Diagnostic value of FDG-PET/CT for lymph node metastasis of colorectal cancer

Radiomics from dual-energy CT-derived iodine maps for predicting lymph node metastases in patients with resectable rectal cancer

BackgroundLymph node metastasis (LNM) is a poor prognostic predictor and is highly correlated with local recurrence in rectal cancer patients.ObjectiveTo investigate the value of radiomics from dual-energy CT-derived iodine maps for the preoperative prediction of LNM in rectal cancer patients.MethodsA total of 176 patients were enrolled in this study (training group, n = 123; validation group, n = 53). A radiomic signature was constructed via support vector machine (SVM) modeling. Seven models, including a clinical feature model (Model 1), an arterial model (Model 2), a venous model (Model 3), an arterial-venous model (Model 4), an arterial-clinical model (Model 5), a venous-clinical model (Model 6) and an arterial-venous-clinical model (Model 7), were established via logistic regression modeling. Diagnostic performance was assessed via receiver operating characteristic (ROC) curves.ResultsTumor location and carcinoembryonic antigen levels were used to construct Model 1 (training group, AUC [area under the ROC curve] = 0.721, 95% CI [confidence intervals], 0.630-0.813; validation group, AUC = 0.729, 95% CI, 0.593-0.865). Model 6 and Model 7 further improved the discriminatory performance in the training (AUC = 0.850 and 0.869, 95% CI, 0.782-0.919 and 0.807-0.932, respectively; p = 0.250) and validation groups (AUC = 0.780 and 0.716, 95% CI, 0.653-0.906 and 0.576-0.856, respectively; p = 0.115). Moreover, decision curve analysis revealed a greater net benefit with Model 6.ConclusionsThe combination of radiomic features based on dual-energy CT-derived iodine maps and clinical features provides better diagnostic performance for predicting LNM in rectal cancer patients.

ALK-positive Histiocytosis Mimicking Colon Cancer on 18F-FDG PET/CT

As a subtype of histiocytic neoplasm, ALK-positive histiocytosis is rare, especially with colorectal involvement. We herein describe 18F-FDG PET/CT findings of ALK-positive histiocytosis with colon involvement in a 33-year-old man. The PET/CT scan demonstrated intense FDG uptake in the colonic lesion, along with multiple hypermetabolic lymph nodes. The colon cancer with lymph node metastases was initially suspected; however, the final pathological findings confirmed the diagnosis of ALK-positive histiocytosis.

DNA methylation biomarkers for predicting lymph node metastasis in colorectal cancer

Colorectal cancer is one of the most common cancers worldwide. Lymph node metastasis is an important marker of colorectal cancer progression and plays a key role in the evaluation of patient prognosis. Accurate preoperative assessment of lymph node metastasis is crucial for devising appropriate treatment plans. However, current clinical imaging methods have limitations in many aspects. Therefore, the discovery of a method for accurately predicting lymph node metastasis is crucial clinical decision-making. DNA methylation is a common epigenetic modification that can regulate gene expression, which also has an important impact on the development of colorectal cancer. It is considered to be a promising biomarker with good specificity and stability and has promising application in predicting lymph node metastasis in patients with colorectal cancer. This article reviews the characteristics and limitations of currently available methods for predicting lymph node metastasis in patients with colorectal cancer and discusses the role of DNA methylation as a biomarker.

Evaluation of colon cancer prognostic factors by CT and MRI: an up-to-date review

Colorectal cancer (CRC) is a significant global health concern. Prognostication of CRC traditionally relies on the Union for International Cancer Control (UICC) and American Joint Committee on Cancer (AJCC) TNM staging classifications, yet clinical outcomes often vary independently of stage. Despite similarities, rectal and colon cancers are distinct in their diagnostic methodologies and treatments, with MRI and CT scans primarily used for staging rectal and colon cancers, respectively. This paper examines the challenges in accurately assessing prognostic factors of colon cancer such as primary tumor extramural extension, retroperitoneal surgical margin (RSM) involvement, extramural vessel invasion (EMVI), and lymph node metastases through preoperative CT and MRI. It highlights the importance of these factors in risk stratification, treatment decisions, and surgical planning for colon cancer patients. Advancements in imaging techniques are crucial for improving clinical management and optimizing patient outcomes, underscoring the necessity for ongoing research to refine diagnostic methods and incorporate novel findings into practice.

The role of MRI in radiotherapy planning: a narrative review "from head to toe"

Over the last few years, radiation therapy (RT) techniques have evolved very rapidly, with the aim of conforming high-dose volume tightly to a target. Although to date CT is still considered the imaging modality for target delineation, it has some known limited capabilities in properly identifying pathologic processes occurring, for instance, in soft tissues. This limitation, along with other advantages such as dose reduction, can be overcome using magnetic resonance imaging (MRI), which is increasingly being recognized as a useful tool in RT clinical practice. This review has a two-fold aim of providing a basic introduction to the physics of MRI in a narrative way and illustrating the current knowledge on its application "from head to toe" (i.e., different body sites), in order to highlight the numerous advantages in using MRI to ensure the best therapeutic response. We provided a basic introduction for residents and non-radiologist on the physics of MR and reported evidence of the advantages and future improvements of MRI in planning a tailored radiotherapy treatment "from head to toe". CRITICAL RELEVANCE STATEMENT: This review aims to help understand how MRI has become indispensable, not only to better characterize and evaluate lesions, but also to predict the evolution of the disease and, consequently, to ensure the best therapeutic response. KEY POINTS: MRI is increasingly gaining interest and applications in RT planning. MRI provides high soft tissue contrast resolution and accurate delineation of the target volume. MRI will increasingly become indispensable for characterizing and evaluating lesions, and to predict the evolution of disease.

Assessment of the Diagnostic Accuracy of CT as Compared to MRI in Detecting Metastases in Patients With Colorectal Cancer

This study aimed to compare the diagnostic accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) in detecting metastases of colorectal cancer (CRC) in a hospital in Najran, Saudi Arabia. A total of 51 patients with CRC were included in the study. The radiological findings of metastatic lesions and the diagnostic accuracy measures of CT compared to MRI were analyzed. The results showed that CT had a false negative rate of 7.8%, a false positive rate of 7.8%, a true negative rate of 27.5%, and a true positive rate of 56.9% in detecting metastases. Diagnostic accuracy measures varied based on the number of metastatic lesions, with higher sensitivity observed for cases with fewer lesions. Gender, timing of imaging in relation to surgical intervention, and administration of nonsurgical therapy showed significant associations with diagnosis mismatch between CT and MRI. The site of metastases and the site of the primary tumor in the colon also demonstrated significant associations with diagnosis mismatch. The size of the largest metastasis detected by MRI was significantly associated with diagnosis mismatch. The overall diagnostic accuracy of CT in detecting any metastases, compared to MRI as the reference standard, was estimated to have a sensitivity of 87.8%, a specificity of 77.8%, a positive predictive value of 87.8%, and a negative predictive value of 77.8%. This study provides valuable insights into the comparative diagnostic performance of CT and MRI in detecting metastases of CRC, highlighting the importance of considering patient characteristics, disease outcome, and tumor characteristics in the interpretation of imaging results.

