should encompass all tumour, including extension into OAR if applicable. If the tumour is in fibrosis, GTV should encompass the entire fibrotic area. Only if tumour can clearly be distinguished from fibrosis, GTV may be reduced, as long as the entire fibrotic area is covered by the CTV. CTV is GTV with a 1 cm margin and should encompass all at-risk regions for irradical resection or re-recurrence. CTV should not be adjusted towards other organs. Multifocal recurrences should be encompassed in one CTV. Elective nodal delineation is only advised in radiotherapy-naïve patients.

CONCLUSION

This study provides a first consensus-based delineation guideline for LRRC. Analyses of re-recurrences is needed to understand disease behaviour and to optimize delineation guidelines accordingly.

Locally Recurrent Rectal Cancer According to a Standardized MRI Classification System: A Systematic Review of the Literature

(1) Background: The classification of locally recurrent rectal cancer (LRRC) is not currently standardized. The aim of this review was to evaluate pelvic LRRC according to the Beyond TME (BTME) classification system and to consider commonly associated primary tumour characteristics. (2) Methods: A systematic review of the literature prior to April 2020 was performed through electronic searches of the Science Citation Index Expanded, EMBASE, MEDLINE, and CENTRAL databases. The primary outcome was to assess the location and frequency of previously classified pelvic LRRC and translate this information into the BTME system. Secondary outcomes were assessing primary tumour characteristics. (3) Results: A total of 58 eligible studies classified 4558 sites of LRRC, most commonly found in the central compartment (18%), following anterior resection (44%), in patients with an 'advanced' primary tumour (63%) and following neoadjuvant radiotherapy (29%). Most patients also classified had a low rectal primary tumour. The lymph node status of the primary tumour leading to LRRC was comparable, with 52% node positive versus 48% node negative tumours. (4) Conclusions: This review evaluates the largest number of LRRCs to date using a single classification system. It has also highlighted the need for standardized reporting in order to optimise perioperative treatment planning.

Extended pelvic resection for gynecological malignancies: A review of out-of-the-box surgery

The term 'out-of-the-box surgery' in gynecologic oncology was recently coined to describe the resection of tumor growing out of the endopelvic cavity. In the specific case of pelvic sidewall involvement, a laterally extended pelvic resection may be required. As previously defined by Höckel, this resection requires the en bloc removal of structures including the pelvic sidewall muscles, bones, nerves, and/or major vessels. This complex radical procedure leads to tumor-free margins in more than 75% of the patients, with reliable functional results. The rate of recurrence and overall survival are directly correlated with clear resection margins. Progress in imaging, surgical techniques, and perioperative care currently offer the opportunity to attempt surgical curative resection in selected patients for whom palliative therapy was the only alternative. However, the procedure is associated with a high rate of major postoperative complications affecting up to 60% of patients. Multidisciplinary expert centers are the most likely to achieve this complex surgery with favorable oncological outcomes. The aim of this review is to summarize the key issues of out-of-the-box surgery in gynecologic cancer.

The importance of MRI for rectal cancer evaluation

Magnetic resonance imaging (MRI) has gained increasing importance in the management of rectal cancer over the last two decades. The role of MRI in patients with rectal cancer has expanded beyond the tumor-node-metastasis (TNM) system in both staging and restaging scenarios and has contributed to identifying "high" and "low" risk features that can be used to tailor and personalize patient treatment; for instance, selecting the patients for neoadjuvant chemoradiation (NCRT) before the total mesorectal excision (TME) surgery based on risk of recurrence. Among those features, the status of the circumferential resection margin (CRM), extramural vascular invasion (EMVI), and tumor deposits (TD) have stood out. Moreover, MRI also has played a role in surgical planning, especially when the tumor is located in the low rectum, when the relationship between tumor and the anal canal is important to choose the best surgical approach, and in cases of locally advanced or recurrent tumors invading adjacent pelvic organs that may require more complex surgeries such as pelvic exenteration. As approaches using organ preservation emerge, including transanal local excision and "watch-and-wait", MRI may help in the patient selection for those treatments, follow up, and detection of tumor regrowth. Additionally, potential MRI-based prognostic and predictive biomarkers, such as quantitative and semi-quantitative metrics derived from functional sequences like diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE), and radiomics, are under investigation. This review provides an overview of the current role of MRI in rectal cancer in staging and restaging and highlights the main areas under investigation and future perspectives.

Pelvic exenteration: Pre-, intra-, and post-operative considerations

This review outlines the role of pelvic exenteration (PE) in the management of certain locally-advanced primary and recurrent rectal cancers. PE has undergone significant evolution over the past decades. Advances in pre-, intra-, and post-operative care have been directed towards achieving the 'holy grail' of an R0 resection, which remains the most important predictor of survival, quality of life, morbidity, and cost effectiveness following PE. Patient selection for surgery is largely determined by assessment of resectability. Pelvic magnetic resonance imaging determines the extent of local disease, while positron emission tomography remains the most accurate tool for exclusion of distant metastases. PE in the setting of metastatic disease or with palliative intent remains controversial. The intra-operative approach is based on the anatomical division of the pelvis into five compartments (anterior, central, posterior, and two lateral). Within each compartment are various possible dissection planes which are elected depending on the extent of tumour involvement. Innovations in surgical technique have allowed 'higher and wider' dissection planes with resultant en bloc excision of major vessels, major nerves, and bone. Evidence of improved R0 resection and survival rates with these techniques justifies the radicality of these novel approaches. Post-operative care for PE patients is technically demanding with a substantial hospital resource burden. Unique considerations for PE patients include the 'empty pelvis syndrome', urological complications, and management of post-operative malnutrition. While undeniably a morbid procedure, quality of life largely returns to baseline at six months, and for long-term survivors is sustained for up to five years.

