Staging of rectal cancer: diagnostic potential of multiplanar reconstructions with MDCT

Diagnostic Performance of Rectal CT for Staging Rectal Cancer: Comparison with Rectal MRI and Histopathology

Purpose

To compare the diagnostic performance of rectal CT with that of high-resolution rectal MRI and histopathology in assessing rectal cancer.

Materials and Methods

Sixty-seven patients with rectal cancer who underwent rectal CT with rectal distension using sonographic gel and high-resolution MRI were enrolled in this study. The distance from the anal verge/anorectal junction, distance to the mesorectal fascia (MRF), extramural depth (EMD), extramesorectal lymph node (LN) involvement, extramural venous invasion (EMVI), and T/N stages in rectal CT/MRI were analyzed by two gastrointestinal radiologists. The CT findings of 20 patients who underwent radical surgery without concurrent chemoradiotherapy were compared using histopathology. Interclass correlations and kappa statistics were used.

Results

The distance from the anal verge/anorectal junction showed an excellent intraclass correlation between CT and MRI for both reviewers. For EMD, the distance to the MRF, presence of LNs, extramesorectal LN metastasis, EMVI, T stage, and intermodality kappa or weighted kappa values between CT and MRI showed excellent agreement. Among the 20 patients who underwent radical surgery, T staging, circumferential resection margin involvement, EMVI, and LN metastasis on rectal CT showed acceptable concordance rates with histopathology.

Conclusion

Dedicated rectal CT may be on par with rectal MRI in providing critical information to patients with rectal cancer.

Interventional gastroenterology in oncology

Cancer is one of the foremost health problems worldwide and is among the leading causes of death in the United States. Gastrointestinal tract cancers account for almost one third of the cancer-related mortality globally, making it one of the deadliest groups of cancers. Early diagnosis and prompt management are key to preventing cancer-related morbidity and mortality. With advancements in technology and endoscopic techniques, endoscopy has become the core in diagnosis and management of gastrointestinal tract cancers. In this extensive review, the authors discuss the role endoscopy plays in early detection, diagnosis, and management of esophageal, gastric, colorectal, pancreatic, ampullary, biliary tract, and small intestinal cancers.

CT imaging of peritoneal carcinomatosis with surgical correlation: a pictorial review

Cytoreductive surgery in combination with hyperthermic intraperitoneal chemotherapy has revolutionized the survival and the quality of life in selected patients with peritoneal carcinomatosis. Preoperative CT is important for the selection of patients that may benefit from cytoreductive surgery and is useful for surgical planning. There are several tasks for the radiologist during CT interpretation: to describe cancerous implants on a "site-by-site" basis in the peritoneum, ligaments, mesenteries and visceral surfaces, to analyze patterns of involvement and to estimate the disease burden. Knowledge of the correlation between the CT and the surgical findings enhances the understanding of the disease and facilitates the communication between radiologists and surgeons.

Colorectal cancer: Parametric evaluation of morphological, functional and molecular tomographic imaging

Colorectal cancer (CRC) represents one of the leading causes of tumor-related deaths worldwide. Among the various tools at physicians’ disposal for the diagnostic management of the disease, tomographic imaging (e.g., CT, MRI, and hybrid PET imaging) is considered essential. The qualitative and subjective evaluation of tomographic images is the main approach used to obtain valuable clinical information, although this strategy suffers from both intrinsic and operator-dependent limitations. More recently, advanced imaging techniques have been developed with the aim of overcoming these issues. Such techniques, such as diffusion-weighted MRI and perfusion imaging, were designed for the “in vivo” evaluation of specific biological tissue features in order to describe them in terms of quantitative parameters, which could answer questions difficult to address with conventional imaging alone (e.g., questions related to tissue characterization and prognosis). Furthermore, it has been observed that a large amount of numerical and statistical information is buried inside tomographic images, resulting in their invisibility during conventional assessment. This information can be extracted and represented in terms of quantitative parameters through different processes (e.g., texture analysis). Numerous researchers have focused their work on the significance of these quantitative imaging parameters for the management of CRC patients. In this review, we aimed to focus on evidence reported in the academic literature regarding the application of parametric imaging to the diagnosis, staging and prognosis of CRC while discussing future perspectives and present limitations. While the transition from purely anatomical to quantitative tomographic imaging appears achievable for CRC diagnostics, some essential milestones, such as scanning and analysis standardization and the definition of robust cut-off values, must be achieved before quantitative tomographic imaging can be incorporated into daily clinical practice.

The clinical application value of multi-slice spiral CT enhanced scans combined with multiplanar reformations images in preoperative T staging of rectal cancer

This study aims to evaluate the diagnostic accuracy and clinical application value of multi-slice spiral CT (MSCT) enhanced scans combined with multiplanar reformations (MPRs) images compared with postoperative pathological results in preoperative T staging of rectal cancer.One hundred sixty-eight consecutive patients with rectal cancer were admitted in our hospital between January 2013 and October 2018. Conventional MSCT plain scans, multi-phase dynamic contrast-enhanced scans, and MPRs were performed in all patients before surgical operation. The preoperative T staging of the rectal cancer lesions was evaluated using MSCT enhanced scans combined with MPRs, which was verified by postoperative pathological results. The diagnostic accuracy of MSCT enhanced scans combined with MPRs in evaluating T staging of the rectal cancer lesions were analyzed by χ test and Kappa test.Compared with postoperative pathology, T staging using MSCT enhanced scans combined with MPRs had overall accuracy of 85.7%. Consistency between MSCT enhanced scans combined with MPRs and postoperative pathological staging was effective for T staging (Kappa = 0.658, χ = 4.200, P = .122).Conventional MSCT enhanced scans combined with MPRs are simple and feasible. It is consistent with the pathological diagnosis of evaluating T staging in the rectal cancer lesions. It can provide reliable imaging evidence for the preoperative evaluation of primary rectal cancer, especially in patients with magnetic resonance imaging (MRI) contraindications, or in grass-roots hospitals due to lack of MRI equipment.

CT Staging to Triage Selection of Patients With Poor-Prognosis Rectal Cancer for Neoadjuvant Treatment

OBJECTIVE. The purpose of this study was to evaluate CT as a screening tool for determining high risk of local recurrence of rectal tumors in a scenario of limited MRI availability. MATERIALS AND METHODS. Data were retrospectively analyzed for 180 consecutively registered patients with rectal adenocarcinoma and no previous treatment who underwent baseline CT and MRI staging within 30 days of each other. Two radiologists independently reviewed CT and MR images. CT scans were interpreted in multiplanar reformation. High risk of local recurrence was based on the MRI reference standard: T3cd (more than 5 mm of mesorectal fat infiltration) or T4 disease, N2 nodal status, mesorectal fascia involvement, extramural venous invasion, or positive pelvic sidewall nodes. The performance of CT for determination of high risk of local tumor recurrence was evaluated. RESULTS. Among the 180 patients 128 (71%) met MRI criteria for high risk of local recurrence. CT sensitivity was 84.4% (108/128) and specificity was 78.8% (41/52). The positive predictive value (PPV) of any high-risk CT feature was 90.7% (108/119). When T status was considered, the sensitivity of CT was 75.2% (79/105), specificity was 90.7% (68/75), and PPV was 91.9% (79/86). When tumors within 5.0 cm of the anal verge were excluded, sensitivity was 89.5% (51/57), specificity was 85.7% (24/28), and PPV was 92.7% (51/55). Using CT for disease staging could reduce MRI use by 66%. CONCLUSION. Tumors at high risk of local recurrence can be identified with CT without baseline MRI. Use of CT rather than MRI could markedly reduce costs of baseline staging and shorten time to initiation of neoadjuvant treatment.