Imaging and Metabolic Diagnostic Methods in the Stage Assessment of Rectal Cancer

Rectal cancer (RC) is a prevalent malignancy with significant morbidity and mortality rates. The accurate staging of RC is crucial for optimal treatment planning and patient outcomes. This review aims to summarize the current literature on imaging and metabolic diagnostic methods used in the stage assessment of RC. Various imaging modalities play a pivotal role in the initial evaluation and staging of RC. These include magnetic resonance imaging (MRI), computed tomography (CT), and endorectal ultrasound (ERUS). MRI has emerged as the gold standard for local staging due to its superior soft tissue resolution and ability to assess tumor invasion depth, lymph node involvement, and the presence of extramural vascular invasion. CT imaging provides valuable information about distant metastases and helps determine the feasibility of surgical resection. ERUS aids in assessing tumor depth, perirectal lymph nodes, and sphincter involvement. Understanding the strengths and limitations of each diagnostic modality is essential for accurate staging and treatment decisions in RC. Furthermore, the integration of multiple imaging and metabolic methods, such as PET/CT or PET/MRI, can enhance diagnostic accuracy and provide valuable prognostic information. Thus, a literature review was conducted to investigate and assess the effectiveness and accuracy of diagnostic methods, both imaging and metabolic, in the stage assessment of RC.

Diagnostic role of F-18 FDG PET/CT in determining preoperative Lymph node status of patients with rectal cancer: a meta-analysis

PURPOSE

To obtain performance values of PET/CT for determining the nodal status of rectal cancer.

MATERIALS

A comprehensive literature search was performed on PubMed and Embase for original diagnostic accuracy studies on the diagnostic performance of PET-CT for detection of LN metastasis in rectal cancer. The QUADAS-2 was used to evaluate the methodological quality of each study. Pooled sensitivity, specificity, and AUC were calculated to estimate the diagnostic role of PET/CT using a random-effects model. A subgroup analysis was performed to investigate the influence of different parameters on diagnostic performance.

RESULTS

A total of 15 studies and 1209 patients were included. A publication bias was observed. The pooled sensitivity, specificity, and AUC for PET/CT was 0.62 (95% CI 0.49, 0.74), 0.94 (95% CI 0.87, 0.97), and 0.87 (95% CI 0.83-0.89), respectively. Per-node basis yields higher accuracy than per-patient basis, with pooled sensitivities of 0.65 (95% CI 0.50-0.79) vs. 0.56 (95% CI 0.36-0.77) and specificities of 0.96 (95% CI 0.92-1.00) vs. 0.88 (95% CI 0.76-1.00), but there were no significant differences in diagnostic accuracy.

CONCLUSION

PET/CT has high specificity but moderate sensitivity for the detection of LN metastasis in rectal cancer. The current data suggests that the diagnostic capabilities of this method is limited due to its moderate sensitivity.

Metastatic Colorectal Cancer Treated with Combined Liver Resection, Cytoreductive Surgery, and Hyperthermic Intraperitoneal Chemotherapy (HIPEC): Predictive Factors for Early Recurrence

BACKGROUND

Selection of colorectal cancer patients with concomitant peritoneal (PM) and liver metastases (LM) for radical treatment with cytoreductive surgery (CRS), including liver resection and hyperthermic intraperitoneal chemotherapy (HIPEC), needs improvement. This retrospective, monocentric study was designed to evaluate the predictive factors for early recurrence, disease-free survival (DFS), and overall survival (OS) in such patients treated in a referral center.

METHODS

Consecutive colorectal cancer patients with concomitant LM and PM treated with curative intent with perioperative systemic chemotherapy, simultaneous complete CRS, liver resection, and HIPEC in 2011-2022 were included. Clinical, radiological (before and after preoperative chemotherapy), surgical, and pathological data were investigated, along with long-term oncologic outcomes. A multivariate analysis was performed to identify predictive factors associated with early recurrence (diagnosed <6 months after surgery), DFS, and OS.

RESULTS

Of more than 61 patients included, 31 (47.1%) had pT4 and 27 (40.9%) had pN2 primary tumors. Before preoperative chemotherapy, the median number of LM was 2 (1-4). The median surgical PCI (peritoneal carcinomatosis index) was 3 (5-8.5). The median DFS and OS were 8.15 (95% confidence interval [CI] 5.5-10.1) and 34.1 months (95% CI 28.1-53.5), respectively. In multivariate analysis, pT4 (odds ratio [OR] = 4.14 [1.2-16.78], p = 0.032]) and pN2 (OR = 3.7 [1.08-13.86], p = 0.042) status were independently associated with an early recurrence, whereas retroperitoneal lymph node metastasis (hazard ratio [HR] = 39 [8.67-175.44], p < 0.001) was independently associated with poor OS.

CONCLUSIONS

In colorectal cancer patients with concomitant PM and LM, an advanced primary tumor (pT4 and/or pN2) was associated with a higher risk of early recurrence following a radical multimodal treatment, whereas RLN metastases was strongly detrimental for OS.

Tailoring the clinical management of colorectal cancer by 18F-FDG PET/CT

Colorectal cancer (CRC) is among the most commonly diagnosed gastrointestinal malignancies worldwide. It is inadequate to handle in terms of staging and restaging only based on morphological imaging modalities and serum surrogate markers. And the correct and timely staging of CRC is imperative to prognosis and management. When compared to established sequential, multimodal conventional diagnostic methods, the molecular and functional imaging ¹⁸F-FDG PET/CT shows superiorities for tailoring appropriate treatment maneuvers to each patient. This review aims to summarize the utilities of ¹⁸F-FDG PET/CT in CRC, focusing on primary staging, follow-up assessment of tumor responses and diagnostic of recurrence. In addition, we also summarize the technical considerations of PET/CT and the conventional imaging modalities in those patients who are either newly diagnosed with CRC or has already been treated from this cancer.

