Local staging of rectal cancer using combined pelvic phased-array and endorectal coil MRI

Progress of MRI in predicting the circumferential resection margin of rectal cancer: A narrative review

Rectal cancer (RC) is the third most frequently diagnosed cancer worldwide, and the status of its circumferential resection margin (CRM) is of paramount significance for treatment strategies and prognosis. CRM involvement is defined as tumor touching or within 1 mm from the outermost part of tumor or outer border of the mesorectal or lymph node deposits to the resection margin. The incidence of involved CRM varied from 5.4 % to 36 %, which may associate with an in consistent definition of CRM, the quality of surgeries, and the different examination modalities. Although T and N status are essential factors in determining whether a patient should receive neoadjuvant therapy before surgery, CRM status is a powerful predictor of local and distant recurrence as well as survival rate. This review explores the significance of CRM, the various assessment methods, and the role of magnetic resonance imaging (MRI) and artificial intelligence-based MRI in predicting CRM status. MRI showed potential advantage in predicting CRM status with a high sensitivity and specificity compared to computed tomography (CT). We also discuss MRI advancements in RC imaging, including conventional MRI with body coil, high-resolution MRI with phased-array coil, and endorectal MRI. Along with a discussion of artificial intelligence-based MRI techniques to predict the CRM status of RCs before and after treatments.

Progress in the diagnosis of lymph node metastasis in rectal cancer: a review

Historically, the chief focus of lymph node metastasis research has been molecular and clinical studies of a few essential pathways and genes. Recent years have seen a rapid accumulation of massive omics and imaging data catalyzed by the rapid development of advanced technologies. This rapid increase in data has driven improvements in the accuracy of diagnosis of lymph node metastasis, and its analysis further demands new methods and the opportunity to provide novel insights for basic research. In fact, the combination of omics data, imaging data, clinical medicine, and diagnostic methods has led to notable advances in our basic understanding and transformation of lymph node metastases in rectal cancer. Higher levels of integration will require a concerted effort among data scientists and clinicians. Herein, we review the current state and future challenges to advance the diagnosis of lymph node metastases in rectal cancer.

Contemporary Management of Locally Advanced and Recurrent Rectal Cancer: Views from the PelvEx Collaborative

Pelvic exenteration is a complex operation performed for locally advanced and recurrent pelvic cancers. The goal of surgery is to achieve clear margins, therefore identifying adjacent or involved organs, bone, muscle, nerves and/or vascular structures that may need resection. While these extensive resections are potentially curative, they can be associated with substantial morbidity. Recently, there has been a move to centralize care to specialized units, as this facilitates better multidisciplinary care input. Advancements in pelvic oncology and surgical innovation have redefined the boundaries of pelvic exenterative surgery. Combined with improved neoadjuvant therapies, advances in diagnostics, and better reconstructive techniques have provided quicker recovery and better quality of life outcomes, with improved survival This article provides highlights of the current management of advanced pelvic cancers in terms of surgical strategy and potential future developments.

Magnetic Resonance Imaging Evaluation of the Accuracy of Various Lymph Node Staging Criteria in Rectal Cancer: A Systematic Review and Meta-Analysis

Background

Magnetic resonance imaging (MRI)-based lymph node staging remains a significant challenge in the treatment of rectal cancer. Pretreatment evaluation of lymph node metastasis guides the formulation of treatment plans. This systematic review aimed to evaluate the diagnostic performance of MRI in lymph node staging using various morphological criteria.

Methods

A systematic search of the EMBASE, Medline, and Cochrane databases was performed. Original articles published between 2000 and January 2021 that used MRI for lymph node staging in rectal cancer were eligible. The included studies were assessed using the QUADAS-2 tool. A bivariate random-effects model was used to conduct a meta-analysis of diagnostic test accuracy.

Results

Thirty-seven studies were eligible for this meta-analysis. The pooled sensitivity, specificity, and diagnostic odds ratio of preoperative MRI for the lymph node stage were 0.73 (95% confidence interval [CI], 0.68–0.77), 0.74 (95% CI, 0.68–0.80), and 7.85 (95% CI, 5.78–10.66), respectively. Criteria for positive mesorectal lymph node metastasis included (A) a short-axis diameter of 5 mm, (B) morphological standard, including an irregular border and mixed-signal intensity within the lymph node, (C) a short-axis diameter of 5 mm with the morphological standard, (D) a short-axis diameter of 8 mm with the morphological standard, and (E) a short-axis diameter of 10 mm with the morphological standard. The pooled sensitivity/specificity for these criteria were 75%/64%, 81%/67%, 74%/79%, 72%/66%, and 62%/91%, respectively. There was no significant difference among the criteria in sensitivity/specificity. The area under the receiver operating characteristic (ROC) curve values of the fitted summary ROC indicated a diagnostic accuracy rate of 0.75–0.81.