Multivisceral Resection of Advanced Pelvic Tumors: From Planning to Implementation

Pelvic exenteration involves radical multivisceral resection for locally advanced and recurrent pelvic tumors. Advances in tumor staging, oncological therapies, preoperative patient optimization, surgical techniques, and critical care medicine have permitted the safe expansion of pelvic exenterative surgery at specialist units. It is now understood that in carefully selected patients, 5-year survival can exceed 60% following pelvic exenteration, and that very low mortality figures and an optimum postexenteration quality of life are possible. In the present review, we provide a contemporary summary of the current state of the art in pelvic exenterative surgery following all key phases of the treatment pipeline from patient staging and tumor assessment, to treatment planning and surgery.

Multimodal CEA-Targeted Image-Guided Colorectal Cancer Surgery using 111In-Labeled SGM-101

PURPOSE

Intraoperative image guidance may aid in clinical decision-making during surgical treatment of colorectal cancer. We developed the dual-labeled carcinoembryonic antigen-targeting tracer, [¹¹¹In]In-DTPA-SGM-101, for pre- and intraoperative imaging of colorectal cancer. Subsequently, we investigated the tracer in preclinical biodistribution and multimodal image-guided surgery studies, and assessed the clinical feasibility on patient-derived colorectal cancer samples, paving the way for rapid clinical translation.

EXPERIMENTAL DESIGN

SGM-101 was conjugated with p-isothiocyanatobenzyl-diethylenetriaminepentaacetic acid (DTPA) and labeled with Indium-111 (¹¹¹In). The biodistribution of 3, 10, 30, and 100 μg [¹¹¹In]In-DTPA-SGM-101 was assessed in a dose escalation study in BALB/c nude mice with subcutaneous LS174T human colonic tumors, followed by a study to determine the optimal timepoint for imaging. Mice with intraperitoneal LS174T tumors underwent micro-SPECT/CT imaging and fluorescence image-guided resection. In a final translational experiment, we incubated freshly resected human tumor specimens with the tracer and assessed the tumor-to-adjacent tissue ratio of both signals.

RESULTS

The optimal protein dose of  [¹¹¹In]In-DTPA-SGM-101 was 30 μg (tumor-to-blood ratio, 5.8 ± 1.1) and the optimal timepoint for imaging was 72 hours after injection (tumor-to-blood ratio, 5.1 ± 1.0). In mice with intraperitoneal tumors, [¹¹¹In]In-DTPA-SGM-101 enabled preoperative SPECT/CT imaging and fluorescence image-guided resection. After incubation of human tumor samples, overall fluorescence and radiosignal intensities were higher in tumor areas compared with adjacent nontumor tissue (P < 0.001).

CONCLUSIONS

[¹¹¹In]In-DTPA-SGM-101 showed specific accumulation in colorectal tumors, and enabled micro-SPECT/CT imaging and fluorescence image-guided tumor resection. Thus, [¹¹¹In]In-DTPA-SGM-101 could be a valuable tool for preoperative SPECT/CT imaging and intraoperative radio-guided localization and fluorescence image-guided resection of colorectal cancer.

Radiomic Texture and Shape Descriptors of the Rectal Environment on Post-Chemoradiation T2-Weighted MRI are Associated with Pathologic Tumor Stage Regression in Rectal Cancers: A Retrospective, Multi-Institution Study

(1) Background: The relatively poor expert restaging accuracy of MRI in rectal cancer after neoadjuvant chemoradiation may be due to the difficulties in visual assessment of residual tumor on post-treatment MRI. In order to capture underlying tissue alterations and morphologic changes in rectal structures occurring due to the treatment, we hypothesized that radiomics texture and shape descriptors of the rectal environment (e.g., wall, lumen) on post-chemoradiation T2-weighted (T2w) MRI may be associated with tumor regression after neoadjuvant chemoradiation therapy (nCRT). (2) Methods: A total of 94 rectal cancer patients were retrospectively identified from three collaborating institutions, for whom a 1.5 or 3T T2w MRI was available after nCRT and prior to surgical resection. The rectal wall and the lumen were annotated by an expert radiologist on all MRIs, based on which 191 texture descriptors and 198 shape descriptors were extracted for each patient. (3) Results: Top-ranked features associated with pathologic tumor-stage regression were identified via cross-validation on a discovery set (n = 52, 1 institution) and evaluated via discriminant analysis in hold-out validation (n = 42, 2 institutions). The best performing features for distinguishing low (ypT0-2) and high (ypT3-4) pathologic tumor stages after nCRT comprised directional gradient texture expression and morphologic shape differences in the entire rectal wall and lumen. Not only were these radiomic features found to be resilient to variations in magnetic field strength and expert segmentations, a quadratic discriminant model combining them yielded consistent performance across multiple institutions (hold-out AUC of 0.73). (4) Conclusions: Radiomic texture and shape descriptors of the rectal wall from post-treatment T2w MRIs may be associated with low and high pathologic tumor stage after neoadjuvant chemoradiation therapy and generalized across variations between scanners and institutions.

Outcomes of extended radical resections for locally advanced and recurrent pelvic malignancy involving the aortoiliac axis

AIM

Currently, there is no clear consensus on the role of extended pelvic resections for locally advanced or recurrent disease involving major vascular structures. The aims of this study were to report the outcomes of consecutive patients undergoing extended resections for pelvic malignancy involving the aortoiliac axis.