A novel DNA methylation marker to identify lymph node metastasis of colorectal cancer

Lymph node metastasis (LNM) of colorectal cancer (CRC) is an important factor for both prognosis and treatment. Given the deficiencies of conventional tests, we aim to discover novel DNA methylation markers to efficiently identify LNM status of CRC. In this study, genome-wide methylation sequencing was performed in a cohort (n=30) using fresh CRC tissue to discover differentially methylated markers. These markers were subsequently validated with fluorescence quantitative PCR in a cohort (n=221), and the optimal marker was compared to conventional diagnostic methods. Meanwhile, immunohistochemistry was used to verify the effectiveness of the antibody corresponding to this marker in a cohort (n=56). LBX2 achieved an AUC of 0.87, specificity of 87.3%, sensitivity of 75.7%, and accuracy of 81.9%, which outperformed conventional methods including imaging (CT, PET-CT) with an AUC of 0.52, CA199 with an AUC of 0.58, CEA with an AUC of 0.56. LBX2 was also superior to clinicopathological indicators including the depth of tumor invasion and lymphatic invasion with an AUC of 0.61and 0.63 respectively. Moreover, the AUC of LBX2 antibody was 0.84, which was also better than these conventional methods. In conclusion, A novel methylation marker LBX2 could be used as a simple, cost-effective, and reliable diagnostic method for LNM of CRC.

Transabdominal Ultrasonography for Preoperative Diagnosis of Lymph Node Metastasis in Colon Cancer: A Retrospective Cohort Study

Background/Aim

Although computed tomography (CT) is the standard modality for diagnosing lymph node metastasis (LNM), transabdominal ultrasonography (US) can be useful due to its high spatial resolution and use of Doppler signals to precisely analyse lymph nodes. This study aimed to evaluate the accuracy of US for lymph node assessment, establish US-based diagnostic criteria for LNM, and compare the capability of US with that of CT for the diagnosis of LNM.

Patients and Methods

This retrospective, single-institution, cohort study included patients who underwent radical surgery for clinical stage 0-III colon cancer, between March 2012 and February 2019.

Results

Overall, 34.9% (66/189) of patients had pathological LNM. The optimal US diagnostic criteria were 1) short axis ≥7 mm and short/long ratio ≥0.75 and 2) at least two of the following: the absence of hilar echoes, expansive appearance, or peripheral/mixed vascularity by the colour Doppler and/or contrast-enhanced method. Compared to CT, US showed a higher diagnostic sensitivity (54.5% vs. 43.9%; p=0.296), higher concordance with the number of pathological LNM (correlation coefficient: US, 0.42; CT, 0.27) and pathological N diagnosis (weighted ĸ: US, 0.35; CT, 0.18), and higher sensitivity for advanced LNM, including multiple LNMs (47.4% vs. 18.4%; p=0.014) and N2 stage (27.8% vs. 5.6%; p=0.177).

Conclusion

US has higher sensitivity than CT for diagnosing LNM in colon cancer, along with a more accurate preoperative diagnosis of the N stage. Additionally, US may be more helpful than CT alone for preoperatively deciding the appropriateness of neoadjuvant treatment in colon cancer with advanced LNM.

Infrapyloric and gastroepiploic node dissection for hepatic flexure and transverse colon cancer: A systematic review

INTRODUCTION

The hepatic flexure and transverse colon have a complex intermingled lymphovascular anatomy crossing between mesocolon and mesogastrium. Few studies have investigated the oncological relevance of metastatic infrapyloric and gastroepiploic lymph nodes (IGLN) from hepatic flexure and transverse colon tumors. This study aimed to evaluate the incidence and risk factors for IGLN metastases, and the indications, surgical morbidities, and oncological outcome following extended lymphadenectomy.

MATERIALS AND METHODS

According to the PRISMA statement, a systematic review on IGLN lymphadenectomy for colon cancer was conducted into PubMed, Embase, and Cochrane databases. A critical appraisal of study was performed according to the Joanna Briggs Institute Tools.

RESULTS

Nine studies were included. IGLN metastases incidence ranged 0.7-22%. IGLN positivity for patients with metastatic mesocolic lymph nodes ranged 1.7-33.3%. Postoperative complication rate ranged 8.5-36.9%, mostly low grade according to Clavien-Dindo's classification. Postoperative mortality rate ranged 0-5.4% at 30-days. IGLN metastases were associated with advanced disease with a 5-year progression-free survival rate up to 33.9%. Two authors reported perineural invasion and N stage as risk factors, while another reported endoscopic obstruction, signet ring adenocarcinoma, CEA level ≥17 ng/ml, and M1 stage to be risk factors for IGLN involvement. Apart from one study, all other studies were of moderate/high quality.

CONCLUSIONS

Metastatic IGLNs are not uncommon and should be highly considered. IGLN metastases could be potentially associated with an aggressive disease. IGLN dissection is not associated with higher morbidity and mortality than standard CME. Preoperative risk factors of IGLN involvement could guide surgical indication for extended lymphadenectomy.

Isolated synchronous Virchow lymph node metastasis of sigmoid cancer: A case report

BACKGROUND

Colorectal cancer (CRC) is one of the most common malignant tumors of the digestive tract. Lymphatic metastases of this tumor are mostly confined to the regional lymph nodes, and distant supraclavicular lymph node metastases are very rare.

CASE SUMMARY

In this report, we describe a patient with sigmoid carcinoma and isolated synchronous supraclavicular lymph node metastases. A 56-year-old male presented with a left cervical mass that was confirmed as a lymph node metastasis from sigmoid cancer by several auxiliary examinations. After 6 cycles of chemotherapy with the 5-fluorouracil, leucovorin and oxaliplatin + cetuximab regimen, the sigmoid colon tumor and Virchow’s lymph node metastasis were significantly smaller than before treatment, and no new metastatic sites were observed. Considering the effects of chemotherapy on quality of life, resection of the primary tumor was performed followed by 4 cycles of chemotherapy with the original chemotherapy regimen. Virchow’s lymph node dissection was selected by mutual consultation between the patient and us. After the second surgery, the patient received capecitabine and cetuximab chemotherapy and did not experience recurrence or metastasis during follow-up.

CONCLUSION

In conclusion, supraclavicular lymph node metastasis without any other solid organ metastasis is a potential metastatic pathway for CRC. In addition, after resection of the primary lesion, postoperative chemotherapy combined with supraclavicular lymph node dissection is feasible for the treatment of patients with CRC and isolated synchronous Virchow’s lymph node metastases.

Investigating ultra-low-dose total-body [18F]-FDG PET/CT in colorectal cancer: initial experience

PURPOSE

This study was to evaluate the effects of an ultra-low dose of [18F]-FDG on the image quality of total-body PET/CT and its lesion detectability in colorectal cancer (CRC).

METHODS

Sixty-two CRC patients who underwent total-body PET/CT (uEXPLORER, United Imaging Healthcare, Shanghai, China) with an ultra-low dose (0.37 MBq/kg) of [18F]-FDG were enrolled in this retrospective study. The PET images were reconstructed with the entire 15-min dataset first and then split into 13-, 8-, 5-, 4-, 3-, 2-, and 1-min duration groups to simulate fast scanning images. For simplicity, the images reconstructed with the data from 15 to 1 min were referred to as G15, G13, and so on until G1. Subjective image quality was assessed with 5-point Likert scales. The objective image quality parameters included the SUVmax, SUVmean, and signal-to-noise ratio (SNR) of the liver and blood pool and the SUVmax and tumor-to-background ratio (TBR) of the lesions. G15 served as the control to evaluate lesion detectability.