Conclusion

MRI scans have minimal accuracy as a reference index for pretreatment staging of various lymph node staging criteria in rectal cancer. Multiple types of evidence should be used in clinical decision-making.

Diffusion tensor imaging of rectal carcinoma: Clinical evaluation and its correlation with histopathological findings

OBJECTIVE

This study sought to assess the feasibility of diffusion tensor imaging (DTI) to noninvasively evaluate histological grade and lymph node metastasis in patients with rectal carcinoma (RC).

METHODS

Thirty-seven consecutive patients with histologically confirmed RC were examined by 1.5-T MRI. DTI was performed using a single-shot echo-planar imaging sequence with b values of 0 and 1000 s/mm² and motion-probing gradients in nine noncollinear directions. Fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) maps were compared with histopathological findings.

RESULTS

The FA values (0.357 ± 0.047) of the RCs were significantly lower than those of the normal rectal wall, muscle, prostate, and uterus (P < 0.001 for all), while the AD, MD, and RD values (1.221 ± 0.131, 0.804 ± 0.075, and 0.667 ± 0.057 × 10^-3 mm²/s, respectively) were also significantly lower than their respective normal values (P < 0.001 for all). The FA, AD, MD, and RD values for RC additionally showed significant inverse correlations with histological grades (r = -0.781, r = -0.750, r = -0.718, and r = -0.682, respectively; P < 0.001 for all). Further, the FA (0.430 vs. 0.611), AD (1.246 vs. 1.608 × 10^-3 mm²/s), MD (0.776 vs. 1.036 × 10^-3 mm²/s), and RD (0.651 vs. 0.824 × 10^-3 mm²/s) (P < 0.001 for all) of the metastatic and nonmetastatic lymph nodes were significantly different.

CONCLUSIONS

DTI may be clinically useful for the noninvasive evaluation of histological grade and lymph node metastasis in patients with RC.

MRI-based EMVI positivity predicts systemic recurrence in rectal cancer patients with a good tumor response to chemoradiotherapy followed by surgery

BACKGROUND

This study aimed to determine the prognostic value of baseline magnetic resonance imaging-based extramural vascular invasion status (EMVI) among rectal cancer patients with a good tumor response to standard chemoradiotherapy followed by surgery.

METHODS

A total of 359 patients with ypT0-2/N0 disease from The Yonsei Multicenter Colorectal Cancer Electronic Database were retrospectively included between January 2000 and December 2014. Magnetic resonance images and medical records were reviewed to investigate risk factors for tumor recurrence.

RESULTS

When we compared patients without and with EMVI, significant differences were observed in the 5-year disease-free survival rate (DFS) (80.8% vs 57.8%, P = 0.005) and in the 5-year systemic recurrence-free survival rate (SRFS) (86.9% vs 64.3%, P = 0.007). In the multivariate analysis, both mrEMVI and APR independently predicted overall DFS (APR; HR 2.088, 95% CI: 1.082-4.031, P = 0.028, mrEMVI; HR: 2.729, 95% CI: 1.230-6.058, P = 0.014). mrEMVI was only independent prognostic factor for systemic recurrence with statistical significance (HR: 3.321, 95% CI: 1.185-9.309, P = 0.022).

CONCLUSION

Even in rectal cancer patients with a good response to chemoradiotherapy followed by curative surgery, extramural vascular invasion and APR may predict poor disease-free survival outcomes. Intensified treatment strategy should be considered.

Co-registration of MRI and ultrasound: accuracy of targeting based on radiology-pathology correlation

We reviewed the role of multiparametric magnetic resonance imaging (MP-MRI) and methods of MRI guided biopsy including in-bore, cognitive fusion, and software-based fusion. MP-MRI has been developed, optimized, and studied as a means of improving prostate cancer detection beyond the standard evaluation that utilizes digital rectal examinations and serum prostate specific antigen (PSA). MP-MRI has been proven to be an excellent diagnostic imaging modality that improves prostate cancer detection and risk stratification by guiding biopsy samples. The co-registration between MRI and ultrasound has allowed for software-based fusion which enables office-based biopsy procedures while still benefiting from the detailed prostate characterization of MRI. MP-MRI/ultrasound fusion guided biopsy has been studied in detail as this technology has been developed, tested, and validated in the past decade. The imaging to pathology correlation supporting the use of MP-MRI/ultrasound fusion is well documented in the literature. As the indication for the use of prostate MP-MRI becomes more widespread, it is important to continue to evaluate the correlation between imaging and pathologic findings.