METHODS

Prospective data were collected on patients having extended radical resections for locally advanced or recurrent pelvic malignancies, with aortoiliac axis involvement, requiring en bloc vascular resection and reconstruction, at a single institution between 2014 and 2018.

RESULTS

Eleven patients were included (median age 60 years; range 31-69 years; seven women). The majority required resection of both arterial and venous systems (n = 8), and the technique for vascular reconstruction was either interposition grafts or femoral-femoral crossover grafts. The median operative time was 510 min (range 330-960 min). Clear resection margins (R0) were achieved in nine patients. The median length of stay was 25 days (range 7-83 days). Seven patients did not suffer an early complication. There was one serious complication (Clavien-Dindo ≥ 3), an arterial graft occlusion secondary to thrombus in the immediate postoperative period, requiring a return to theatre and thrombectomy. The median length of follow-up in this study was 22 months (range 4-58 months).

CONCLUSION

This series demonstrates that en bloc major vascular resection and reconstruction can be performed safely and can achieve clear resection margins in selected patients with locally advanced or recurrent pelvic malignancy at specialist surgery centres.

The added value of pelvic surveillance by MRI during postoperative follow-up of rectal cancer, with a focus on abbreviated MRI

OBJECTIVES

To assess the added value of MRI over CT for the detection of pelvic recurrence during postoperative surveillance after rectal cancer surgery and to compare the diagnostic accuracy for pelvic recurrence achieved with abbreviated MRI (aMRI) with that of conventional enhanced MRI (cMRI).

METHODS

Patients who underwent rectal cancer surgery followed by MRI in addition to the standard CT follow-up protocol were evaluated retrospectively. Two readers independently scored images from CT, cMRI, and aMRI, which consisted of T2-weighted and diffusion-weighted imaging, to rate the likelihood of recurrence. Diagnostic accuracy and ROC curves were calculated. The patients were divided into two groups for risk-adapted surveillance according to risk of recurrence: high-risk (n = 157) and low-risk (n = 169) groups.

RESULTS

In total, 579 MRIs from 326 patients were assessed. A total of 48 pelvic recurrences occurred in 33 patients. The AUC in cMRI, aMRI, and CT were 0.98, 0.99, and 0.84, respectively. The difference in performance between CT and cMRI or aMRI for identifying recurrence was statistically significant (p < 0.001). Both cMRI and aMRI showed superior performance compared with CT in the high-risk group (p < 0.001), but this was not the case in the low-risk group (p = 0.13). Furthermore, the diagnostic accuracy of aMRI was similar to that of cMRI.

CONCLUSIONS

The addition of MRI to the postoperative surveillance protocol may result in an improvement in the detection of pelvic recurrence after rectal cancer surgery. For patients at high risk of recurrence, an aMRI surveillance may be justified to improve the diagnostic yield.

KEY POINTS

• The addition of MRI to the postoperative surveillance protocol improved the diagnostic yield in patients at a high risk of recurrence. • Abbreviated non-enhanced MRI with DWI allows detection of pelvic recurrence with a diagnostic accuracy that is similar to that of contrast-enhanced MRI (AUC, 0.99 and 0.98, respectively; p = 0.12). • Abbreviated MRI that is restricted to high spatial resolution structural imaging and diffusion-weighted imaging takes less time and can be carried out without the need for injection of a contrast agent.

Locally recurrent rectal cancer: what the radiologist should know

Despite advances in surgical techniques and chemoradiation therapy, recurrent rectal cancer remains a cause of morbidity and mortality. After successful treatment of rectal cancer, patients are typically enrolled in a surveillance strategy that includes imaging as studies have shown improved prognosis when recurrent rectal cancer is detected during imaging surveillance versus based on development of symptoms. Additionally, patients who experience a complete clinical response with chemoradiation therapy may elect to enroll in a "watch-and-wait" strategy that includes imaging surveillance rather than surgical resection. Factors that increase the likelihood of recurrence, patterns of recurrence, and the imaging appearances of recurrent rectal cancer are reviewed with a focus on CT, PET CT, and MR imaging.

Multiple mathematical models of diffusion-weighted magnetic resonance imaging combined with prognostic factors for assessing the response to neoadjuvant chemotherapy and radiation therapy in locally advanced rectal cancer

PURPOSE

To investigate whether the apparent diffusion coefficient (ADC), intravoxel incoherent motion (IVIM), and stretched exponential model (SEM) based on histogram analyses derived from the whole-tumor volume combined with prognostic factors can be used to assess the response to chemotherapy and radiation therapy (CRT) in locally advanced rectal cancer (LARC).

MATERIALS AND METHODS

This study included 60 patients with LARC who underwent diffusion-weighted imaging with 9b values (0-1000s/mm²) before CRT. Histograms derived from the whole-tumor volume were used to obtain the ADC, IVIM (D_slow, D_fast, and f), and SEM parameters (distributed diffusion coefficient (DDC) and α). The histogram metrics and prognostic factors before CRT were compared between pathological complete response (pCR) and non-pCR patients. The receiver operating characteristic (ROC) and the area under the ROC curve (AUC) were generated to analyze the histogram metrics and prognostic factors.