RESULTS

A total of 62 patients (43 men, 19 women; age 41-88, mean ± SD 64.0 ± 10.9 years) with 64 CRC primary tumor lesions and 10 low-grade intraepithelial neoplasia (LGIN) lesions were enrolled in this study. The subjective scores were highest for G15 (4.5 ± 0.5) and then decreased from G13 (4.3 ± 0.4) to G8 (3.7 ± 0.5). The liver SNR increased with the extension of acquisition time from G8 (17.2 ± 2.8) to G13 (20.6 ± 3.4) and G15 (21.9 ± 3.4). The liver SNR of G8 was not significantly different from that of G13 (p = 0.15) and was significantly different from that of G15 (p = 0.001). All 64 CRC lesions could be identified in all image groups, even on G1. One of ten LGINs was missed on G1, G2, and G3, and one LGIN was missed on G1, G2, G3, and G4. G15 served as the control, and 100% (48/48) lymph nodes could be found on G13 and G8 compared to 93.8% (45/48) lymph nodes on G5 and G4, 85.4% (41/48) lymph nodes on G3, 81.3% (39/48) lymph nodes on G2, and 77.1% (37/48) lymph nodes on G1. For liver metastases, there were no missed liver lesions on G13 and G8 and 3, 4, 6, 7, and 9 missed liver lesions on G5, G4, G3, G2, and G1, respectively. For other areas of metastasis, including the lung, peritoneum, and ovaries, there were no missed lesions in any group.

CONCLUSIONS

Total-body PET/CT with an ultra-low dose of [18F]-FDG can maintain satisfactory image quality and lesion detectability in CRC.

18F-FDG-PET/CT Imaging for Gastrointestinal Malignancies

Gastrointestinal malignancies encompass a variety of primary tumor sites, each with different staging criteria and treatment approaches. In this review we discuss technical aspects of 18F-FDG-PET/CT scanning to optimize information from both the PET and computed tomography components. Specific applications for 18F-FDG-PET/CT are summarized for initial staging and follow-up of the major disease sites, including esophagus, stomach, hepatobiliary system, pancreas, colon, rectum, and anus.

Value of PET imaging for radiation therapy

This comprehensive review written by experts in their field gives an overview on the current status of incorporating positron emission tomography (PET) into radiation treatment planning. Moreover, it highlights ongoing studies for treatment individualisation and per-treatment tumour response monitoring for various primary tumours. Novel tracers and image analysis methods are discussed. The authors believe this contribution to be of crucial value for experts in the field as well as for policy makers deciding on the reimbursement of this powerful imaging modality.

Value of PET imaging for radiation therapy

This comprehensive review written by experts in their field gives an overview on the current status of incorporating positron emission tomography (PET) into radiation treatment planning. Moreover, it highlights ongoing studies for treatment individualisation and per-treatment tumour response monitoring for various primary tumours. Novel tracers and image analysis methods are discussed. The authors believe this contribution to be of crucial value for experts in the field as well as for policy makers deciding on the reimbursement of this powerful imaging modality.

Can PET/CT detect recurrence in post-operative colorectal carcinoma patients with elevated CEA level?

Background

PET is considered to be the most sensitive and specific modality for the detection of recurrent colorectal cancer. This study is to assess the role of F18-FDG PET/CT in post-operative assessment in a patient with colorectal cancer with elevated CEA level to rule out local recurrence and/or metastasis and hence guiding the clinician to the proper management strategy.

Results

This study was performed on 45 patients who underwent surgical resection of the colon and/or rectal cancer; they were referred for PET/CT assessment at least 3 months after surgical resection. F18-FDG PET/CT sensitivity and specificity in detecting the recurrence and/or metastasis were 96.9 % and 83.3%, respectively. The positive predictive value was 94.2% while the negative predictive value was 90%.

Conclusion

For post-operative detection of loco-regional recurrence and metastasis in patients with colorectal cancer and elevated CEA level, 18F-FDG PET/CT can be considered as an efficient diagnostic imaging tool due to its high sensitivity and specificity which extensively affect further management.

Preoperative heat shock protein 47 levels identify colorectal cancer patients with lymph node metastasis and poor prognosis

Accumulating evidence suggests that overexpression of heat shock protein 47 (HSP47) increases cancer progression, and that HSP47 level in the tumor-associated stroma may serve as a diagnostic marker in various cancers. The present study aimed to evaluate whether HSP47 gene expression in colorectal cancer (CRC) tissues could be used to identify lymph node (LN) metastasis status preoperatively in patients with CRC. To do so, HSP47 gene expression was determined and its association with the clinicopathological characteristics of patients with CRC was analyzed. A total of 139 surgical specimens from patients with CRC and 36 patients with benign colonic disease undergoing surgery at Mie University Hospital were analyzed. HSP47 gene expression was determined by reverse transcription quantitative PCR using Power SYBR Green PCR methods. Expression level of HSP47 was significantly higher in CRC tissues compared with normal tissue from patients with benign colonic disease. Furthermore, high HSP47 expression was significantly associated with tumor progression, including high T stage, lymph node metastasis and venous invasion, and high TNM stage. High HSP47 expression may therefore serve as a novel predictive biomarker for determining patients with CRC and LN metastasis. According to Kaplan-Meier analysis, patients with high HSP47 expression level had significantly poorer overall survival than those with low HSP47 expression level. Furthermore, multivariate analyses identified HSP47 expression as an independent predictive marker for LN metastasis and poor overall survival in patients with CRC. In summary, the present study demonstrated that HSP47 expression may be considered as a novel biomarker for predicting LN metastasis status and prognosis in patients with CRC.

Is 18F-FDG PET/CT an Accurate Way to Detect Lymph Node Metastasis in Colorectal Cancer: A Systematic Review and Meta-Analysis

Aims

The purpose of this study was to assess the diagnostic value of ¹⁸F-fluorodeoxy-glucose positron emission tomography/computed tomography (FDG PET/CT) for detection of lymph node (LN) metastasis of colorectal cancer. Material and Methods. A computerized search was performed to determine the relevant articles, published before October 2019. Stata Statistical Software, version 15.0, and Meta-Disc (version 1.4) were used for the meta-analysis.

Results

the sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were 0.65, 0.75, 4.57, and 0.37 respectively. Studies that used SUV_max cut-off value (≤2.5) demonstrated the best accuracy.

Conclusion

¹⁸F-FDG PET/CT shows a low sensitivity and high specificity for detecting the metastasis of LNs in patients with newly diagnosed colorectal cancer.