Colon cancer presenting as pseudo-obstruction during pregnancy - A case report

The incidence of colorectal cancer in pregnancy is between 0.002 and 0.008%. Diagnosis is often delayed as symptoms of colorectal cancer can mimic as common complaints of pregnancy. We present the case of a 29-year-old with a history of chronic constipation who presented in the second trimester with abdominal pain, inability to tolerate anything orally and no bowel movement in more than three weeks. Non-contrast MRI at presentation failed to show an obstructing mass. Patient was treated conservatively for presumed pseudo-obstruction secondary to worsening constipation from chronic ondansetron use and pregnancy. After four days without clinical improvement, she had a colonoscopy that revealed a completely obstructing sigmoid mass, which biopsies confirmed was a primary colorectal adenocarcinoma. The patient underwent a total abdominal colectomy. She was referred to medical oncology and began adjuvant chemotherapy consisting of 5-fluorouracil, leucovorin and oxaloplatin four weeks post-operatively.

Current topics in the multimodality treatment of locally advanced rectal cancer

The multimodality approach to the treatment of locally advanced rectal cancer has evolved to include neoadjuvant radiotherapy with or without concurrent chemotherapy, total mesorectal excision and adjuvant fluoropyrimidine-based chemotherapy. Though this broad strategy has yielded improvements in local control compared with historical data, overall survival remains largely unchanged. Current investigations focus on improving patient selection through new imaging modalities, improving surgical techniques, incorporating more aggressive systemic treatment regimens and the selective use of radiation. Here, we review emerging data regarding newer staging techniques, neoadjuvant chemotherapy, optimal timing of surgery, selective use of radiation and nonoperative approaches to the management of locally advanced rectal cancers.

Prostate Radiotherapy in the Era of Advanced Imaging and Precision Medicine

Tremendous technological advancements in prostate radiotherapy have decreased treatment toxicity and improved clinical outcomes for men with prostate cancer. While these advances have allowed for significant treatment volume reduction and whole-organ dose escalation, further improvement in prostate radiotherapy has been limited by classic techniques for diagnosis and risk stratification. Developments in prostate imaging, image-guided targeted biopsy, next-generation gene expression profiling, and targeted molecular therapies now provide information to stratify patients and select treatments based on tumor biology. Image-guided targeted biopsy improves detection of clinically significant cases of prostate cancer and provides important information about the biological behavior of intraprostatic lesions which can further guide treatment decisions. We review the evolution of prostate magnetic resonance imaging (MRI) and MRI-ultrasound fusion-guided prostate biopsy. Recent advancements in radiation therapy including dose escalation, moderate and extreme hypofractionation, partial prostate radiation therapy, and finally dose escalation by simultaneous integrated boost are discussed. We also review next-generation sequencing and discuss developments in targeted molecular therapies. Last, we review ongoing clinical trials and future treatment paradigms that integrate targeted biopsy, molecular profiling and therapy, and prostate radiotherapy.

MRI Local Staging and Restaging in Rectal Cancer

Magnetic resonance imaging (MRI) with rectal protocol modification is a reliable staging modality which is rapidly replacing transrectal ultrasound for staging. The added information delivered by MRI includes wide circumferential radial margin compromise, distant lymph node metastasis in the pelvis, and level of sphincter compromise in the low rectum. As more information becomes available through ongoing studies, MRI may be able to contribute the decision to treat rectal cancer nonoperatively.

MRI in local staging of rectal cancer: an update

Preoperative imaging for staging of rectal cancer has become an important aspect of current approach to rectal cancer management, because it helps to select suitable patients for neoadjuvant chemoradiotherapy and determine the appropriate surgical technique. Imaging modalities such as endoscopic ultrasonography, computed tomography, and magnetic resonance imaging (MRI) play an important role in assessing the depth of tumor penetration, lymph node involvement, mesorectal fascia and anal sphincter invasion, and presence of distant metastatic diseases. Currently, there is no consensus on a preferred imaging technique for preoperative staging of rectal cancer. However, high-resolution phased-array MRI is recommended as a standard imaging modality for preoperative local staging of rectal cancer, with excellent soft tissue contrast, multiplanar capability, and absence of ionizing radiation. This review will mainly focus on the role of MRI in preoperative local staging of rectal cancer and discuss recent advancements in MRI technique such as diffusion-weighted imaging and dynamic contrast-enhanced MRI.