RESULTS

A significant difference was only found in the tumor volume between the pCR and non-pCR groups (p = 0.033, AUC = 0.740). The ADC mean, DDC median, and most of the histogram metrics were significantly lower in the pCR group than the non-pCR group (p = 0.000-0.025), and AUC was highest for the ADC mean (0.890). Only the D_slow median differed significantly between the two groups (p = 0.023, AUC = 0.721). However, the D_fast, f, and α histogram metrics did not differ significantly between the pCR and non-pCR groups. The AUC for the ADC mean combined with the tumor volume was 0.908, with a sensitivity of 100% and specificity of 81%. The inter-observer agreements were good or excellent for the ADC and SEM histogram parameters but generally fair for IVIM.

CONCLUSION

The whole-tumor ADC mean combined with the tumor volume was highly accurate for predicting pCR. The IVIM models were inferior to ADC and SEM at predicting pCR.

Coregistration of Preoperative MRI with Ex Vivo Mesorectal Pathology Specimens to Spatially Map Post-treatment Changes in Rectal Cancer Onto In Vivo Imaging: Preliminary Findings

RATIONALE AND OBJECTIVES

The objective of this study was to develop and quantitatively evaluate a radiology-pathology fusion method for spatially mapping tissue regions corresponding to different chemoradiation therapy-related effects from surgically excised whole-mount rectal cancer histopathology onto preoperative magnetic resonance imaging (MRI).

MATERIALS AND METHODS

This study included six subjects with rectal cancer treated with chemoradiation therapy who were then imaged with a 3-T T2-weighted MRI sequence, before undergoing mesorectal excision surgery. Excised rectal specimens were sectioned, stained, and digitized as two-dimensional (2D) whole-mount slides. Annotations of residual disease, ulceration, fibrosis, muscularis propria, mucosa, fat, inflammation, and pools of mucin were made by an expert pathologist on digitized slide images. An expert radiologist and pathologist jointly established corresponding 2D sections between MRI and pathology images, as well as identified a total of 10 corresponding landmarks per case (based on visually similar structures) on both modalities (five for driving registration and five for evaluating alignment). We spatially fused the in vivo MRI and ex vivo pathology images using landmark-based registration. This allowed us to spatially map detailed annotations from 2D pathology slides onto corresponding 2D MRI sections.

RESULTS

Quantitative assessment of coregistered pathology and MRI sections revealed excellent structural alignment, with an overall deviation of 1.50 ± 0.63 mm across five expert-selected anatomic landmarks (in-plane misalignment of two to three pixels at 0.67- to 1.00-mm spatial resolution). Moreover, the T2-weighted intensity distributions were distinctly different when comparing fibrotic tissue to perirectal fat (as expected), but showed a marked overlap when comparing fibrotic tissue and residual rectal cancer.

CONCLUSIONS

Our fusion methodology enabled successful and accurate localization of post-treatment effects on in vivo MRI.

Safety and effectiveness of SGM-101, a fluorescent antibody targeting carcinoembryonic antigen, for intraoperative detection of colorectal cancer: a dose-escalation pilot study

BACKGROUND

Tumour-targeted fluorescence imaging has the potential to advance current practice of oncological surgery by selectively highlighting malignant tissue during surgery. Carcinoembryonic antigen (CEA) is overexpressed in 90% of colorectal cancers and is a promising target for colorectal cancer imaging. We aimed to assess the tolerability of SGM-101, a fluorescent anti-CEA monoclonal antibody, and to investigate the feasibility to detect colorectal cancer with intraoperative fluorescence imaging.

METHODS

We did an open-label, pilot study in two medical centres in the Netherlands. In the dose-escalation cohort, we included patients (aged ≥18 years) with primary colorectal cancer with increased serum CEA concentrations (upper limit of normal of ≥3 ng/mL) since diagnosis, who were scheduled for open or laparoscopic tumour resection. In the expansion cohort, we included patients (aged ≥18 years) with recurrent or peritoneal metastases of colorectal cancer, with increasing serum concentrations of CEA since diagnosis, who were scheduled for open surgical resection. We did not mask patients, investigators, or anyone from the health-care team. We assigned patients using a 3 + 3 dose design to 5 mg, 7·5 mg, or 10 mg of SGM-101 in the dose-escalation cohort. In the expansion cohort, patients received a dose that was considered optimal at that moment of the study but not higher than the dose used in the dose-escalation cohort. SGM-101 was administered intravenously for 30 min to patients 2 or 4 days before surgery. Intraoperative imaging was done to identify near-infrared fluorescent lesions, which were resected and assessed for fluorescence. The primary outcome was tolerability and safety of SGM-101, assessed before administration and continued up to 12 h after dosing, on the day of surgery, the first postoperative day, and follow-up visits at the day of discharge and the first outpatient clinic visit. Secondary outcomes were effectiveness of SGM-101 for detection of colorectal cancer, assessed by tumour-to-background ratios (TBR); concordance between fluorescent signal and tumour status of resected tissue; and diagnostic accuracy in both cohorts. This trial is registered with the Nederlands Trial Register, number NTR5673, and ClinicalTrials.gov, number NCT02973672.

FINDINGS

Between January, 2016, and February, 2017, 26 patients (nine in the dose-escalation cohort and 17 in the expansion cohort) were included in this study. SGM-101 did not cause any treatment-related adverse events, although three possibly related mild adverse events were reported in three (33%) of nine patients in the dose-escalation cohort and five were reported in three (18%) of 17 patients in the expansion cohort. Five moderate adverse events were reported in three (18%) patients in the expansion cohort, but they were deemed unrelated to SGM-101. No changes in vital signs, electrocardiogram, or laboratory results were found after administration of the maximum dose of 10 mg of SGM-101 in both cohorts. A dose of 10 mg, administered 4 days before surgery, showed the highest TBR (mean TBR 6·10 [SD 0·42] in the dose-escalation cohort). In the expansion cohort, 19 (43%) of 43 lesions were detected using fluorescence imaging and were not clinically suspected before fluorescent detection, which changed the treatment strategy in six (35%) of 17 patients. Sensitivity was 98%, specificity was 62%, and accuracy of fluorescence intensity was 84% in the expansion cohort.