Diagnostic value of fourth-generation iterative reconstruction algorithm with low-dose CT protocol in assessment of mesorectal fascia invasion in rectal cancer: comparison with magnetic resonance

PURPOSE

The purpose of the article is to compare the diagnostic performance about radiation dose and image quality of low-dose CT with iterative reconstruction algorithm (iDose4) and standard-dose CT in the assessment of mesorectal fascia (MRF) invasion in rectal cancer patients.

MATERIALS AND METHODS

Ninety-one patients with biopsy-proven primary rectal adenocarcinoma underwent CT staging: 42 underwent low-dose CT, 49 underwent standard CT protocol. Low-dose contrast-enhanced MDCT scans were performed on a 256 (ICT, Philips) scanner using 120 kV, automated mAs modulation, iDose4 iterative reconstruction algorithm. Standard-dose MDCT scans were performed on the same scanner with 120 kV, 200-300 mAs. All patients underwent a standard lower abdomen MR study (on 1.5T magnet), including multiplanar sequences, considered as reference standard. Diagnostic accuracy of MRF assessment was determined on CT images for both CT protocols and compared with MRI images. Dose-length product (DLP) and CT dose index (CTDI) calculated for both groups were compared and statistically analyzed.

RESULTS

Low-dose protocol with iDose4 showed high diagnostic quality in assessment of MRF with significant reduction (23%; p = 0.0081) of radiation dose (DLP 2453.47) compared to standard-dose examination (DLP 3194.32).

CONCLUSIONS

Low-dose protocol combined with iDose4 reconstruction algorithm offers high-quality images, obtaining significant radiation dose reduction, useful in the evaluation of MRF involvement in rectal cancer patients.

Development and validation of a preoperative prediction model for colorectal cancer T-staging based on MDCT images and clinical information

Objectives

This study aimed to establish and evaluate the efficacy of a prediction model for colorectal cancer T-staging.

Results

T-staging was positively correlated with the level of carcinoembryonic antigen (CEA), expression of carbohydrate antigen 19-9 (CA19-9), wall deformity, blurred outer edges, fat infiltration, infiltration into the surrounding tissue, tumor size and wall thickness. Age, location, enhancement rate and enhancement homogeneity were negatively correlated with T-staging. The predictive results of the model were consistent with the pathological gold standard, and the kappa value was 0.805. The total accuracy of staging improved from 51.04% to 86.98% with the proposed model.

Materials and Methods

The clinical, imaging and pathological data of 611 patients with colorectal cancer (419 patients in the training group and 192 patients in the validation group) were collected. A spearman correlation analysis was used to validate the relationship among these factors and pathological T-staging. A prediction model was trained with the random forest algorithm. T staging of the patients in the validation group was predicted by both prediction model and traditional method. The consistency, accuracy, sensitivity, specificity and area under the curve (AUC) were used to compare the efficacy of the two methods.

Conclusions

The newly established comprehensive model can improve the predictive efficiency of preoperative colorectal cancer T-staging.

Accuracy of Multi-Slice Spiral Computed Tomography for Preoperative Tumor Node Metastasis (TNM) Staging of Colorectal Carcinoma

Background

With the advances in imaging technologies, multi-slice spiral computed tomography (MSCT) has demonstrated superiority in the diagnosis and staging of colorectal carcinoma. In the current study, preoperative TNM staging of colorectal carcinoma by using MSCT was conducted and compared with the corresponding postoperative pathological examination findings, in order to evaluate the accuracy of preoperative MSCT for TNM staging.

Material/Methods

Combinations of biphasic or triphasic enhanced-phase MSCT scans were obtained for 76 patients with colorectal carcinoma, and the TNM stage was determined based on imaging reconstruction from various angles and perspectives to display the size, location, and affected range of tumors. The preoperative TNM stage was compared with the postoperative pathological stage, and the consistency between the 2 methods was tested by the κ test using SPSS 17.0 software.

Results

Among the different combinations of enhanced-phase MSCT scanning, triphasic MSCT imaging, comprising the arterial, portal venous, and delayed phases, showed the highest accuracy rates, at 81.6% (62/76), 82.89% (63/76), and 96.1% (73/76) for T, N, and M staging, respectively, with κ values of 0.72, 0.65, and 0.56, respectively, indicating consistency with the postoperative pathological staging.

Conclusions

Combined MSCT scanning comprising the arterial phase, portal venous phase, and delayed phase showed satisfying consistency with the postoperative pathological analysis results for TNM staging of colorectal carcinoma. Thus, MSCT is an important clinical value for improving the accuracy of TNM staging and for planning the appropriate colorectal cancer treatment.

Evaluating rectal tumor staging with magnetic resonance imaging, computed tomography, and endoluminal ultrasound: A meta-analysis

BACKGROUND

Magnetic resonance imaging (MRI), endoluminal ultrasound (EUS), and computed tomography (CT) are commonly used imaging tools to evaluate rectal tumor staging, but there was no recent meta-analysis to define the present role of the 3 tools. Here, we proposed to systematically compare the accuracy of the 3 imaging tools for rectal tumor staging.

METHODS

We systematically searched diagnostic accuracy studies of MRI, CT, or EUS on rectal cancer staging, written in English or Chinese, published between January 1, 2003 and Dec 31, 2015 from database of PubMed, EMBASE, and Cochrane Library. The reference standards should be pathological findings. Hierarchical regression model was used for producing summary receiver operating characteristic (SROC) curves and calculating diagnostic accuracy data including sensitivity, specificity, and diagnostic odds ratio for the 3 imaging tools. Investigation of sample size, quality items and resolution, and magnetic field strength on heterogeneity was detected by using subgroup analysis and SROC regression.

RESULTS

This analysis included 89 studies. MRI, CT, and EUS yielded similar diagnostic accuracy. Better performance was observed with high-resolution MRI and 3.0-T MRI (P = 0.01 and 0.04, respectively). EUS showed lower diagnostic accuracy after preoperative therapies (P = 0.03).

CONCLUSION

MRI, CT, and EUS have comparable accuracy for rectal tumor staging. High-resolution MRI and 3.0-T MRI can produce better staging results and were recommended. EUS is not suitable for rectal tumor staging for its significantly decreased accuracy.

Rectal cancer staging: Multidetector-row computed tomography diagnostic accuracy in assessment of mesorectal fascia invasion

AIM: To assess the diagnostic accuracy of multidetector-row computed tomography (MDCT) as compared with conventional magnetic resonance imaging (MRI), in identifying mesorectal fascia (MRF) invasion in rectal cancer patients.