The multidisciplinary approach to the treatment of rectal cancer: 2015 update

The multidisciplinary approach to the management of rectal cancer continues to evolve with developments in surgery, radiation therapy as well as systemic chemotherapy. Refinement of surgical techniques to improve organ preservation, selective use of neoadjuvant (or adjuvant) therapies, improvements in staging modalities and emerging criteria for the selection of tailored therapies are some of the advancements made over the last three decades. In addition, neoadjuvant treatment alternatives, multimodality sequencing and adaptive therapies based on treatment response continue to be a subject of clinical investigation. The current article reviews the salient topics related to the multidisciplinary treatment of resectable rectal cancer.

Role of multiparametric magnetic resonance imaging in the diagnosis of prostate cancer

Prostate cancer is the most common solid-organ malignancy among American men. It is currently most commonly diagnosed on random systematic biopsies prompted by elevated serum PSA levels. Multi-parametric MRI (MP-MRI) of the prostate has emerged as an anatomic and functional imaging modality, which offers accurate detection, localization and staging of prostate cancer. Recently, MP-MRI has gained an increasing role in guiding biopsies to sites of abnormality and in monitoring patients on active surveillance. Here, we discuss the historical development, current role, and potential future directions of MP-MRI in the diagnosis of prostate cancer.

Current status of magnetic resonance imaging (MRI) and ultrasonography fusion software platforms for guidance of prostate biopsies

Prostate MRI is currently the best diagnostic imaging method for detecting PCa. Magnetic resonance imaging (MRI)/ultrasonography (US) fusion allows the sensitivity and specificity of MRI to be combined with the real-time capabilities of transrectal ultrasonography (TRUS). Multiple approaches and techniques exist for MRI/US fusion and include direct 'in bore' MRI biopsies, cognitive fusion, and MRI/US fusion via software-based image coregistration platforms.

ACR Appropriateness Criteria pretreatment staging of colorectal cancer

Because virtually all patients with colonic cancer will undergo some form of surgical therapy, the role of preoperative imaging is directed at determining the presence or absence of synchronous carcinomas or adenomas and local or distant metastases. In contrast, preoperative staging for rectal carcinoma has significant therapeutic implications and will direct the use of radiation therapy, surgical excision, or chemotherapy. CT of the chest, abdomen, and pelvis is recommended for the initial evaluation for the preoperative assessment of patients with colorectal carcinoma. Although the overall accuracy of CT varies directly with the stage of colorectal carcinoma, CT can accurately assess the presence of metastatic disease. MRI using endorectal coils can accurately assess the depth of bowel wall penetration of rectal carcinomas. Phased-array coils provide additional information about lymph node involvement. Adding diffusion-weighted imaging to conventional MRI yields better diagnostic accuracy than conventional MRI alone. Transrectal ultrasound can distinguish layers within the rectal wall and provides accurate assessment of the depth of tumor penetration and perirectal spread, and PET and PET/CT have been shown to alter therapy in almost one-third of patients with advanced primary rectal cancer. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

MRI in T staging of rectal cancer: How effective is it?

Background:

Rectal cancer constitutes about one-third of all gastrointestinal (GI) tract tumors. Because of the high recurrence rates (30%) in rectal cancer, it is vitally important to accurately stage these tumours preoperatively so that appropriate surgical resection can be undertaken. MRI is the ideal technique for the preoperative staging of these tumours.

Aim:

To determine the accuracy of local T staging of rectal cancer with MRI, using histopathological staging as the gold.

Materials and Methods:

Forty consecutive patients admitted with rectal cancer over a period of 18 months were included in this retrospective study. MRI scans were performed prior to surgery in all patients, on 1.5T scanners. Two radiologists, with a special interest in gastrointestinal imaging reported all images. Two dedicated histopathologists reported the histology slides. The accuracy of preoperative local MRI T staging was assessed by comparison with postoperative histopathological staging.