INTERPRETATION

This study presents the first clinical use of CEA-targeted detection of colorectal cancer and shows that SGM-101 is safe and can influence clinical decision making during the surgical procedure for patients with colorectal cancer.

FUNDING

Surgimab.

Preliminary results of a cohort study of induction chemotherapy-based treatment for locally recurrent rectal cancer

BACKGROUND

A significant number of patients treated for locally recurrent rectal cancer have local or systemic failure, especially after incomplete surgical resection. Neoadjuvant treatment regimens in patients who have already undergone preoperative (chemo)radiotherapy for the primary tumour are limited. The objective of the present study was to evaluate the influence of a neoadjuvant regimen incorporating induction chemotherapy (ICT) in patients with locally recurrent rectal cancer who had preoperative (chemo)radiotherapy for the primary cancer or an earlier local recurrence.

METHODS

Patients were treated with a sequential neoadjuvant regimen including three or four cycles of 5-fluorouracil and oxaliplatin-containing chemotherapy. When no progressive disease was found at evaluation, neoadjuvant treatment was continued with chemoradiation therapy (CRRT) using 30 Gy with concomitant capecitabine. If there was a response to ICT, the patient was advised to continue with systemic chemotherapy after CRRT as consolidation chemotherapy while waiting for resection. These patients were compared with patients who received CRRT alone in the same time interval.

RESULTS

Of 58 patients who had ICT, 32 (55 per cent) had surgery with clear resection margins, of whom ten (17 per cent) exhibited a pathological complete response (pCR). The remaining 26 patients had 23 R1 and three R2 resections. In 71 patients who received CRRT, a similar rate of R0 (35 patients) and R1 (36) resection was found (P = 0·506), but only three patients (4 per cent) had a pCR (P = 0·015).

CONCLUSION

The incorporation of ICT in neoadjuvant regimens for locally recurrent rectal cancer is a promising strategy.

Advances in surgical management for locally recurrent rectal cancer: How far have we come?

Locally recurrent rectal cancer (LRRC) is a complex disease with far-reaching implications for the patient. Until recently, research was limited regarding surgical techniques that can increase the ability to perform an en bloc resection with negative margins. This has changed in recent years and therefore outcomes for these patients have improved. Novel radical techniques and adjuncts allow for more radical resections thereby improving the chance of negative resection margins and outcomes. In the past contraindications to surgery included anterior involvement of the pubic bone, sacral invasions above the level of S2/S3 and lateral pelvic wall involvement. However, current data suggests that previously unresectable cases may now be feasible with novel techniques, surgical approaches and reconstructive surgery. The publications to date have only reported small patient pools with the research conducted by highly specialised units. Moreover, the short and long-term oncological outcomes are currently under review. Therefore although surgical options for LRRC have expanded significantly, one should balance the treatment choices available against the morbidity associated with the procedure and select the right patient for it.

Validation of MRI and Surgical Decision Making to Predict a Complete Resection in Pelvic Exenteration for Recurrent Rectal Cancer

BACKGROUND

The main predictor of long-term survival in patients with recurrent rectal cancer is surgical resection with a clear resection margin. MRI plays a role in patient selection and surgical planning.

OBJECTIVE

This study aimed to validate MRI in determining pelvic involvement by comparing MRI to histological outcomes, to assess the effect of MRI on surgical planning by comparing MRI findings with the surgical procedure, and to compare MRI anatomical involvement with resection outcome to assess if MRI can predict a clear resection margin.

DESIGN

Retrospective study reviewing prepelvic exenteration MRI and correlating organ, involving an MRI with pathological involvement and surgical outcomes.

SETTINGS

Single quaternary referral center with a special interest in pelvic exenteration.

PATIENTS

The patients included 40 men and 22 women with median age of 60 years who had locally recurrent rectal cancer.

MAIN OUTCOME MEASURES

The accuracy of MRI as measured using sensitivity and specificity by correlating MRI involvement with pathological involvement was the primary outcome measured.

RESULTS

Recurrence in the anterior and central compartments was identified with accuracy on MRI and was likely to be associated with clear resection margins. MRI was less accurate at determining pelvic sidewall involvement. Lateral recurrence, high sacral, and nerve involvement were more likely to be associated with a positive resection margin. Sensitivity and specificity for pelvic sidewall structures was 46% and 91%. Involvement of nerve roots (60%-69%) and the upper sacrum (80%) on MRI was more likely to predict a positive resection margin than involvement of major pelvic viscera (22%).

LIMITATIONS

This study was limited by its retrospective nature.

CONCLUSIONS

MRI findings can be used to help predict resection margin. Prospective work with MRI interpretation and close correlation and involvement by pathologists is needed to address imaging and surgical limitations at the pelvic sidewall and high posterior margin.