METHODS: Ninety-one patients with biopsy proven rectal adenocarcinoma referred for thoracic and abdominal CT staging were enrolled in this study. The contrast-enhanced MDCT scans were performed on a 256 row scanner (ICT, Philips) with the following acquisition parameters: tube voltage 120 KV, tube current 150-300 mAs. Imaging data were reviewed as axial and as multiplanar reconstructions (MPRs) images along the rectal tumor axis. MRI study, performed on 1.5 T with dedicated phased array multicoil, included multiplanar T2 and axial T1 sequences and diffusion weighted images (DWI). Axial and MPR CT images independently were compared to MRI and MRF involvement was determined. Diagnostic accuracy of both modalities was compared and statistically analyzed.

RESULTS: According to MRI, the MRF was involved in 51 patients and not involved in 40 patients. DWI allowed to recognize the tumor as a focal mass with high signal intensity on high b-value images, compared with the signal of the normal adjacent rectal wall or with the lower tissue signal intensity background. The number of patients correctly staged by the native axial CT images was 71 out of 91 (41 with involved MRF; 30 with not involved MRF), while by using the MPR 80 patients were correctly staged (45 with involved MRF; 35 with not involved MRF). Local tumor staging suggested by MDCT agreed with those of MRI, obtaining for CT axial images sensitivity and specificity of 80.4% and 75%, positive predictive value (PPV) 80.4%, negative predictive value (NPV) 75% and accuracy 78%; while performing MPR the sensitivity and specificity increased to 88% and 87.5%, PPV was 90%, NPV 85.36% and accuracy 88%. MPR images showed higher diagnostic accuracy, in terms of MRF involvement, than native axial images, as compared to the reference magnetic resonance images. The difference in accuracy was statistically significant (P = 0.02).

CONCLUSION: New generation CT scanner, using high resolution MPR images, represents a reliable diagnostic tool in assessment of loco-regional and whole body staging of advanced rectal cancer, especially in patients with MRI contraindications.

Computed tomography and magnetic resonance imaging evaluation of lymph node metastasis in early colorectal cancer

AIM: To assess the role of computed tomography (CT) and magnetic resonance imaging (MRI) and establish imaging criteria of lymph node metastasis in early colorectal cancer.

METHODS: One hundred and sixty patients with early colorectal cancer were evaluated for tumor location, clinical history of polypectomy, depth of tumor invasion, and lymph node metastasis. Two radiologists assessed preoperative CT and/or MRI for the primary tumor site detectability, the presence or absence of regional lymph node, and the size of the largest lymph node. Demographic, imaging, and pathologic findings were compared between the two groups of patients based on pathologic lymph node metastasis and optimal size criterion was obtained.

RESULTS: The locations of tumor were ascending, transverse, descending, sigmoid colon, and rectum. One hundred and sixty early colorectal cancers were classified into 3 groups based on the pathological depth of tumor invasion; mucosa, submucosa, and depth unavailable. A total of 20 (12.5%) cancers with submucosal invasion showed lymph node metastasis. Lymph nodes were detected on CT or MRI in 53 patients. The detection rate and size of lymph nodes were significantly higher (P = 0.000, P = 0.044, respectively) in patients with pathologic nodal metastasis than in patients without nodal metastasis. Receiver operating curve analysis showed that a cut-off value of 4.1 mm is optimal with a sensitivity of 78.6% and specificity of 75%.

CONCLUSION: The short diameter size criterion of ≥ 4.1 mm for metastatic lymph nodes was optimal for nodal staging in early colorectal cancer.

Multimodal imaging evaluation in staging of rectal cancer

Rectal cancer is a common cancer and a major cause of mortality in Western countries. Accurate staging is essential for determining the optimal treatment strategies and planning appropriate surgical procedures to control rectal cancer. Endorectal ultrasonography (EUS) is suitable for assessing the extent of tumor invasion, particularly in early-stage or superficial rectal cancer cases. In advanced cases with distant metastases, computed tomography (CT) is the primary approach used to evaluate the disease. Magnetic resonance imaging (MRI) is often used to assess preoperative staging and the circumferential resection margin involvement, which assists in evaluating a patient’s risk of recurrence and their optimal therapeutic strategy. Positron emission tomography (PET)-CT may be useful in detecting occult synchronous tumors or metastases at the time of initial presentation. Restaging after neoadjuvant chemoradiotherapy (CRT) remains a challenge with all modalities because it is difficult to reliably differentiate between the tumor mass and other radiation-induced changes in the images. EUS does not appear to have a useful role in post-therapeutic response assessments. Although CT is most commonly used to evaluate treatment responses, its utility for identifying and following-up metastatic lesions is limited. Preoperative high-resolution MRI in combination with diffusion-weighted imaging, and/or PET-CT could provide valuable prognostic information for rectal cancer patients with locally advanced disease receiving preoperative CRT. Based on these results, we conclude that a combination of multimodal imaging methods should be used to precisely assess the restaging of rectal cancer following CRT.

Preoperative staging of colorectal cancer: accuracy of single portal venous phase multidetector computed tomography

In this study, we aimed to investigate the accuracy of single portal venous phase multidetector computed tomography (MDCT) in preoperative staging of colorectal cancer. MDCT, surgery, and pathological results of 159 patients with pathologically proven colorectal adenocarcinoma were evaluated retrospectively. In T staging, the accuracy was 96% for ≤ T2 tumors, 92% for T3 tumors, and 96% for T4 tumors. In N staging, the accuracy was 68% for N0 tumors, 74% for N1 tumors, and 71% for N2 tumors. In conclusion, the accuracy of single portal venous phase MDCT is reasonably high in T staging, but it is not sufficiently high enough in N staging.

Evaluation of the growth pattern of carcinoma of colon and rectum by MDCT

BACKGROUND

Colorectal cancer is a leading cause of cancer morbidity and mortality worldwide. Knowledge of colorectal cancer tumor growth is of importance for basic understanding of tumor biology and for the clinical handling of the disease.

PURPOSE

To conduct a retrospective evaluation of the growth pattern of colorectal cancer by multidetector computed tomography (MDCT).

MATERIAL AND METHODS

Pathologically proven adenocarcinomas of the colon and rectum in 44 patients were examined by MDCT on at least two separate occasions with an interval of >1 month in patients not receiving therapy. Maximal longitudinal diameters, wall thicknesses, and volume changes, as determined by serial CT scans, were used in calculation of growth rates.

RESULTS

Mean longitudinal diameters of tumors at initial and follow-up investigations were 3.8 cm (1.0-9.1 cm) and 5.4 cm (2.5-12.2 cm), respectively. The mean growth rate of longitudinal tumor diameter was 3.4 cm/year (0-13.8 cm/year). Mean axial wall thicknesses at initial and follow-up investigations were 1.4 cm (0.6-6.6 cm) and 1.9 cm (0.8-6.8 cm), respectively. Mean growth rate of tumor axial wall thickness was 1.0 cm/year (0-3.1 cm/year). Mean tumor volumes at initial and follow-up investigations were 1975 cm(3) (172-9756 cm(3); median, 1490) and 3545 cm(3) (442-15211 cm(3); median, 2846), respectively. Mean growth rate of tumor volume was 2912 cm(3)/year (216-12548 cm(3)/year; median, 1698), and volume doubling times varied from 0.05 to 7.1 years (mean, 1.2; median, 0.7). Significant correlations were observed between initial wall thickness and volume growth rate (p = 0.004). No significant difference was observed between other initial tumor size and growth rate.