Results:

There was agreement between MRI and histopathology (TNM) staging in 12 patients (30%). The sensitivity and specificity of MRI for T staging was 89% and 67% respectively. The circumferential resection margin (CRM) status was accurately staged in 94.1% of the patients.

Conclusions:

Preoperative staging with MRI is sensitive in identifying CRM involvement, which is the main factor affecting the outcome of surgery.

Rectal cancer staging

Rectal cancer staging provides critical information concerning the extent of the disease. The information gained from staging is used to determine prognosis, to guide management, and to assess response to therapy. Accurate staging is essential for directing the multidisciplinary approach to therapy. This article focuses on the evolution of staging systems, the rational for staging, and current methods used to stage rectal cancer.

Colorectal Carcinoma: Local Tumor Staging and Assessment of Lymph Node Metastasis by High-Resolution MR Imaging in Surgical Specimens

Purpose. To assess the accuracy of high-resolution MR imaging as a means of evaluating mural invasion and lymph node metastasis by colorectal carcinoma in surgical specimens. Materials and Methods. High-resolution T1-weighted and T2-weighted MR images were obtained in 92 surgical specimens containing 96 colorectal carcinomas. Results. T2-weighted MR images clearly depicted the normal colorectal wall as consisting of seven layers. In 90 (94%) of the 96 carcinomas the depth of mural invasion depicted by MR imaging correlated well with the histopathologic stage. Nodal signal intensity on T2-weighted images (93%) and nodal border contour (93%) were more accurate than nodal size (89%) as indicators of lymph node metastasis, and MR imaging provided the highest accuracy (94%-96%) when they were combined. Conclusion. High-resolution MR imaging is a very accurate method for evaluating both mural invasion and lymph node metastasis by colorectal carcinoma in surgical specimens.

Preoperative staging of rectal cancer

Preoperative staging is now an essential factor in the multidisciplinary management of rectal cancer because tumor stage is the strongest predictive factor for recurrence. Preoperative staging of rectal cancer can be divided into either local or distant staging. Local staging incorporates the assessment of mural wall invasion, circumferential resection margin involvement, as well as the nodal status for metastasis. Distant staging assesses for evidence of metastatic disease. The aim of this review is to consider the indications and limitations of the current preoperative imaging modalities for rectal cancer staging including clinical examination, endorectal ultrasound, magnetic resonance imaging, computed tomography and positron emission tomography–computed tomography, with respect to local and distant disease.

Multidisciplinary treatment of resectable rectal cancer

This review identifies evidence that influences current practices in the multidisciplinary treatment and shapes future directions in the treatment of resectable rectal cancer. Recent advances in surgery, radiotherapy and systemic chemotherapy have provided measurable improvements in disease control, functional outcomes and quality of life for patients with rectal cancer. However, controversies remain regarding the optimum delivery of adjuvant therapies. Preoperative radiation either with or without concurrent chemotherapy demonstrates lower recurrence, with minimal survival benefit. Currently, the use of neoadjuvant standard fractionation chemoradiation versus short-course radiation without chemotherapy is controversial and under investigation. New combinations of chemotherapeutic agents and targeted therapies are also being evaluated. In addition, criteria for patient selection are being re-evaluated to determine the relative benefit of modern treatments, so that we may better tailor adjuvant therapy recommendations to be patient-specific. Recommendations for adjuvant treatments of rectal cancer are continuing to evolve; however, survival has been only marginally affected despite low incidence of local recurrence. Future trials should aim to address the role of adjuvant therapies utilizing new criteria, such as function, quality of life and impact on development of metastatic disease.

Magnetic resonance imaging of anorectal neoplasms

Among imaging techniques, magnetic resonance imaging (MRI) has evolved as the most robust technique for the detection, characterization, and staging of anorectal cancers. With its superior contrast resolution, multiplanar imaging capability, and nil radiation risk, it has become the standard preoperative imaging tool in rectal tumors. In this article we aim to outline the various types of anorectal cancers, highlight the complex anatomy of this region, and discuss the immensely useful role of MRI in the management of anorectal cancers. Existing limitations and future applications in this area will also be discussed. Because rectal adenocarcinomas constitute the majority of tumors in this region, we will be discussing the input of MRI in the management of this condition in greater detail. This will be followed by an overview of MRI in anal carcinoma and other less common anorectal neoplasms.