Magnetic resonance imaging of rectal cancer: staging and restaging evaluation

Magnetic resonance imaging is used to non-invasively stage and restage rectal adenocarcinomas. Accurate staging is important as the depth of tumor extension and the presence or absence of lymph node metastases determines if an individual will undergo preoperative neoadjuvant chemoradiation. Accurate description of tumor location is important for presurgical planning. The relationship of the tumor to the anal sphincter in addition to the depth of local invasion determines the surgical approach used for resection. High-resolution T2-weighted imaging is the primary sequence used for initial staging. The addition of diffusion-weighted imaging improves accuracy in the assessment of treatment response on restaging scans. Approximately 10%-30% of individuals will experience a complete pathologic response following chemoradiation with no residual viable tumor found in the resected specimen at histopathologic assessment. In some centers, individuals with no residual tumor visible on restaging MR who are thought to be at high operative risk are monitored with serial imaging and a "watch and wait" approach in lieu of resection. Normal rectal anatomy, MR technique utilized for staging and restaging scans, and TMN staging are reviewed. An overview of surgical techniques used for resection including newer, minimally invasive endoluminal techniques is included.

Impact of multimodal therapy in locally recurrent rectal cancer

BACKGROUND

The practice of salvaging recurrent rectal cancer has evolved. The aim of this study was to define the evolving salvage potential over time among patients with locally recurrent disease, and to identify durable determinants of long-term success.

METHODS

The study included consecutive patients with recurrent rectal cancer undergoing multimodal salvage with curative intent between 1988 and 2012. Predictors of long-term survival were defined by Cox regression analysis and compared over time. Re-recurrence and subsequent treatments were evaluated.

RESULTS

After multidisciplinary evaluation of 229 patients, salvage therapy with curative intent included preoperative chemotherapy and/or radiotherapy (73·4 per cent; with 41·3 per cent undergoing repeat pelvic irradiation), surgical salvage resection with or without intraoperative irradiation (36·2 per cent), followed by postoperative adjuvant chemotherapy (38·0 per cent). Multivisceral resection was undertaken in 47·2 per cent and bone resection in 29·7 per cent. The R0 resection rate was 80·3 per cent. After a median follow-up of 56·5 months, the 5-year overall survival rate was 50 per cent in 2005-2012, markedly increased from 32 per cent in 1988-1996 (P = 0·044). Long-term success was associated with R0 resection (P = 0·017) and lack of secondary failure (P = 0·003). Some 125 patients (54·6 per cent) developed further recurrence at a median of 19·4 months after salvage surgery. Repeat operative rescue was feasible in 21 of 48 patients with local re-recurrence alone and in 17 of 77 with distant re-recurrence, with a median survival of 19·8 months after further recurrence.

CONCLUSION

The long-term salvage potential for recurrent rectal cancer improved significantly over time, with the introduction of an individualized treatment algorithm of multimodal treatments and surgical salvage. Durable predictors of long-term success were R0 resection at salvage operation, avoidance of secondary failure, and feasibility of repeat rescue after re-recurrence.

Lateral pelvic compartment excision during pelvic exenteration

BACKGROUND

Involvement of the lateral compartment remains a relative or absolute contraindication to pelvic exenteration in most units. Initial experience with exenteration in the authors' unit produced a 21 per cent clear margin rate (R0), which improved to 53 per cent by adopting a novel technique for en bloc resection of the iliac vessels and other side-wall structures. The objective of this study was to report morbidity and oncological outcomes in consecutive exenterations involving the lateral compartment.

METHODS

Patients undergoing pelvic exenteration between 1994 and 2014 were eligible for review.

RESULTS

Two hundred consecutive patients who had en bloc resection of the lateral compartment were included. R0 resection was achieved in 66·5 per cent of 197 patients undergoing surgery for cancer and 68·9 per cent of planned curative resections. For patients with colorectal cancer, a clear resection margin was associated with a significant overall survival benefit (P = 0·030). Median overall and disease-free survival in this group was 41 and 27 months respectively. Overall 1-, 3- and 5-year survival rates were 86, 46 and 35 per cent respectively. No predictors of survival were identified on univariable analysis other than margin status and operative intent. Excision of the common or external iliac vessels or sciatic nerve did not confer a survival disadvantage.

CONCLUSION

The continuing evolution of radical pelvic exenteration techniques has seen an improvement in R0 margin status from 21 to 66·5 per cent over a 20-year interval by routine adoption of a more lateral anatomical plane. Five-year overall survival rates are comparable with those for more centrally based tumours.

Does gadolinium-based contrast material improve diagnostic accuracy of local invasion in rectal cancer MRI? A multireader study

OBJECTIVE. The purpose of this study was to compare reader accuracy and agreement on rectal MRI with and without gadolinium administration in the detection of T4 rectal cancer. MATERIALS AND METHODS. In this study, two radiologists and one fellow independently interpreted all posttreatment MRI studies for patients with locally advanced or recurrent rectal cancer using unenhanced images alone or combined with contrast-enhanced images, with a minimum interval of 4 weeks. Readers evaluated involvement of surrounding structures on a 5-point scale and were blinded to pathology and disease stage. Sensitivity, specificity, negative predictive value, positive predictive value, and AUC were calculated and kappa statistics were used to describe interreader agreement. RESULTS. Seventy-two patients (38 men and 34 women) with a mean age of 61 years (range, 32-86 years) were evaluated. Fifteen patients had 32 organs invaded. Global AUCs without and with gadolinium administration were 0.79 and 0.77, 0.91 and 0.86, and 0.83 and 0.78 for readers 1, 2, and 3, respectively. AUCs before and after gadolinium administration were similar. Kappa values before and after gadolinium administration for pairs of readers ranged from 0.5 to 0.7. CONCLUSION. On the basis of pathology as a reference standard, the use of gadolinium during rectal MRI did not significantly improve radiologists' agreement or ability to detect T4 disease.