CONCLUSION

The tumor growth doubling time of colorectal cancer has a very broad aspect. The initial wall thickness of the tumor on MDCT appears to be the most powerful parameter showing correlation with the volume growth rate.

The accuracy of multi-detector row computerized tomography in staging rectal cancer compared to endoscopic ultrasound

BACKGROUND/AIM

Our aim was to evaluate the diagnostic accuracy of multi-detector row computerized tomography (MDCT) in staging of rectal cancer by comparing it to rectal endoscopic ultrasound (EUS).

MATERIALS AND METHODS

We prospectively included all patients with rectal cancer referred to our gastroenterology unit for staging of rectal cancer from December 2007 until February 2011, 53 patients whose biopsy had proven rectal cancer underwent both MDCT scan of the pelvis and rectal EUS. Both imaging modalities were compared and the agreement between T- and N-staging of the disease was assessed.

RESULTS

We staged 62 patients with rectal cancer during the study period. Of these, 53 patients met the inclusion criteria and were evaluated (25 women and 28 men). The mean age was 57.79 ± 14.99 years (range 21-87). MDCT had poor accuracy compared with EUS in T-staging with a low degree of agreement (kappa = 0.26), while for N-staging MDCT had a better accuracy and a moderate degree of agreement with EUS (kappa = 0.45).

CONCLUSIONS

MDCT has a poor accuracy for predicting tumor invasion compared to EUS for T-staging while it has moderate accuracy for N-staging.

Role of the standardized uptake value of 18-fluorodeoxyglucose positron emission tomography-computed tomography in detecting the primary tumor and lymph node metastasis in colorectal cancers

PURPOSE

To assess the role of positron emission tomography-computed tomography (PET-CT) and multidetector-row CT (MD-CT) in detecting the primary lesion and lymph node metastasis in patients with colorectal cancers.

METHODS

A collective total of 80 lesions resected from 77 patients were examined pathologically. We analyzed the significance of the standardized uptake value (SUV) and its relationship with the clinicopathologic findings of primary lesions and lymph node metastasis. The detectability of primary lesions and lymph node metastases on PET-CT images was compared with that on MD-CT images.

RESULTS

The detectability of primary lesions was better on PET-CT images than on MD-CT images (p = 0.0023). We observed no significant differences in the SUV with respect to staging, tumor grade, lymphatic or vessel invasion, and macroscopic type; however, primary tumor size analysis revealed that tumors larger than 3 cm had a higher SUV than those smaller than 3 cm. The sensitivity of PET-CT for detecting lymph node metastasis was lower than that of MD-CT, but the specificity of PET-CT was higher than that of MD-CT.

CONCLUSIONS

The SUV of primary cancers tends to increase in proportion to tumor size. Although the value of PET-CT in detecting lymph node metastasis is limited, PET -positive lymph nodes can be considered metastatic.

Application of endoscopic sonography in preoperative staging of rectal cancer: six-year experience

OBJECTIVES

The aim of this study was to evaluate our experience with the application of endoscopic sonography in preoperative staging of rectal cancer.

METHODS

Between April 2004 and May 2010, 192 patients with rectal cancer first underwent endoscopic sonography and then underwent surgery at our hospital. None of the patients in this study received neoadjuvant therapy. The endoscopic sonographic staging results were compared with those of postoperative pathologic staging.

RESULTS

The accuracy of overall T staging was 86.5%, and for T1, T2, T3, and T4, the accuracy rates were 86.7%, 94.0%, 86.2%, and 65.5%, respectively. The accuracy of T staging for ulcerated lesions was significantly lower than that for nonulcerated lesions (P = .013). The accuracy of T staging between nontraversable stenotic lesions and traversable lesions was also significantly different (P = .002). The accuracy of N staging was 77.8%, and the specificity and sensitivity were 85.6% and 74.2%, respectively.

CONCLUSIONS

Endoscopic sonography is safe and effective for preoperative staging of rectal cancer and should be a routine examination before surgery. As for ulcerated and nontraversable stenotic lesions, however, the results of endoscopic sonographic staging could be doubtful. Moreover, the accuracy of endoscopic sonographic N staging still needs modification by further research.

MDCT with multiplanar reconstruction in the preoperative local staging of rectal tumor

OBJECTIVE

To evaluate the accuracy of MDCT with multiplanar reconstruction in the preoperative local staging of rectal tumor.

MATERIALS AND METHODS

Thirty-seven patients with rectal tumor underwent preoperative MDCT. Two radiologists evaluated the depth of tumor invasion (T staging), regional lymph node involvement (N staging) and mesorectal fascia involvement on axial, sagittal, and coronal multiplanar reconstruction images in consensus. MDCT findings were compared with pathologic results, which served as the reference standard. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were assessed.

RESULTS

Overall accuracy was 86% in T staging, 84% in N staging, 89% in International Union Against Cancer (UICC) Staging, and 94.5% in the prediction of mesorectal fascia involvement.

CONCLUSION

MDCT with multiplanar reconstruction is an accurate technique in the preoperative local staging of rectal tumor.

Colorectal cancer and 18FDG-PET/CT: What about adding the T to the N parameter in loco-regional staging?

AIM: To evaluate whether FDG-positron emission tomography (PET)/computed tomography (CT) may be an accurate technique in the assessment of the T stage in patients with colorectal cancer.

METHODS: Thirty four consecutive patients (20 men and 14 women; mean age: 63 years) with a histologically proven diagnosis of colorectal adenocarcinoma and scheduled for surgery in our hospital were enrolled in this study. All patients underwent FDG-PET/CT preoperatively. The primary tumor site and extent were evaluated on PET/CT images. Colorectal wall invasion was analysed according to a modified T classification that considers only three stages (≤ T2, T3, T4). Assessment of accuracy was carried out using 95% confidence intervals for T.

RESULTS: Thirty five/37 (94.6%) adenocarcinomas were identified and correctly located on PET/CT images. PET/CT correctly staged the T of 33/35 lesions identified showing an accuracy of 94.3% (95% CI: 87%-100%). All T1, T3 and T4 lesions were correctly staged, while two T2 neoplasms were overstated as T3.

CONCLUSION: Our data suggest that FDG-PET/CT may be an accurate modality for identifying primary tumor and defining its local extent in patients with colorectal cancer.

The value of true axial imaging for CT staging of colonic cancer

OBJECTIVE

To assess the effect of true axial computed tomography on the accuracy of staging of colonic cancers.

METHOD

Fifty consecutive datasets were independently assessed by three radiologists, experienced in colorectal cancer staging. The first read was of standard axial images only. The second read was 6 weeks later and true axial images, through the tumour and perpendicular to its long axis, were included.