Positron emission tomography with computed tomography imaging (PET/CT) for the radiotherapy planning definition of the biological target volume: PART 2

AIM

Positron Emission Tomography with Computed Tomography (PET/CT) has been proven to be useful in the definition of Radiotherapy (RT) target volume. In this regard, the present expert review summarizes existing data for pancreas, prostate, gynecological and rectum/anal cancer.

METHODS

A comprehensive search of published original article was made, based on SCOPUS and PubMed database, selecting the paper that evaluated the role of PET/CT in the definition of RT volume.

RESULTS

FDG-PET has an important and promising role for pancreatic cancer. Choline PET/CT could be useful for identifying high-risk volumes for prostate cancer; while PSMA PET/CT is still under evaluation. FDG PET/CT in gynecological cancers has been shown to impact external-beam RT planning. The role of FDG-PET for Gross Tumor volume identification is crucial, representing a useful and powerful tool for anal and rectal cancer.

CONCLUSION

Taken together, molecular and functional imaging approaches offer a major step to individualize radiotherapeutic approach.

Differentiation between malignant and benign rectal tumors by dual-energy computed tomography - a feasibility study

INTRODUCTION

To assess the performance of Dual Energy Computed Tomography (DECT) in the differentiation between benign and malignant tumors in the rectum.

MATERIAL AND METHODS

We enrolled 8 subjects with rectal tumors suspected to be an early rectal cancer during colonoscopy. All subjects underwent Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Endorectal Ultrasound (ERUS) for staging. Furthermore, all subjects underwent fast switching of tube voltage between 80 and 140 kVp DECT of the pelvis. The 8 subjects had histopathological verified benign adenomas after transanal endoscopic microsurgery resection (TEM). The 8 subjects were matched with 8 consecutively selected subjects with histopathologically verified malignant rectal tumors. The DECT images were analyzed to assess the difference between malignant and benign rectal tumors. All DECT images were reviewed by experienced radiologists. In each DECT scanning, we applied three regions of interest (ROIs) for the acquisition of the DECT unique quantitative parameters. The mean atomic mass (effective Z value), iodine concentration, dual energy ratio (DER) and dual-energy index (DEI) was determined in both groups.

RESULTS

The comparison of the 2 groups showed a significant difference in effective Z and a nonsignificant difference regarding iodine concentration, DER, and DEI in the two groups.

CONCLUSION

Dual-energy CT demonstrated a difference in the mean atomic mass in benign colorectal tumors in comparison to malignant colorectal tumors.

Preoperative Computerized Tomographic Assessment of Regional Lymph Node and Extramural Vascular Invasion in Colonic Cancer

Objective

There have been recent attempts to transfer well-established principles of rectal cancer management to colonic cancer, thereby offering neoadjuvant chemotherapy to high-risk patients at least in the trial settings. Traditionally, postoperative chemotherapy is offered to patients with colonic tumors that metastasize into regional lymph nodes and have features of extramural vascular invasion (EMVI). If the same criteria are used for the selection of patients with colonic cancer for neoadjuvant chemotherapy, then their accurate preoperative detection becomes of paramount importance. The aim of the study was to establish the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the computerized tomographic (CT) assessment of lymph node involvement and EMVI in colonic cancer.

Materials and Methods

This retrospective study included 53 consecutive adult patients (35 males and 18 females; median age, 72 years) who had complete preoperative CT staging of colonic cancer followed by its surgical resection during a 12-month period from January 1, 2012, to December 31, 2012. Patients with rectal and colonic tumors presenting as an emergency who did not have complete preoperative CT imaging were excluded. Preoperative CT findings on regional lymph node status and EMVI were compared with the final histopathological staging of resected specimens calculating sensitivity, specificity, PPV, and NPV of the test.

Results

In predicting regional lymph node metastases, CT scan had a sensitivity of 85% and a specificity of 24%. PPV was calculated as 63% and NPV as 50%. In predicting EMVI, it had a sensitivity of 69% and a specificity of 49%. PPV was 37% and NPV was 78%.

Conclusion

Preoperative CT scan does not allow an accurate detection of regional lymph node metastases and EMVI and has a tendency to overstage colonic cancer.

Clinical lymph node staging in colorectal cancer; a flip of the coin?

BACKGROUND

This study aims to provide insight in the quality of current daily practice in clinical lymph node staging in colorectal cancer (CRC) in the Netherlands.

METHODS

Data of the nationwide population-based Netherlands Cancer Registry between 2003 and 2014 were used to analyze lymph node staging for cM0 CRC patients. Accuracy of clinical lymph node staging was calculated for the period 2011-2014. Analyses were performed for patients without preoperative treatment or treated with short-course radiotherapy (SCRT) followed by resection.

RESULTS

100,211 patients were included for analysis. The proportion clinically positive lymph nodes increased significantly between 2003 and 2014 (6%-22% for colon cancer; 7%-53% for rectal cancer). The proportion histological positive lymph nodes remained stable (±35% colon, ±33% rectum). Data from 2011 to 2014 yielded a sensitivity, specificity, positive and negative predictive value of 41%, 84%, 59% and 71% for colon cancer, respectively (n = 21,629). This was 38%, 87%, 56%, 76% for rectal cancer without SCRT, (n = 2178) and 56%, 67%, 47% and 75% for rectal cancer with SCRT (n = 3401), respectively.

CONCLUSION

Accuracy of clinical lymph node staging in colorectal cancer patients is about as accurate as flipping a coin. This may lead to overtreatment of rectal cancer patients. Acceptable specificity and NPV limit the risk of undertreatment.

Evaluation of recurrence in gastric carcinoma: Comparison of contrast-enhanced computed tomography and positron emission tomography/computed tomography

AIM

To compare the value of contrast-enhanced abdominal computed tomography (CT) and fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for detecting gastric carcinoma recurrence.

METHODS

We retrospectively examined data from 2475 patients who underwent both contrast-enhanced abdominal CT and FDG PET/CT for the surveillance of gastric carcinoma curative resection. Patients had an interval of less than 1 mo between their CT and PET/CT scans. Sixty patients who had recurrence were enrolled. Among 1896 patients who did not have recurrence, 60 were selected by simple random sampling. All CT and PET/CT images were reviewed retrospectively by two reviewers blinded to all clinical and pathologic information except curative resection due to gastric carcinoma.

RESULTS

The pathological stage of the recurrence group was statistically significantly higher than that of the control group (P < 0.001). In the 60 patients who had recurrence, there were 79 recurrent lesions. Forty-four patients had only one location of recurrence, 13 patients had two locations, and 3 patients had three. In the detection of patient-based overall recurrence, no statistically significant differences existed between the two modalities (P = 0.096). However, for peritoneal carcinomatosis, CT had a statistically significantly higher sensitivity compared to PET/CT (96% vs 50%, P = 0.001). Adenocarcinoma was the most common type of gastric carcinoma. On the pathology-based analysis, CT also had a statistically significantly higher sensitivity compared to PET/CT (98% vs 80%, P = 0.035).