Rectal cancer: a review

Rectal cancer is the second most common cancer in large intestine. The prevalence and the number of young patients diagnosed with rectal cancer have made it as one of the major health problems in the world. With regard to the improved access to and use of modern screening tools, a number of new cases are diagnosed each year. Considering the location of the rectum and its adjacent organs, management and treatment of rectal tumor is different from tumors located in other parts of the gastrointestinal tract or even the colon. In this article, we will review the current updates on rectal cancer including epidemiology, risk factors, clinical presentations, screening, and staging. Diagnostic methods and latest treatment modalities and approaches will also be discussed in detail.

Magnetic resonance imaging of the gut: a primer for the luminal gastroenterologist

Magnetic resonance imaging (MRI) is well established for imaging the solid organs of the abdomen and pelvis. In recent years it has been having an increasingly important role in the evaluation of the gastrointestinal (GI) tract. Fluoroscopy and abdominal computed tomography, the traditional mainstays of bowel imaging, remain valuable; however, the contemporary emphasis on decreasing patient radiation exposure is driving practice toward non-ionizing modalities such as MRI. The inherent dynamic properties of MRI, its superior tissue contrast, and cross-sectional capabilities offer additional advantages. Here we review, from esophagus to anus, techniques and indications for MRI of the GI lumen with an emphasis on the normal MRI appearance of the GI tract and commonly encountered pathology.

Value of diffusion-weighted and gadolinium-enhanced MRI for the diagnosis of pelvic recurrence from colorectal cancer

PURPOSE

To prospectively assess the added value of gadolinium-enhanced and diffusion-weighted (DWI) MRI for the diagnosis of pelvic recurrence from colorectal cancer (CRC).

MATERIALS AND METHODS

Fifty-two patients with suspected pelvic recurrence from CRC underwent pelvic MRI with T2-weighted ("T2"), gadolinium-enhanced fat-suppressed T1-weighted ("gadolinium") and DWI MR sequences. Three readers (senior radiologist: R1, two residents: R2, R3) scored the likelihood of recurrence on "T2," "T2 + DWI," and "T2 + Gadolinium."

RESULTS

Twenty-seven patients had 42 sites of pelvic recurrence. On "T2," R1 achieved AUC of .95, sensitivity 88.4%, specificity 95.2%. For R2, these figures were .89, 81.4%, 90.5%, for R3 .90, 83.7%, 76%. Both Gadolinium injection and DWI significantly improved AUCs for residents but not for the senior radiologist: up to .988 (R2, P = 0.006) and to .98 (R3, P = 0.01) with DWI and to .96 (R2, P = 0.04), .98 (R3, P = 0.01) after gadolinium. All readers achieved slightly better AUCs with "T2 + DWI" than with "T2+Gadolinium" but not significantly (P = 0.68, P = 0.11, P = 0.3; respectively).

CONCLUSION

For diagnosis of pelvic recurrence from CRC, both DWI and gadolinium-enhanced MRI significantly increase diagnostic performances compared with "T2" MRI for residents. DWI may be helpful in patients with contra-indications to intravenous administration of gadolinium.

Clinical, MRI, and PET-CT criteria used by surgeons to determine suitability for pelvic exenteration surgery for recurrent rectal cancers: a Delphi study

BACKGROUND

Surgical resection with clear margins is the major predictor of long-term survival in recurrent rectal cancer. The extent of pelvic exenteration surgery depends on many factors including clinical and radiological criteria.

OBJECTIVE

The aim of this study was to establish which clinical, MRI, and PET criteria were considered important by surgeons who perform pelvic exenteration surgery, when assessing a patient with recurrent rectal cancer for pelvic exenteration surgery.

DESIGN

A 2-stage Delphi study was conducted among an international panel of 36 colorectal surgeons recruited via a snowball-sampling method. Surgeons rated the importance of 99 clinical and radiological criteria by using a 9-point scale.

MAIN OUTCOME MEASURES

Consensus was attained when at least 85% of the panel rated criteria within 3 points.

RESULTS

Clinical factors suggestive of systemic disease, symptoms of advanced local recurrence such as pain, surgical fitness, and cognitive impairment were considered important by the panel when considering suitability for surgery. Agreement regarding the indication for surgery was reached for 20 radiological factors. Strong agreement was achieved for factors associated with tumor involvement in the axial and anterior compartments. For only 16 of these 20 radiological factors was there an agreement that a clear resection margin was likely to be achieved.

LIMITATIONS

Further rounds of Delphi may have yielded greater consensus.

CONCLUSION

This study has identified a set of criteria considered by experts to be important in evaluating patients' suitability for pelvic exenteration surgery. Evaluation of these criteria is required to determine their clinical utility in predicting a negative resection margin at pelvic exenteration surgery.

The value of 18F-FDG PET/CT in recurrent gynecologic malignancies prior to pelvic exenteration

OBJECTIVE

In patients undergoing pelvic exenteration for recurrent gynecological malignancies, we assessed the performance of [(18)F]-FDG PET/CT for delineating disease extent and evaluated the association between quantitative FDG uptake metrics (SUVmax, total lesion glycolysis [TLG] and metabolic tumor volume [MTV]) and progression-free survival (PFS) and overall survival (OS).

METHODS

Retrospective study of patients undergoing pelvic exenteration for gynecologic malignancies between January 2002 and November 2011 who had FDG PET/CT within 90days before surgery. Two readers (R1, R2) independently determined the presence of bladder, rectum, vagina, cervix and pelvic side wall invasion and measured SUVmax, TLG and MTV in each patient. Areas under the curve (AUCs), for detecting organ invasion were calculated. Kaplan-Meier graphs were used to determine associations between FDG uptake and PFS/OS. Inter-reader agreement was assessed.