Magnetic resonance imaging in locoregional staging of rectal adenocarcinoma

A comprehensive overview of the current status of magnetic resonance imaging (MRI) in the locoregional assessment and management of rectal adenocarcinoma is presented. Staging systems for rectal cancer and treatment strategies in its management are discussed to give the reader the context that shapes MRI acquisition techniques and interpretation. Findings on MRI are detailed and their accuracy reviewed based on currently available evidence. Optimization of MRI acquisition and relevant pelvic anatomy are reviewed. A detailed description of our approach in interpreting MRI for locoregional staging of rectal cancer is given and future directions are also introduced.

Rectal villous tumours: MR features and correlation with TRUS in the preoperative evaluation

AIM

The aim of this study was to assess the clinical relevance of MR and transrectal ultrasonography (TRUS) imaging of rectal villous tumours to elucidate the correlation between imaging results and specific histopathological tumour features, such as tumour size (T) and lymph node involvement (N), in order to establish the better technique for the pre-surgical patient evaluation.

PATIENTS AND METHODS

23 cases of villous tumours of the rectum were studied with phased-array MR and TRUS. All patients underwent either surgical or endoscopic treatment. Final diagnosis was based on histopathological results. In particular, the following features were characterized by the imaging techniques mentioned above: lesion site, distance between lesion and ano-rectal junction, size, morphology and contrast enhancement of lesions, fluid layer around the lesion, alterations of the deep layers of the rectal wall, sphincter infiltration, presence or absence of mesorectal, iliac and obturatory lymphnode involvement.

RESULTS

Histology established muscular involvement in 7 cases (T2), perirectal fat infiltration in 1 case (T3); in the remaining 15 cases, staging was Tis-T1. In 17/23 cases (73.9%) the lesions were correctly staged with both imaging techniques, whereas in 5/23 cases (21.7%) the lesions were overstaged. No cases were understaged. TRUS concorded with histological exams in 17/23 cases (73.9%). 5/23 cases (21.7%) were overstaged and 1/23 (4%) was understaged. MR and TRUS were in accordance in 20/23 cases (86.9%).

DISCUSSION

Considering the frequent degeneration of villous tumours, correct preoperative identification and precise evaluation of these lesions, such as the detection of rectal wall invasion, is essential in deciding optimal treatment strategy. MRI and TRUS allow the identification of specific features of villous tumours and of malignant degeneration, allowing for a correct local disease staging.

Endorectal ultrasonography versus phased-array magnetic resonance imaging for preoperative staging of rectal cancer

AIM: To compare the diagnostic accuracy of pelvic phased-array magnetic resonance imaging (MRI) and endorectal ultrasonography (ERUS) in the preoperative staging of rectal carcinoma.

METHODS: Thirty-four patients (15 males, 19 females) with ages ranging between 29 and 75 who have biopsy proven rectal tumor underwent both MRI and ERUS examinations before surgery. All patients were evaluated to determine the diagnostic accuracy of depth of transmural tumor invasion and lymph node metastases. Imaging results were correlated with histopathological findings regarded as the gold standard and both modalities were compared in terms of predicting preoperative local staging of rectal carcinoma.

RESULTS: The pathological T stage of the tumors was: pT1 in 1 patient, pT2 in 9 patients, pT3 in 21 patients and pT4 in 3 patients. The pathological N stage of the tumors was: pN0 in 19 patients, pN1 in 9 patients and pN2 in 6 patients. The accuracy of T staging for MRI was 89.70% (27 out of 34). The sensitivity was 79.41% and the specificity was 93.14%. The accuracy of T staging for ERUS was 85.29% (24 out of 34). The sensitivity was 70.59% and the specificity was 90.20%. Detection of lymph node metastases using phased-array MRI gave an accuracy of 74.50% (21 out of 34). The sensitivity and specificity was found to be 61.76% and 80.88%, respectively. By using ERUS in the detection of lymph node metastases, an accuracy of 76.47% (18 out of 34) was obtained. The sensitivity and specificity were found to be 52.94% and 84.31%, respectively.

CONCLUSION: ERUS and phased-array MRI are complementary methods in the accurate preoperative staging of rectal cancer. In conclusion, we can state that phased-array MRI was observed to be slightly superior in determining the depth of transmural invasion (T stage) and has same value in detecting lymph node metastases (N stage) as compared to ERUS.

Transrectal ultrasonography and magnetic resonance imaging in the staging of rectal cancer. Effect of experience

OBJECTIVE

To evaluate the effect of experience on preoperative staging of rectal cancer using magnetic resonance imaging (MRI) and transrectal ultrasound (TRUS).