CONCLUSION

Contrast-enhanced CT was superior to PET/CT in the detection of peritoneal carcinomatosis and pathologic type of adenocarcinoma.

Dual-energy CT can detect malignant lymph nodes in rectal cancer

BACKGROUND

There is a need for an accurate and operator independent method to assess the lymph node status to provide the most optimal personalized treatment for rectal cancer patients. This study evaluates whether Dual Energy Computed Tomography (DECT) could contribute to the preoperative lymph node assessment, and compared it to Magnetic Resonance Imaging (MRI). The objective of this prospective observational feasibility study was to determine the clinical value of the DECT for the detection of metastases in the pelvic lymph nodes of rectal cancer patients and compare the findings to MRI and histopathology.

MATERIALS AND METHODS

The patients were referred to total mesorectal excision (TME) without any neoadjuvant oncological treatment. After surgery the rectum specimen was scanned, and lymph nodes were matched to the pathology report. Fifty-four histology proven rectal cancer patients received a pelvic DECT scan and a standard MRI. The Dual Energy CT quantitative parameters were analyzed: Water and Iodine concentration, Dual-Energy Ratio, Dual Energy Index, and Effective Z value, for the benign and malignant lymph node differentiation.

RESULTS

DECT scanning showed statistical difference between malignant and benign lymph nodes in the measurements of iodine concentration, Dual-Energy Ratio, Dual Energy Index, and Effective Z value. Dual energy CT classified 42% of the cases correctly according to N-stage compared to 40% for MRI.

CONCLUSION

This study showed statistical difference in several quantitative parameters between benign and malignant lymph nodes. There were no difference in the accuracy of lymph node staging between DECT and MRI.

Assessment and diagnostic accuracy of lymph node status to predict stage III colon cancer using computed tomography

Background

To study different imaging criteria for prediction of lymph node metastases (Stage III disease) in colon cancer using CT.

Methods

In a retrospective setting, 483 consecutive patients with histology proven colon cancer underwent elective primary resection during 2008–2011, a cohort of 119 patients were included. Contrast enhanced CT examinations, in portal-venous phase, were reviewed with assessment of the number of lymph nodes, their anatomical distribution, size, size ratio, internal heterogeneity, presence of irregular outer border and attenuation values. Sensitivity, specificity, PPV and NPV for each studied criteria for prediction of stage III disease was calculated.

Results

According to histopathology 80 patients were stage I-II and 39 were stage III. Of the studied CT-criteria for lymph node metastases per patient, internal heterogeneity in at least one lymph node resulted in the best performance with sensitivity, specificity, PPV and NPV of 79, 84, 70 and 89%, Odds ratio (OR) 20. Presence of irregular outer border resulted in a sensitivity, specificity, PPV and NPV of 59, 81, 61 and 82%, OR 6.2. If both internal heterogeneity and/or irregular outer border was used as a criterion this resulted in a sensitivity, specificity, PPV and NPV of 85, 75, 62 and 91%, OR 16.5. None of the size criteria used were predictive for stage III disease.

Conclusions

When performing preoperative CT in patients with colon cancer, the imaging criteria that allow best prediction of stage III disease on CT are either presence of at least one lymph node with internal heterogeneity or internal heterogeneity and/or irregular outer border. These criteria have to be validated in a prospective study.

Metabolic Tumor Volume and Total Lesion Glycolysis in PET/CT Correlate With the Pathological Findings of Colorectal Cancer and Allow Its Accurate Staging

INTRODUCTION

PET/CT plays an important role in cancer diagnosis. Recently, novel metabolic parameters in PET/CT such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG) have been reported to be diagnostic and prognostic biomarkers of various cancers. We evaluated the diagnostic value of these metabolic parameters in colorectal cancer (CRC).

METHODS

The study included 138 patients who underwent surgical resection of CRCs between August 2012 and March 2014. The MTVs and TLGs of tumors were measured using various SUV thresholds. The diagnostic abilities of the metabolic parameters were analyzed using ROC curves and classification and regression trees.

RESULTS

The AUCs of the MTVs and TLGs for predicting T stage (0.881-0.892) were significantly higher than the AUC of the SUVmax (0.824). In the M stage, the AUCs of MTVs and TLGs (0.688-0.723) were significantly higher than that of the SUVmax (0.606). Recursive partitioning applying classification and regression trees demonstrated that the optimal cutoff values of the most important variables for discriminating T, N, and M stages are MTV2.5 = 9.35 and 63.33 mL, TLG50% = 328.1, and TLG50% = 94.81, respectively.

CONCLUSION

Metabolic tumor volumes and TLGs in PET/CT are reliable diagnostic biomarkers. Using these parameters, more accurate preoperative diagnoses for CRC can be made.

Clinical evaluation of (18)F-fludeoxyglucose positron emission tomography/CT using point spread function reconstruction for nodal staging of colorectal cancer

OBJECTIVE

For patients with colorectal cancer, lymph node metastasis is a very important factor for prognostic and treatment determinations. Fluorine-18 fludeoxyglucose positron emission tomography/CT ((18)F-FDG-PET/CT) is among the useful tools for detecting lymph node metastasis. Recently, a new (18)F-FDG-PET/CT reconstruction technique for improving spatial resolution and signal-to-noise ratios, point spread function (PSF), has become available. We assessed the effect of PSF reconstruction on standardized uptake values and its diagnostic accuracy for lymph node staging in patients with colorectal cancer.

METHODS

We retrospectively analysed records from patients with colorectal cancer who underwent (18)F-FDG-PET/CT for pre-operative staging. All positron emission tomography CT (PET/CT) examinations were reconstructed using ordered subset expectation maximization (OSEM) and OSEM + PSF. We compared sensitivities, specificities, positive-predictive values (PPVs), negative-predictive values (NPVs) and accuracies of conventional PET/CT (reconstructed with OSEM) and PSF-PET/CT (reconstructed with OSEM + PSF) for identifying lymph node metastases. We also analysed the diagnostic confidence level on a 5-point scale.

RESULTS

With conventional PET/CT, the sensitivity, specificity, PPV, NPV and accuracy were 53.1%, 99.1%, 94.4%, 88.3% and 89.1%, respectively. With PSF PET/CT, the corresponding values were 65.6%, 99.1%, 95.4%, 91.2% and 91.8%, respectively. Conventional PET/CT and PSF PET/CT did not differ significantly in terms of N-stage definition (p = 0.125). However, the diagnostic confidence level of PSF PET/CT was significantly higher than that of conventional PET/CT (p < 0.01).

CONCLUSION

PSF reconstruction might slightly increase sensitivity without impairing specificity. Moreover, this technique is expected to facilitate more confident radiological decisions when compared with conventional PET/CT. Advance in knowledge: This study demonstrates the clinical effectiveness of PSF PET/CT for lymph node staging in colorectal cancer.