RESULTS

The overall accuracy for tumour staging was 56% for reader 1, 48% for reader 2 and 64% for reader 3 for standard axial CT. This improved to 72% (p = 0.012), 66% (p = 0.012) and 80% (p = 0.021) when the true axial images were added. For nodal staging, overall accuracy improved from 56% to 70% (p = 0.065) for reader 1, 58% to 76% (p = 0.012) for reader 2 and 60% to 76% (p = 0.021) for reader 3 between reads.

CONCLUSION

The accuracy of CT staging of colonic tumours is significantly improved by reviewing images reconstructed in a plane perpendicular to the long axis of the tumour. The accuracy achieved by this analysis is similar to that of CT colonography but avoids the extra complexity, additional cost and increased complications.

Prospective assessment of imaging after preoperative chemoradiotherapy for rectal cancer

BACKGROUND

The aim of the study was to assess the accuracy of imaging techniques in predicting pathologic tumor (ypT), node (ypN) stages and the circumferential resection margin (ypCRM) status of rectal cancers after preoperative chemoradiotherapy (CRT).

METHODS

Using pelvic computed tomography (CT), magnetic resonance imaging (MRI), and endorectal ultrasound (ERUS), 90 consecutive patients with locally advanced mid-to-low rectal cancer were prospectively assessed. Postirradiation T and N stages and infiltration of the CRM, as assessed by CT, MRI and ERUS, were compared with histopathologic findings.

RESULTS

The accuracy of ypT staging was low, whatever the imaging technique used (37% by CT, 34% by MRI, and 27% by ERUS), the most frequent inaccuracy being overstaging. Imaging showed a good specificity and good negative predictive values (NPV) when mural staging was grouped into ypT ≤ 3 and ypT4 categories; in particular, ERUS achieved a 92% specificity and 95% NPV. CRM involvement was correctly predicted in 71% of patients by CT (74% specificity; 93% NPV) and in 85% by MRI (88% specificity; 95% NPV). The accuracy for nodal staging was 62%, 68%, and 65% by CT, MRI and ERUS, respectively; the corresponding NPV were 88%, 78%, and 76%.

CONCLUSION

Current imaging techniques are inaccurate in restaging rectal cancer after CRT but are useful in predicting T ≤ 3 tumors, cases with negative nodes and tumor-free CRM. These findings may be of clinical relevance for planning less invasive surgery.

Can CT replace MRI in preoperative assessment of the circumferential resection margin in rectal cancer?

The surgical circumferential resection margin in total mesorectal excision surgery is defined by the relationship of the tumor to the mesorectal fascia. Patients with anticipated tumor invasion of the mesorectal fascia receive neoadjuvant therapy to downstage/downsize the tumor and to obtain tumor-free resection margins.Tumor relationship to the mesorectal fascia is accurately determined by MRI. Compared with MRI, multidetector-row computed tomography is more widely available, faster, less costly, and provides the ability to simultaneously assess the liver, peritoneum, and retroperitoneum for metastases.

PURPOSE

The objective of this study was to compare the accuracy of multidetector-row CT with conventional MRI in diagnosis of rectal cancer invasion of the mesorectal fascial envelope.

MATERIALS AND METHODS

During a 2-year period, all patients were enrolled in this study who had biopsy-proven rectal carcinoma and were referred, as a part of the routine preoperative staging workup, for a CT scan of the abdomen and pelvis and also an MRI of the pelvis.All examinations were reviewed independently by 2 radiologists who were blinded from one another, from the findings of the other modality, and from clinical information. Both observers were dedicated abdominal radiologists who are experienced in reading pelvic CT and MRI. Categorical agreement between MRI and multidetector-row CT for all the evaluated parameters of the tumor position, mesorectal fascia, and lymph nodes, as well as the interobserver agreement between CT and MRI, was determined by the intraclass correlation weighted kappa statistic to measure the data set's consistency.

RESULTS

Among the study's 92 patients, the tumor characteristics suggested by multidetector-row CT agreed with those of MRI, with a weighted kappa ranging from 0.488 to 0.748 for the first reader and 0.577 to 0.800 for the second reader. Interobserver agreement ranged from 0.506 to 0.746.Agreement regarding mesorectal fascia characteristics differed significantly between multidetector-row CT and MRI, depending on the level of assessment. In the distal rectum, agreement was 0.207 for the first reader and 0.385 for the second reader. In the mid rectum, agreement was 0.420 and 0.527, respectively, and in the proximal rectum agreement was 0.508 and 0.520. Interobserver agreement was 0.737 at the distal level and 0.700 at the mid and proximal levels. Agreement regarding measurement of the distance from the tumor to the mesorectal fascia was 0.425 for the first reader and 0.723 for the second reader, with interobserver agreement of 0.766. Agreement in assessment of the number of lymph nodes ranged from 0.743 to 0.787 for the first reader and 0.754 to 0.840 for the second reader. Interobserver agreement ranged from 0.779 to 0.841. Agreement in assessment of the size of the lymph nodes ranged from 0.540 to 0.830 for the first reader and 0.850 to 0.940 for the second reader. Interobserver agreement ranged from 0.900 to 0.920. Agreement in assessment of the distance from nodes to the mesorectal fascia was 0.320 for the first reader and 0.401 for the second reader, with interobserver agreement of 0.950.

CONCLUSION

The results of this study differ from previously published data by demonstrating substantial agreement between readers in multidetector-row CT assessment of the tumor, mesorectal fascia, and lymph nodes. With the exceptions of mesorectal fascia in the distal rectum and the distance from the nodes to mesorectal fascia, other evaluated parameters were assessed with moderate and substantial agreement between multidetector-row CT and MRI. However, our findings suggest that multidetector-row CT does not correlate well enough with MRI findings to replace it in rectal cancer staging.

Preoperative investigations for metastatic staging of colon and rectal cancer across multiple centres--what is current practice?

OBJECTIVE

The optimal strategy for elective distant staging of colorectal carcinoma (CRC) has yet to be defined, with current guidelines based on small and limited series. One specific issue requiring review is the value of routine computerized tomographic (CT) chest examination. Also lacking is data on current routine clinical practice.

METHOD

A retrospective chart review of consecutive cases of elective surgery for CRC from five hospitals.

RESULTS

Two hundred and fifty-seven cases were reviewed, 128 colon and 129 rectal primaries. 164 (64%) of patients overall, ranging from 45% to 88% across the individual centres, had a preoperative serum CEA level performed. CT abdomen/pelvis was performed in 222 (86%) of cases, ranging from 69% to 98% per centre. CT chest was performed in 95 (37%) of cases, 47% of rectal vs 29% of colon cancers (P = 0.004). In 17 cases (18%) CT chest examinations revealed abnormalities suspicious for metastatic disease, leading to a change in management in six (35%) of these cases. Of the 17 cases with an abnormal CT chest, in only 5 of the 14 (36%) where carcinoembryonic antigen (CEA) levels were also recorded was this increased, and in only three (21%) was this markedly (> 10 microg/l) elevated.