MATERIAL AND METHODS

From January 2002 to May 2006, 134 consecutive patients with biopsy-proven rectal cancer were examined with a 1.5-Tesla MRI unit and TRUS using a 6.5-MHz transducer. An experienced gastrointestinal radiologist (R1) or a general radiologist (R2) performed the evaluations. All patients (78 M, 56 F, mean age 69.1 years, range 38-89) were treated with surgery alone. The mean size of the tumour was 4.0 cm (range 1.1-7.5). A complete postoperative histopathological examination was used as the gold standard.

RESULTS

At pathology, 42 of 134 (31%) tumours were classified as T1-T2 and 92 (69%) were classified as T3-T4. The TRUS sensitivity in rectal tumour T-staging was 93% for R1 and 75% for R2 (p<0. 01); specificity was 83% for R1 and 46% for R2 (p<0.05). The MRI sensitivity in rectal tumour T-staging was 96% for R1 and 77% for R2 (p<0. 05); the specificity was 74% for R1 and 40% for R2 (p<0.05). There was no difference in the results of N-staging between R1 and R2 for either TRUS or MRI.

CONCLUSION

Reader experience had a statistically significant positive effect on the preoperative prediction of tumour involvement of the rectal wall. To obtain high-quality preoperative prediction of rectal cancer T-stage, it is suggested that preoperative TRUS and MRI staging should be supervised by an expert in the colorectal cancer team. In addition to this supervision, the person responsible for staging should be trained through a defined training programme.

The role of three-dimensional endoluminal ultrasound imaging in the evaluation of anorectal diseases: a review

BACKGROUND

The authors conducted a review of the available English literature to evaluate the advantages of three-dimensional ultrasound for assessing anorectal pathology, to provide a state-of-the-art approach, and to compare this technique with conventional endoluminal ultrasound and other imaging methods.

METHODS

All studies describing results obtained with three-dimensional ultrasound in the evaluation of anorectal pathologies, both alone and compared with other techniques, were selected.

RESULTS

Since 1996, 32 articles have been published. In tumor staging, specific data derived by three-dimensional reconstruction for the assessment of T invasion and nodal involvement were more accurate than endoluminal ultrasound and computed tomography. For evaluating perianal sepsis, the detection of secondary fistula tracts and fluid collections and the location of internal openings were superior to endoanal magnetic resonance imaging. In the evaluation of anal incontinence, the results for sphincter defects were similar to those obtained with endoanal magnetic resonance imaging.

CONCLUSION

Analysis of the literature confirmed that three-dimensional ultrasound is a valuable technique for assessing anorectal disorders, facilitating the interpretation of the images obtained, and providing additional data that in many cases have changed the operative approach.

Clinical advantages of 3.0 T MRI over 1.5 T

Since approval by the FDA in 2000, human MR imaging (MRI) at 3.0 T has been increasingly used in clinical practice. In spite of the potential technical challenges, a number of clinical advantages of 3.0 T MRI over 1.5 T have been identified in the recent years. This article reviews the benefits and the current knowledge of 3.0 T whole-body MRI from an evidence-based perspective and summarizes its clinical applications.

Colorectal carcinoma: in vitro evaluation with high-spatial-resolution 3D constructive interference in steady-state MR imaging

PURPOSE

To retrospectively assess the accuracy of high-spatial-resolution three-dimensional (3D) constructive interference in steady-state (CISS) magnetic resonance (MR) imaging in the evaluation of mural invasion of colorectal carcinoma by using prospectively obtained in vitro images, with histopathologic analysis as the reference standard.

MATERIALS AND METHODS

Institutional review board approval was obtained for the prospective and retrospective components of this study, with informed consent for the former and waiver of informed consent for the latter. Surgical specimens were obtained in 92 patients (61 men, 31 women; mean age, 65 years) and contained 96 colorectal carcinomas. Specimens were examined with a 1.5-T MR system and a 4-cm-diameter loop coil. High-spatial-resolution 3D CISS MR images were obtained with 80 x 80-mm field of view, 512 x 512 matrix, and 0.7-mm section thickness, which resulted in a 0.017-mm(3) voxel size. The 3D data sets were postprocessed with surface-rendering software to generate virtual MR endoscopic images. The 3D CISS MR images were compared with histopathologic findings, and virtual MR endoscopic images were compared with macroscopic findings at surgery. Statistical analysis was performed with Spearman rank correlation.