Accuracy of computed tomography in nodal staging of colon cancer patients

AIM

To predict node-positive disease in colon cancer using computed tomography (CT).

METHODS

American Joint Committee on Cancer stage I-III colon cancer patients who underwent curavtive-intent colectomy between 2007-2010 were identified at a single comprehensive cancer center. All patients had preoperative CT scans with original radiology reports from referring institutions. CT images underwent blinded secondary review by a surgeon and a dedicated abdominal radiologist at our institution to identify pericolonic lymph nodes (LNs). Comparison of outside CT reports to our independent imaging review was performed in order to highlight differences in detection in actual clinical practice. CT reviews were compared with final pathology. Results of the outside radiologist review, secondary radiologist review, and surgeon review were compared with the final pathologic exam to determine sensitivity, specificity, positive and negative predictive values, false positive and negative rates, and accuracy of each review. Exclusion criteria included evidence of metastatic disease on CT, rectal or appendiceal involvement, or absence of accompanying imaging from referring institutions.

RESULTS

From 2007 to 2010, 64 stageI-III colon cancer patients met the eligibility criteria of our study. The mean age of the cohort was 68 years, and 26 (41%) patients were male and 38 (59%) patients were female. On final pathology, 26 of 64 (40.6%) patients had node-positive (LN+) disease and 38 of 64 (59.4%) patients had node-negative (LN-) disease. Outside radiologic review demonstrated sensitivity of 54% (14 of 26 patients) and specificity of 66% (25 of 38 patients) in predicting LN+ disease, whereas secondary radiologist review demonstrated 88% (23 of 26) sensitivity and 58% (22 of 38) specificity. On surgeon review, sensitivity was 69% (18 of 26) with 66% specificity (25 of 38). Secondary radiology review demonstrated the highest accuracy (70%) and the lowest false negative rate (12%), compared to the surgeon review at 67% accuracy and 31% false negative rate and the outside radiology review at 61% accuracy and 46% false negative rate.

CONCLUSION

CT LN staging of colon cancer has moderate accuracy, with administration of NCT based on CT potentially resulting in overtreatment. Active search for LN+ may improve sensitivity at the cost of specificity.

Reliability of (18)f-fluorodeoxyglucose positron emission tomography/computed tomography in the nodal staging of colorectal cancer patients

Purpose

Lymph-node metastasis is considered as critical prognostic factor in colorectal cancer. A preoperative evaluation of lymph-node metastasis can also help to determine the range of distant lymph node dissection. However, the reliability of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in the detection of lymph-node metastasis is not fully known.

Methods

The medical records of 433 patients diagnosed with colorectal cancer were reviewed retrospectively. FDG-PET/CT and CT were performed on all patients. Lymph nodes were classified into regional and distant lymph nodes according to the American Joint Committee on Cancer (AJCC) Cancer Staging Manual, 7th edition.

Results

The patients included 231 males (53.3%) and 202 females (46.7%), with a mean age of 64.7 ± 19.0 years. For regional lymph nodes, the sensitivity of FDG-PET/CT was lower than that of CT (57.1% vs. 73.5%, P < 0.001). For distant lymph nodes, the sensitivity of FDG-PET/CT was higher than that of CT (64.7% vs. 52.9%, P = 0.012). The sensitivity of FDG-PET/CT for regional lymph nodes was higher in patients with larger primary tumors. The positivity of lymph-node metastasis for FDG-PET/CT was affected by carcinoembryonic antigen levels, tumor location, and cancer stage for regional lymph nodes and by age and cancer stage for distant lymph nodes (P < 0.05).

Conclusion

The sensitivity of FDG-PET/CT for regional lymph-node metastasis was not superior to that of CT. However, FDG-PET/CT provides helpful information for determining surgical plan especially in high risk patients group.

A scoring system to predict inferior mesenteric artery lymph node metastasis and prognostic value of its involvement in rectal cancer

PURPOSE

The aim of this study is to establish a prediction scoring system for inferior mesenteric artery (IMA) lymph node metastasis and to assess the prognostic impact of dissection of positive IMA node on patients with stage III rectal cancer.

METHODS

A retrospective study was performed in 264 patients with stage III rectal cancer undergoing curative surgery. Clinicopathological, survival, and recurrence data were compared between 29 patients with positive IMA nodes and 235 patients with negative IMA nodes. Clinicopathological data which were found to be significantly associated with IMA nodal status were incorporated into a scoring system.

RESULTS

In the training samples, tumor differentiation and preoperative serum CEA were significant predictors of IMA node metastasis in multivariate analysis, which were incorporated into a scoring system. Using receiver operating characteristic curve analysis, we determined a cutoff value of 46.5 for scores, at which the system's sensitivity was 86 % and specificity 61 %. When applied to testing sample, the sensitivity was 80 % and specificity 60 %. Survival analysis showed that 5-year disease-free survival rate (5-DFS) and 5-year overall survival (5-OS) in the positive IMA node group (24.4 and 27.6 %, respectively) were significantly lower than in the negative IMA node group (61.8 and 71.3 %, respectively) (P < 0.001). Furthermore, multivariate analysis indicated that IMA lymph node metastasis was an unfavorable independent prognostic factor for 5-DFS and 5-OS.

CONCLUSIONS

IMA lymph node metastasis is an independent poor prognostic factor for stage III rectal cancer. The prediction scoring system for IMA node metastasis would be beneficial in determining the appropriate level of IMA ligation.

Positron emission tomography/computed tomography for optimized colon cancer staging and follow up

OBJECTIVES

Optimal management of colon cancer (CC) requires detailed assessment of extent of disease. This study prospectively investigates the diagnostic accuracy of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (PET/CT) for staging and detection of recurrence in primary CC.

MATERIAL AND METHODS

PET/CT for preoperative staging was performed in 66 prospectively included patients with primary CC. Diagnostic accuracy for PET/CT and CT was analyzed. In addition to routine follow up, 42 stages I-III CC patients had postoperative PET/CT examinations every 6 months for 2 years. Serological levels of tissue inhibitor of metalloproteinase-1 (TIMP-1), carcinoembryonic antigen, and liberated domain I of urokinase plasminogen activator receptor were analyzed.

RESULTS

Accuracy for tumor, nodal, and metastases staging by PET/CT were 82% (95% confidence interval [CI]: 70; 91), 66% (CI: 51; 78), and 89% (CI: 79; 96); for CT the accuracy was 77% (CI: 64; 87), 60% (CI: 46; 73), and 69% (CI: 57; 80). Cumulative relapse incidences for stages I-III CC at 6, 12, 18, and 24 months were 7.1% (CI: 0; 15); 14.3% (CI: 4; 25); 19% (CI: 7; 31), and 21.4% (CI: 9; 34). PET/CT diagnosed all relapses detected during the first 2 years. High preoperative TIMP-1 levels were associated with significant hazards toward risk of recurrence and shorter overall survival.