RESULTS

33 patients (mean age 56years, range: 28-81) were included; primary sites of disease were the cervix (n=18), uterus (n=8) and vagina/vulva (n=7). AUCs for organ invasion ranged from 0.74 to 0.96. There was a significant association between FDG uptake metrics incorporating tumor volume (TLG and MTV) and OS (p≤0.001) as well as between MTV and PFS (p=0.001). No significant association was identified between SUVmax and OS/PFS (p=0.604/0.652). Inter-reader agreement for organ invasion was fair to substantial (k=0.36-0.74) and almost perfect for FDG quantification (ICC=0.97-0.99).

CONCLUSION

In patients undergoing pelvic exenteration for recurrent gynecological malignancies, (18)F-FDG PET/CT is useful for preoperative assessment of disease extent. Furthermore, quantitative metrics of FDG uptake incorporating MTV serve as predictive biomarkers of progression-free and overall survival in this population.

Interactions in the aetiology, presentation and management of synchronous and metachronous adenocarcinoma of the prostate and rectum

Adenocarcinoma of the prostate and rectum are common male pelvic cancers and may present synchronously or metachronously and, due to their anatomic proximity. The treatment of rectal or prostate cancer (in particular surgery and/or radiotherapy) may alter the presentation, incidence and management should a metachronous tumour develop. This review focuses on the interaction between prostatic and rectal cancer diagnosis and management. We have restricted the scope of this large topic to general considerations, management of rectal cancer after prostate cancer treatment and vice versa, management of synchronous disease and cancer follow-up issues.

Diagnostic accuracy and value of magnetic resonance imaging (MRI) in planning exenterative pelvic surgery for advanced colorectal cancer

PURPOSE

To assess the diagnostic accuracy of magnetic resonance imaging (MRI) in detecting colorectal tumour invasion according to seven intrapelvic compartments for planning exenterative pelvic surgery.

METHOD

Sixty-three consecutive patients underwent preoperative MRI planning for exenterative surgery, defined as operative excision beyond conventional mesenteric planes for locally advanced (n=23) and recurrent (n=41) pelvic colorectal cancer. The institutional research committee approved of the study and waived the need for a consent form as the images were retrospectively assessed. Two radiologists reported tumour invasion for each of seven anatomic surgical resection compartments, blinded to histopathology and the intraoperative findings. Sensitivity, specificity and predictive values were calculated for the seven intrapelvic compartments. Cox regression analysis was used to calculate the risk of death and recurrence. Overall interobserver agreement was assessed using Cohen's Kappa coefficient (k).

RESULTS

The sensitivity of MRI was ≥93.3% in all but the lateral compartment where it was 89.3%. Specificity for the posterior (82.2%) and anterior compartments below the peritoneal reflection (86.4%) was lower compared to the other compartments. Agreement between the two radiologists was found to be good or very good for all compartments (k>0.72). An MRI diagnosis of tumour invasion in the anterior compartment above the peritoneal reflection was associated with a poorer survival (p=0.012).

CONCLUSION

MRI is accurate in predicting the extent of colorectal tumour within the pelvis and therefore can be used to determine the type of surgery required for curative resection. It should always be used to stage patients with advanced colorectal pelvic cancer.

Surgical management of locally recurrent rectal cancer

Developments in chemotherapeutic strategies and surgical technique have led to improved loco regional control of rectal cancer and a decrease in recurrence rates over time. However, locally recurrent rectal cancer continues to present considerable technical challenges and results in significant morbidity and mortality. Surgery remains the only therapy with curative potential. Despite a hostile intra-operative environment, with meticulous pre-operative planning and judicious patient selection, safe surgery is feasible. The potential benefit of new techniques such as intra-operative radiotherapy and high intensity focussed ultrasonography has yet to be thoroughly investigated. The future lies in identification of predictors of recurrence, development of schematic clinical algorithms to allow standardised surgical technique and further research into genotyping platforms to allow individualisation of therapy. This review highlights important aspects of pre-operative planning, intra-operative tips and future strategies, focussing on a multimodal multidisciplinary approach.

Value of MRI and diffusion-weighted MRI for the diagnosis of locally recurrent rectal cancer

Objectives

To evaluate the accuracy of standard MRI, diffusion-weighted MRI (DWI) and fusion images for the diagnosis of locally recurrent rectal cancer in patients with a clinical suspicion of recurrence.

Methods

Forty-two patients with a clinical suspicion of recurrence underwent 1.5-T MRI consisting of standard T2-weighted FSE (3 planes) and an axial DWI (b0,500,1000). Two readers (R1,R2) independently scored the likelihood of recurrence; [1] on standard MRI, [2] on standard MRI+DWI, and [3] on T2-weighted+DWI fusion images.

Results

19/42 patients had a local recurrence. R1 achieved an area under the ROC-curve (AUC) of 0.99, sensitivity 100% and specificity 83% on standard MRI versus 0.98, 100% and 91% after addition of DWI (p = 0.78). For R2 these figures were 0.87, 84% and 74% on standard MRI and 0.91, 89% and 83% with DWI (p = 0.09). Fusion images did not significantly improve the performance. Interobserver agreement was κ0.69 for standard MRI, κ0.82 for standard MRI+DWI and κ0.84 for the fusion images.

Conclusions

MRI is accurate for the diagnosis of locally recurrent rectal cancer in patients with a clinical suspicion of recurrence. Addition of DWI does not significantly improve its performance. However, with DWI specificity and interobserver agreement increase. Fusion images do not improve accuracy.