CONCLUSIONS

Substantial variability exists in the preoperative evaluation of patients with CRC. Many patients do not have a CEA and/or abdominal imaging performed. Where performed, CT chest revealed suspicious findings in a significant number of patients, the vast majority of whom had a normal or near normal CEA. Future studies are required to define optimal preoperative staging.

Multi-detector CT in peritoneal carcinomatosis: diagnostic role of thin slices and multiplanar reconstructions

BACKGROUND

In order to investigate whether 1-mm thin slices and multiplanar reconstructions (MPRs) of multi-detector computed tomography (CT) datasets interpreted in addition to isotropic 5-mm thick slices in one session improve the detection of peritoneal carcinomatosis.

METHODS

The abdominal CT datasets of 44 patients with histologically proven tumors of the abdomen or pelvis were retrospectively evaluated for peritoneal carcinomatosis by four radiologists with variable experience (radiologist 1: >or=10 years, radiologists 2 and 3: 1.5 years, radiologist 4: 0.5 years). In three successive steps, the radiologists evaluated first the axial 5-mm slices, second the 1-mm slices, and third the MPRs and rated their diagnostic confidence.

RESULTS

Specificity was nearly unchanged for all the four radiologists. Sensitivity improved for the most experienced and the least experienced radiologists and was unchanged for the two readers with intermediate skills. Except for the third step of radiologist 4, no statistically significant differences in diagnostic performance were detected. The diagnostic confidence of all the four readers benefited to variable degrees from interpretation of the 1-mm slices and MPRs.

CONCLUSIONS

While 5-mm slices are sufficient for the detection of peritoneal carcinomatosis, 1-mm slices and MPRs can improve sensitivity and diagnostic confidence.

The accuracy of Multi-detector row CT for the assessment of tumor invasion of the mesorectal fascia in primary rectal cancer

Purpose

To evaluate the accuracy of Multi-detector row CT (MDCT) for the prediction of tumor invasion of the mesorectal fascia (MRF).

Materials and methods

A total of 35 patients with primary rectal cancer underwent preoperative staging magnetic resonance imaging (MRI) and MDCT. The tumor relationship to the MRF, expressed in 3 categories (1—tumor free MRF = tumor distance ≥ 1 mm; 2—threatened = distance < 1 mm; 3—invasion = distance 0 mm) was determined on CT by two observers at patient level and at different anatomical locations. A third expert reader evaluated the MRF tumor relationship on MRI, which served as reference standard. Receiver operating characteristic curves (ROC-curves) and areas under these curves (AUC) were calculated. The inter-observer agreement of CT was determined by using linear weighted kappa statistics.

Results

The AUC of CT for MRF invasion was 0.71 for observer 1 and 0.62 for observer 2. The inter-observer agreement was kappa = 0.34. The performance of CT at mid-high rectal levels was statistically significant better compared to low anterior (obs.1: AUC = 0.88 vs. 0.50; obs 2: AUC = 0.84 vs. 0.31; P ≤ 0.040).

Conclusion

Multi-detector row CT has a poor accuracy for predicting MRF invasion in low-anterior located tumors.The accuracy of CT significantly improves for tumors in the mid-high rectum. There is a high inconsistency among readers.

Preoperative staging of colorectal cancer: CT vs. integrated FDG PET/CT

Accurate preoperative staging is essential in determining the optimal therapeutic planning for individual patients. The computed tomography (CT) in the preoperative staging of colorectal cancer, even if controversial, may be useful for planning surgery and/or neoadjuvant therapy, particularly when local tumor extension into adjacent organs or distant metastases are detected. There have been significant changes in the CT technology with the advent of multi-detector row CT (MDCT) scanner. Advances in CT technology have raised interest in the potential role of CT for detection and staging of colorectal cancer. In recent studies, MDCT with MPR images has shown promising accuracy in the evaluation of local extent and nodal involvement of colorectal cancer. Combined PET/CT images have significant advantages over either alone because it provides both functional and anatomical data. Therefore, it is natural to expect that PET/CT would improve the accuracy of preoperative staging of colorectal cancer. The most significant additional information provided by PET/CT relates to the accurate detection of distant metastases. For the evaluation of patients with colorectal cancer, CT has relative advantages over PET/CT in regard to the depth of tumor invasion through the wall, extramural extension, and regional lymph node metastases. PET/CT should be performed on selected patients with suggestive but inconclusive metastatic lesions with CT. In addition, PET/CT with dedicated CT protocols, such as contrast-enhanced PET/CT and PET/CT colonography, may replace the diagnostic CT for the preoperative staging of colorectal cancer.

[MR-endoscopic US correlation for loco-regional staging of rectal carcinoma]

INTRODUCTION

To correlate findings at high-resolution MR and endoscopic US (EUS) for preoperative loco-regional staging of rectal carcinoma.

PATIENTS AND METHODS

Fifty-two patients with rectal carcinoma underwent high-resolution MR imaging. Only 43 of these patients underwent EUS due to technical limitations and stenosing carcinomas. Morphological imaging features and TNM staging were evaluated for both imaging modalities. The degree of correlation and accuracy were calculated for both.

RESULTS

The correlation between MR and EUS was good for tumor length and thickness (r=0.7 and 0.61) for for nodal (N) staging (k=0.53). Correlation was good for T1 and T2 stages (k=0.51) and T3 stage (k=0.43) and very poor for stage 4 (k= -0.09), because no T4 lesion was detected at EUS. 81.8% of patients where T stage was over-estimated on MRI and 100% of patients where T stage was over-estimated on EUS had received preoperative radiation therapy. Therefore, results should be interpreted with caution. The predictive evaluation of tumor resectability (absence of perirectal fascia invasion) with a circumferential margin on MR> or =5 mm was 93%.

CONCLUSION

Correlation between MR and EUS was moderate for T staging, because of limitations of EUS for large tumors. Results confirm that high-resolution MRI is useful for loco-regional staging of rectal carcinoma, especially for large tumors. EUS should be limited to the valuation of superficial tumors of the rectum.

Comparison between 3-T magnetic resonance imaging and multi-detector row computed tomography for the preoperative evaluation of rectal cancer

OBJECTIVE

To compare prospectively between 3-T magnetic resonance imaging (MRI) and multidetector row computed tomography (MDCT) for the local staging of rectal cancer.

MATERIALS AND METHODS

During a recent 8-month period, both 3-T MRI with a phased array coil and MDCT scanner were used to preoperatively examine 31 consecutive patients. Preoperatively, the 3 experienced reviewers independently assessed the MRI and MDCT findings for the depth of tumor invasion into the rectal wall (T). Regional lymph node metastasis (N) was assessed by the 3 reviewers working in consensus. For T staging, we used a modified T staging (<or=T2, T3, and T4 staging). The results of the MRI and MDCT findings were compared based on the diagnosis of the resected specimens.

RESULTS

At histopathology, T1 was identified in 8 patients, T2 in 6, and T3 in 17 patients. The sensitivity, specificity, and accuracy for T2 staging or less between MRI and MDCT were 93% and 79%, 88% and 76%, and 91% and 77%, respectively. The sensitivity, specificity, and accuracy for T3 between MRI and MDCT were 92% and 73%, 93% and 83%, and 92% and 78%, respectively; there was a statistically significant difference for the T2 and T3 staging or less (P < 0.01). For N staging, MRI and CT can predict accurately in 88% and 77%, respectively (P > 0.05).