CONCLUSIONS

This study indicates PET/CT as a valuable tool for staging and follow up in CC. TIMP-1 provided prognostic information potentially useful in selection of patients for intensive follow up.

The role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in the primary staging of rectal cancer

Background

In this study we aimed to determine the need for ¹⁸F-flourodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in the preoperative staging of rectal carcinoma in our large patient group according to level and location of tumor.

Method

Totally, 97 patients diagnosed with primary rectal adenocarcinoma between May 2009 and July 2011 were included in the study. Preoperative staging was performed by evaluating contrast-enhanced thoracic, abdominal, and pelvic computed tomographies. After staging by conventional methods, all patients underwent an ¹⁸F-FDG PET/CT. In all cases, the relationship between ¹⁸F-FDG uptake and gender, tumor height at the anal canal, localization in the rectal wall, plasma carcinoembryonic antigen levels, histopathological tumor type, and tumor stage were examined.

Results

While the ceCT was normal in 4 (4%) patients, it was positive for the rectum in 93 (95%), pelvic lymph nodes in 22 (22%), and distant metastases in 14 (14%) (liver (8), lung (8), bone (2), distant lymph nodes (6), and uterus (1)). Using computed tomography, disease stages were determined as stage 0, 1, 2, 3, and 4 in 4, 8, 48, 23, and 14 patients, respectively; ¹⁸F-FDG PET/CT was normal in two (2%) patients. The mean SUVmax of FDG-positive rectal tumors was calculated as 17.31 ± 9.37. Additionally, 18F-FDG uptake was seen in pelvic lymph nodes in 15 (15%) patients and in distant organs in 24 (24%) patients (liver (9), lung (12), bone (5), distant lymph nodes (11), uterus (1), and sigmoid colon (1)). According to an ¹⁸F-FDG PET/CT, 2, 7, 47, 20, and 21 patients were staged as stage 0, 1, 2, 3, and 4, respectively. In 14 patients (14.4%), the stage of the disease was either changed, and there was a need to make adjustments to the patient’s treatment strategy (n = 10), or the type of operation was changed (n = 4). In seven patients (0.7%), findings from ¹⁸F-FDG PET/CT images did not require any changes of the treatment plan.

Conclusion

F-FDG PET/CT provides new findings in addition to conventional techniques in the staging of primary rectal cancer. These findings could change the patients’ treatment strategies.

MR evaluation of rectal cancer: current concepts

Magnetic resonance imaging has become more frequently utilized for staging, preoperative planning, and post-neoadjuvant evaluation of rectal cancer. It offers detailed resolution of the layers of the rectal wall, visualization of the mesorectal fascia, and identification of locoregional nodal involvement. Many advances have been made since the original protocols and include the use of phased-array coils, orthogonally obtained images and 3-dimensional sequences, the use of diffusion-weighted and perfusion protocols to better evaluate the tumor before and after neoadjuvant therapy, and the development of techniques to better evaluate metastatic nodes. Magnetic resonance imaging shows similar accuracy to endorectal ultrasound when staging and offers a less invasive technique that is not limited by patient discomfort or decreased luminal size. This article is meant to provide an update on the recent advances in rectal cancer imaging while addressing the controversial issues that exist in staging, technique, and imaging protocol.

Role of positron emission tomography-computed tomography in gastrointestinal malignancies

Positron emission tomography (PET) has proved itself to be valuable in the evaluation of patients with a wide array of gastrointestinal (GI) malignancies. Subsequent development of fusion imaging with PET and computed tomography (PET-CT) scanners has significantly advanced the capabilities of imaging by combining the functional data of the(18)F-labeled glucose analogue fluorodeoxyglucose (FDG) with the conventional anatomic data provided by CT. This article reviews the evolving role of FDG PET-CT imaging in the initial assessment and monitoring of GI tumors. Specific applications are discussed, and normal variants and benign findings frequently encountered during PET-CT of the GI tract are reviewed.

Routine use of positron-emission tomography/computed tomography for staging of primary colorectal cancer: does it affect clinical management?

BACKGROUND

The use of positron emission tomography-computed tomography (PET/CT) for the preoperative staging of patients with colon and rectal cancer has increased steadily over the last decade. The aim of this study was to evaluate the effect of PET/CT on the preoperative staging and clinical management of patients with colorectal cancer.

METHODS

Between December 2010 and February 2012, 64 consecutive patients with colorectal cancer were evaluated with both PET/CT scans and conventional preoperative imaging studies. We prospectively recorded the medical reports of these patients. The PET/CT findings were compared with conventional imaging studies and the rate of over-staging or down-staging and changes in clinical management were evaluated. The correlation of the PET/CT with the conventional imaging was compared by a kappa agreement coefficient. Differences in the accuracy for N and T staging were assessed by χ2 and related-samples marginal homogeneity tests.

RESULTS

Thirty-nine (60.9%) patients had rectal cancer and 25 (39.1%) had colon cancer. Based on PET/CT, additional lesions were found in 6 (9.4%) of the patients: hilar and paratracheal lesions in 4 patients, hepatic in 1 and supraclavicular in 1 patient. In four of six patients, detailed imaging studies or biopsies revealed chronic inflammatory changes. Hepatic and supraclavicular involvement was confirmed in two patients. Therefore, the false positivity rate of PET/CT was 6.25%. Based on the additional PET/CT, 2 (3.2%) patients had a change in surgical management. A chemotherapy regimen was administered to the patient with a 1.5 cm hepatic metastasis near the right hepatic vein; for another patient with an identified supraclavicular lymph node metastasis, a simultaneous excision was performed.

CONCLUSIONS

Routine use of PET/CT for preoperative staging did not impact disease management for 96.8% of our patients. The results of our study conclude that PET/CT should not be routinely used for primary staging of colorectal cancer. More studies are required for identifying the subgroup of patients who might benefit from a PET/CT in their initial staging.

Lymphatic drainage of the rectum, preoperative assessment and its relevance to malignant polyp and rectal cancer management

SUMMARY The importance of lymph node metastasis in rectal cancer is well recognized with regards to prognosis, staging and treatment. Accurate staging is particularly important where neoadjuvant treatment has been shown to downsize and downstage locally advanced tumors. Vascular invasion, poor differentiation and increasing depth of invasion are related to a higher risk of lymph node metastasis in early cancers while advanced, poorly differentiated and low rectal cancers are more likely to have lateral pelvic sidewall nodal involvement. Nodal staging is crucial in the management of malignant rectal polyps, as is the deferral of surgery in patients who have a complete clinical and radiological response to chemoradiotherapy. In all of these situations nodal staging is vital and warrants ongoing evaluation to improve its accuracy.