RESULTS

In 92 (96%) colorectal carcinomas, the depth of mural invasion depicted by 3D CISS MR imaging correlated well with the histopathologic stage, although the stage assigned with 3D CISS MR imaging was higher than that assigned with histopathologic analysis in four (4%) carcinomas (r = 0.976, P < .001). Sensitivity, specificity, and accuracy were 100%, 94%-96%, and 98%-100%, respectively. In 91 (95%) carcinomas, virtual MR endoscopy clearly depicted the macroscopic type of carcinoma, including gross configuration and tumor ulceration (r = 0.916, P < .001).

CONCLUSION

High-spatial-resolution 3D CISS MR imaging has high diagnostic accuracy in the in vitro evaluation of mural invasion and macroscopic features of colorectal carcinomas.

Effect of using endorectal coil in preoperative staging of rectal carcinomas by pelvic MR imaging

PURPOSE

To assess the accuracy of magnetic resonance imaging with pelvic phased-array and endorectal coils prospectively, and evaluate if endorectal coil provides any additional information to high resolution pelvic MR imaging in rectal carcinoma staging.

MATERIALS AND METHODS

Preoperative MRI of 25 patients with rectal carcinoma was performed with pelvic phased-array coil alone, and with both phased-array coil and endorectal coil placed. Staging was made by evaluating images obtained by using both coils prospectively, and correlated with histopathologic staging. The images were then assessed separately, and compared to each other retrospectively.

RESULTS

Two and 3 of the 5 histopathologically proved T1 tumors were staged correctly on MRI with pelvic phased-array coil alone and after the endorectal coil placement, respectively. Histopathologically identified five T2 tumors were staged correctly as T2 in 4 of the cases, 1 was understaged and 10 of 14 patients who had T3 tumor were staged as T3, 4 of them were understaged as T2 on both techniques. Specificity, sensitivity and accuracy rates for staging of T3 tumors were found as 71%, 100% and 84%, respectively, for each technique. Sensitivity and positive predictive value of N staging were both 88% on both techniques.

CONCLUSION

Pelvic MR imaging after the placement of endorectal coil in addition to the phase-array coil was not superior to the imaging with phased-array coil alone in T staging of rectal carcinomas and the latter achieved better visualization of the lymph nodes by means of larger field of view.

Preoperative assessment of rectal cancer stage: state of the art

Rectal cancer is one of the most common tumors worldwide; it accounts for approximately 25-30% of cancers arising in the large bowel. Owing to greater distribution of screening programs and better attention from both patients and General Practitioners to this disease, in recent years we have observed an increasing number of cases diagnosed in the early stages, with a consequent better prognosis. The improved 5-year survival is also partially due to better, and more accurate, diagnostic techniques and to more curative treatments. In this review, the authors analyze and discuss the more recent diagnostic techniques for an accurate preoperative staging of rectal cancer, highlighting each method's advantages and limits for their routine use in clinical practice.

Review of CT Angiography of Aorta

The most common imaging modality used for diagnosis of aortic disease is CT, followed by transesophageal echocardiography, MRI, and aortography. If multiple imaging is performed, the initial imaging technique most frequently employed is computerized tomography. During the past decade, computed tomographic angiography (CTA) has become a standard non-invasive imaging modality for the depiction of vascular anatomy and pathology. The quality and speed of CTA examinations have increased dramatically as CT technology has evolved from-channel spiral CT systems to multichannel (4-, 8-, 10- and 16-slice) spiral CT system. The quality and speed of CTA is superior to other imaging modalities, and it is also cheaper and less invasive. CTA of the aorta has proven to be superior in diagnostic accuracy to conventional arteriography in several applications.

Imaging the female pelvis at 3.0 T

Three-Tesla whole body imaging is rapidly becoming part of routine clinical practice. Although it is generally thought that pelvic imaging at 3.0 T will be beneficial because of increased signal to noise and greater spectral separation, adjustments in protocol and sequence parameters are necessary to optimize image quality. The question remains as to whether 3.0-T imaging will offer further benefits beyond 1.5 T in terms of lesion characterization and functional imaging. This article aims to address safety concerns and to illustrate the potential benefits and technical challenges of imaging the female pelvis at 3.0 T. Imaging protocols and sequence parameters for routine gynecologic indications are suggested, and potential clinical applications at 3.0 T are discussed such as magnetic resonance spectroscopy, perfusion, diffusion weighted imaging, and the use of alternate contrast agents.