CONCLUSIONS

For local staging of rectal cancer, 3-T MRI is more accurate than MDCT for determining the depth of tumor invasion and the extent of lymph node metastasis.

Rectal cancer staging

Endorectal-US is the most suitable imaging technique in the initial staging of rectal cancer and it is mostly accurate in evaluating early stages and in demonstrating the perirectal spread of cancer tissue. CT is not able to demonstrate the layers of the rectal wall and its accuracy in demonstrating the invasion of muscolaris propria and perirectal fat is lower than other techniques, so its use in local staging is not recommended. MRI is mostly accurate in evaluating the mesorectum and the mesorectal fascia which are considered the most relevant prognostic factors for local recurrence. Lymph node evaluation is a challenge for every imaging techniques since lymph node size is not a reliable criterion for diagnosing metastatic involvement. Nuclear medicine has a remarkable role in the work-up of rectal cancer and in the next future the combination of FDG PET in conjunction with a dedicated contrast enhanced CT protocols could become a single-step staging procedure.

A prospective comparison study for predicting circumferential resection margin between preoperative MRI and whole mount sections in mid-rectal cancer: significance of different scan planes

AIM

The aim of this study is to evaluate the accuracy of preoperative magnetic resonance imaging (MRI) in the prediction of circumferential resection margin (CRM) and to determine whether each different MRI scan plane provides an accurate CRM assessment.

METHOD

Fifty-seven consecutive patients with mid-rectal cancer were enrolled prospectively. The CRM measurement from each MRI plane according to tumor location was compared with CRM measurement on whole-mount sections with the definition of threatened CRM as 2 mm in distance. The difference in performance among the sagittal, axial and oblique MR images was analyzed by using receiver operating characteristic (ROC) curves (A(z)).

RESULTS

For anterior tumors (n = 17), the A(z) of the sagittal, axial and oblique MR planes were 0.66, 0.83 and 0.79, respectively. For lateral tumors (n = 17), the A(z) of the sagittal, axial and oblique MR planes were 0.53, 0.66 and 0.78, respectively. For posterior tumors (n = 23), the A(z) of the sagittal, axial and oblique MR planes were 0.76, 0.82 and 0.97, respectively.

CONCLUSIONS

MRI provides an accurate prediction of preoperative CRM. There exist differences in diagnostic accuracy according to each different scan plane of MRI and tumor location within the rectum.

Assessment of hilar and extrahepatic bile duct cancer using multidetector CT: value of adding multiplanar reformations to standard axial images

To retrospectively assess the value of multiplanar reformations (MPRs) compared with standard axial images in the assessment of hilar and extrahepatic bile duct cancer. Forty-eight patients with confirmed bile duct cancer were included as preoperative work-ups; all of these patients underwent contrast-enhanced multidetector CT consisting of axial and MPR images. Two radiologists independently assessed the axial images alone and the combined axial and MPR images in the coronal and sagittal planes for the presence of tumor, its extent, vascular involvement, and resectability. The results were compared with surgical and pathologic findings. For tumor presence and conspicuity, combined axial and MPR images had higher values than the axial only images. For evaluation of tumoral extent, there was no difference between the two image sets for either reader. The accuracy for tumor extent was lower in hilar cancer than in extrahepatic bile duct cancer. For evaluation of vascular involvement and resectability, the area under the receiver operating characteristic curve of axial images was not significantly different from that of the reformatted images. The addition of MPR images to the standard axial images did not significantly improve the diagnostic performance of MDCT in the evaluation of the bile duct cancer.

Contemporary Imaging for Colorectal Cancer

With improvements in therapy for colorectal cancer, accurate imaging has taken on an increased significance. Preoperative diagnosis of metastatic disease helps identify patients who could undergo combined resection or might benefit from systemic therapy before surgery. Accurate imaging of rectal cancer is critical in evaluating locally advanced disease treatable by combined modality therapy, including chemoradiation and surgery. Postoperative imaging enhances identification of recurrent disease that might be amenable to salvage surgery.

Trends in oncological CT imaging: clinical application of multidetector-row CT and 3D-CT imaging

Computed tomography (CT) plays an essential role in oncological imaging as the modality of screening for malignancies, mapping out the treatment strategy at staging, assessing response to the treatment, and following up patient outcome after the treatment. The advent of multidetector-row CT (MDCT) has brought about dramatic changes in clinical oncological imaging. The very superior temporal and spatial resolution of MDCT has transformed CT imaging from a transaxial cross-sectional technique into an isotropic volume-imaging technique. MDCT facilitates multiphasic contrast-enhanced study for a wide range of body scanning in a single examination, as well as providing flexibility of multidirectional reconstruction and high-quality three-dimensional imaging. With increases in the number of detector rows year by year, systems with 64-detector rows have become commercially available in 2006. The purpose of this article is to review the status of CT imaging in oncological imaging: (1) to outline the impact of MDCT, focusing on oncological imaging and (2) to review the clinical applications of oncological CT imaging with MDCT.

Update on Colorectal Cancer Imaging

Colorectal cancer remains a leading cancer killer worldwide. The disease is both curable and preventable, and yet the importance of widespread screening is only now starting to be appreciated. This article reviews the variety of diagnostic tests, imaging procedures and endoscopic examinations available to detect colorectal cancer and polyps in their early stage and also presents details on various screening options. The critical role of the radiologist is elaborated on including accurate assessment of the tumor extent within the bowel wall and beyond and the detection of lymph node and distant metastases. Staging with CT, MR imaging, endorectal ultrasound, and positron emission tomography are of paramount importance in determining the most appropriate therapy and the risk of tumor recurrence and overall prognosis.

Diagnostic value of multidetector row CT in rectal cancer staging: comparison of multiplanar and axial images with histopathology

AIM

Although magnetic resonance (MR) imaging is widely used for rectal cancer staging, many centres in the UK perform computed tomography (CT) for staging rectal cancer at present. Furthermore in a small proportion of cases contraindications to MR imaging may lead to staging using CT. The purpose of this study was to evaluate the accuracy of current generation multidetector row CT (MDCT) in local staging of rectal cancer. In particular the accuracy of multiplanar (MPR) versus axial images in the staging of rectal cancer was assessed.

MATERIAL AND METHODS

Sixty-nine consecutive patients were identified who had undergone staging of rectal cancer on CT. The imaging data were reviewed as axial images and then as MPR images (coronal and sagittal) perpendicular and parallel to the tumour axis. CT staging on axial and MPR images was then compared to histopathological staging.

RESULTS

MPR images detected more T4 and T3 stage tumours than axial images alone. The overall accuracy of T-staging on MPR images was 87.1% versus 73.0% for axial images alone. The overall accuracy of N staging on MPR versus axial images was 84.8% versus 70.7%. There was a statistically significant difference in the staging of T3 tumours between MPR and axial images (p<0.001).

CONCLUSION

Multidetector row CT has high accuracy for local staging of rectal cancer. Addition of MPR images to standard axial images provides higher accuracy rates for T and N staging of rectal cancer than axial images alone.

Preoperative Staging of Rectal Cancer: Comparison of 3-T High-Field MRI and Endorectal Sonography

OBJECTIVE

The aim of this study was to compare phased-array 3-T MRI and endorectal sonography in the preoperative staging of rectal cancer.

MATERIALS AND METHODS

During an 8-month period, 24 patients with rectal cancer underwent both 3-T MRI performed with phased-array coils and 7.5- to 10-MHz endorectal sonography in the 3 weeks before surgical resection. Three radiologists independently reviewed the MR and endorectal sonographic images. The histopathologic findings in resected specimens were used to evaluate the sensitivities and specificities of these techniques for invasion of the muscularis propria and perirectal tissue and for lymph node involvement. Receiver operating characteristic (ROC) analysis was used to compare the diagnostic accuracies of the techniques.

RESULTS

For muscularis propria invasion, the mean sensitivities of both MRI and endorectal sonography were 100%, and the mean specificities were 66.7% and 61.1%, respectively. The differences in the mean sensitivities and specificities were not statistically significant (p > 0.05 in each case). For perirectal tissue invasion, MRI and endorectal sonography had comparable sensitivities and specificities (91.1% vs 100%, 92.6% vs 81.5%; p > 0.05 in each case). They also had similar sensitivities and specificities for lymph node involvement (63.6% vs 57.6%, 92.3% vs 82.1%; p > 0.05 in each case). ROC curves for muscularis propria invasion and lymph node involvement showed no differences in diagnostic accuracy. The mean area under the ROC curve for endorectal sonography (A(Z) = 0.996) for perirectal tissue invasion, however, showed higher accuracy than that of MRI (A(Z) = 0.938, p = 0.028).

CONCLUSION

The sensitivity, specificity, and accuracy of 3-T MRI were similar to those of endorectal sonography for muscularis propria invasion and lymph node involvement, but for perirectal tissue invasion, 3-T MRI was less accurate than endorectal sonography.

Accuracy of single phase contrast enhanced multidetector CT colonography in the preoperative staging of colo-rectal cancer

AIM

The optimal acquisition time for staging colo-rectal carcinoma with a contrast enhanced multidetector CT colonography (CE CTC) has not yet been established. A dual phase with both arterial and portal venous acquisition has been proposed. The purpose of our study is to assess the value of single portal venous phase CE CTC in the preoperative staging of colo-rectal carcinoma.

MATERIALS AND METHODS

Fifty two (30 M, 22 F; aged 35-82 years) consecutive patients with a histologically proven diagnosis of colo-rectal adenocarcinoma or a highly suspected colo-rectal cancer on conventional colonoscopy underwent a four-slice CE CTC. The procedure was performed 70s (portal phase) after the intravenous bolus (3 ml/s) administration of 120 ml iodinated non-ionic contrast agent (370 mg iodine/ml). Scans were performed using the following parameters: 2.5mm beam collimation, pitch 1.25, 120 kV, 200 mAs, rotation time 0.75 s. Images were reconstructed with an effective thickness of 3.2mm at intervals of 1.6mm. Two radiologists independently evaluated the depth of tumour invasion into the colo-rectal wall (T), regional lymph node involvement (N), and extracolonic metastases (M). Disagreement was resolved by means of a consensus decision. The pathological results served as the standard of reference. Assessment was made of sensitivity, specificity and accuracy, as well as positive and negative predictive values were assessed.

RESULTS

CE CTC correctly staged the pT of 52/56 (93%) and the N of 40/56 (71%) lesions, as well as properly identifying 13/14 (93%) extracolonic findings.

CONCLUSION

The single portal venous phase CE CTC scanning protocol enables satisfactory preoperative assessment of T, N and M staging in patients with colo-rectal cancer.

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

PURPOSE

To assess the accuracy of MRI, using a pelvic phased-array coil and an endorectal coil, for preoperative local staging of rectal cancer.

MATERIALS AND METHODS

Fifty-one patients (26 males and 25 females) with adenocarcinoma of the rectum underwent preoperative MRI and surgical resection of their tumors. Surgical pathology staging was compared to MRI staging (using the TNM classification) obtained both retrospectively by a reader blinded to surgical findings and prospectively (radiological reports). In addition, patients were stratified according to surgical treatment groups (stage I = T1-2/N0, stage II = T3/N0, stage III = Tx/N1-2).

RESULTS

At pathology, 36 of 51 (68%) tumors were classified as T0-T2, and 15 (32%) were classified as T3. Overall, the sensitivity and specificity of MRI readings for T3 staging were 93% and 86%, respectively (positive predictive value (PPV) = 74%, negative predictive value (NPV) = 97%, accuracy = 88%). MRI correctly predicted lymph node metastases in 11 of 13 patients with a sensitivity of 85% and specificity of 69% (PPV = 58%, NPV = 90%, accuracy = 74%). MRI correctly predicted surgical treatment groups in 33 of 39 (85%) patients. Interobserver agreement between the retrospective and prospective readings was excellent (kappa = 0.85) for prediction of T3 tumor and good (kappa = 0.80) for prediction of nodal involvement.

CONCLUSION

Combined endorectal and pelvic phased-array coil MRI can be used reliably to select which patients should receive preoperative chemoradiotherapy. It is highly predictive in terms of excluding T3 tumors, but still has limitations in predicting lymph node metastasis.

Positron emission tomography scanning is not superior to whole body multidetector helical computed tomography in the preoperative staging of colorectal cancer

BACKGROUND

The role of positron emission tomography with the glucose analogue [18F] fluoro-2-deoxy-D-glucose (FDG-PET) in the initial staging of disease in patients with primary colorectal cancer (CRC) has not been adequately assessed.

AIMS

To evaluate the additional value of FDG-PET as a staging modality, complementary to routine multidetector row computed tomography (MDCT) in patients with CRC.

METHODS

Forty four patients with CRC underwent preoperative MDCT and FDG-PET. The accuracy of intraoperative macroscopic staging was also investigated compared with histopathological diagnosis. All FDG-PET images were evaluated with respect to detectability of the primary tumour, lymph node involvement, and distant metastases. Both MDCT and FDG-PET diagnoses and treatment plan were compared with surgical and histopathological results.

RESULTS

Thirty seven patients underwent surgery. Tumour detection rate was 95% (42/44) for MDCT, 100% (44/44) for FDG-PET, and 100% (37/37) for intraoperative macroscopic diagnosis. Pathological diagnosis of T factor was T1 in five, T2 in four, T3 in 24, and T4 in four cases. Concordance rate with pathological findings of T factor was 57% (21/37) for MDCT and 62% (23/37) for macroscopic diagnosis. Lymph node involvement was pathologically positive in 19 cases. Regarding N factor, overall accuracy was 62% (23/37) for MDCT, 59% (22/37) for FDG-PET, and 70% (26/37) for macroscopic diagnosis. For all 44 patients, FDG-PET findings resulted in treatment changes in only one (2%) patient.

CONCLUSION

FDG-PET is not superior to routine MDCT in the initial staging of primary CRC.