Detection of recurrent and metastatic colorectal cancer: comparison of positron emission tomography and computed tomography

MRI VS. FDG-PET for diagnosis of response to neoadjuvant therapy in patients with locally advanced rectal cancer

Aim

In this study, we aimed to compare the diagnostic values of MRI and FDG-PET for the prediction of the response to neoadjuvant chemoradiotherapy (NACT) of patients with locally advanced Rectal cancer (RC).

Methods

Electronic databases, including PubMed, Embase, and the Cochrane library, were systematically searched through December 2021 for studies that investigated the diagnostic value of MRI and FDG-PET in the prediction of the response of patients with locally advanced RC to NACT. The quality of the included studies was assessed using QUADAS. The pooled sensitivity, specificity, positive and negative likelihood ratio (PLR and NLR), and the area under the ROC (AUC) of MRI and FDG-PET were calculated using a bivariate generalized linear mixed model, random-effects model, and hierarchical regression.

Results

A total number of 74 studies with recruited 4,105 locally advanced RC patients were included in this analysis. The pooled sensitivity, specificity, PLR, NLR, and AUC for MRI were 0.83 (95% CI: 0.77-0.88), 0.85 (95% CI: 0.79-0.89), 5.50 (95% CI: 4.11-7.35), 0.20 (95% CI: 0.14-0.27), and 0.91 (95% CI: 0.88-0.93), respectively. The summary sensitivity, specificity, PLR, NLR and AUC for FDG-PET were 0.81 (95% CI: 0.77-0.85), 0.75 (95% CI: 0.70-0.80), 3.29 (95% CI: 2.64-4.10), 0.25 (95% CI: 0.20-0.31), and 0.85 (95% CI: 0.82-0.88), respectively. Moreover, there were no significant differences between MRI and FDG-PET in sensitivity (P = 0.565), and NLR (P = 0.268), while the specificity (P = 0.006), PLR (P = 0.006), and AUC (P = 0.003) of MRI was higher than FDG-PET.

Conclusions

MRI might superior than FGD-PET for the prediction of the response of patients with locally advanced RC to NACT.

Radiologic Imaging Modalities for Colorectal Cancer

BACKGROUND

Studies reported various diagnostic value of radiologic imaging modalities for diagnosis and management of colorectal cancer (CRC).

AIMS

To summary the diagnosis and management of CRC using computed tomography colonography (CTC), magnetic resonance colonography (MRC), and positron emission tomography (PET)/computed tomography (CT).

METHODS

Comprehensive literature searches were conducted in PubMed, EmBase, and the Cochrane library for studies published before April 2021. The diagnostic performance of CTC, MRC, and PET/CT for CRC was summarized.

RESULTS

A total of 54 studies (17 studies for CTC, 8 studies for MRC, and 29 studies for PET/CT) were selected for final analysis. The sensitivity and specificity for CTC ranged from 27 to 100%, 88 to 100%, respectively, and the pooled sensitivity and specificity for CTC were 0.97 (95% CI 0.88-0.99) and 0.99 (95% CI 0.99-1.00). The sensitivity and specificity for MRC ranged from 48 to 100%, 60 to 100%, respectively, and the pooled sensitivity and specificity for MRC were 0.98 (95% C: 0.77-1.00) and 0.94 (95% CI 0.84-0.98). The sensitivity and specificity for PET/CT ranged from 84 to 100%, 33 to 100%, respectively, and the pooled sensitivity and specificity for PET/CT were 0.94 (95% CI 0.92-0.96) and 0.94 (95% CI 0.90-0.97). The area under the receiver operating characteristic curve for CTC, MRC, and PET/CT was 1.00 (95% CI 0.99-1.00), 0.99 (95% CI 0.98-1.00), and 0.97 (0.95% CI 0.95-0.98), respectively.

CONCLUSIONS

This study suggested both CTC and MRC with relative higher diagnostic value for diagnosing CRC, while PET/CT with higher diagnostic value in detecting local recurrence for patients with CRC.

Prognostic value of FDG PET-CT in suspected recurrence of colorectal carcinoma: survival outcomes of a 10-year follow-up : FDG PET in recurrent colorectal CA

OBJECTIVE

We aimed to evaluate the predictive value of FDG PET-CT scan and CEA measurements in recurrent colorectal cancer (CRC) patients.

METHODS

The records of 211 CRC patients who had FDG PET-CT scans between April 2009 and June 2011 due to suspicion of recurrence were extracted from the data of our previous report of 235 patients after 24 patients were excluded from the study due to lack of follow-up data or death unrelated to CRC. FDG PET-CT findings, simultaneous CEA levels, and survival data were evaluated retrospectively to determine the prognostic factors that affected the overall survival (OS) of the patients.

RESULTS

The mean age of 211 patients was 60.2 ± 12.8 years. The median follow-up time was 39 months (CI 95%: 4-123 months). The CRC-related death rate was 71.6% and the median OS time was measured 39 months (CI 95%: 27-50 months) for 211 patients. The median OS time for the patients with positive findings for recurrence in PET scans was 28 months (CI 95%: 22-33 months) which was significantly shorter (p < 0.001) than that of PET-negative patients (median OS was not reached; mean OS: 105 months; CI 95%: 95-116 months). CEA positivity also had a significant negative effect on survival (p < 0.001). Median OS times in patients with elevated and normal levels of CEA were 24 months (CI 95%: 17-30 months) and 85 months (CI 95%: 62-107 months), respectively. When the effect of CEA positivity was evaluated in patients with negative PET scans for recurrence, no statistically significant difference was determined (p = 0.209), but PET positivity had a significant negative effect on OS in patients with normal levels of CEA (p < 0.001). On the other hand, PET negativity had a significant positive effect on OS in patients with elevated CEA levels (p = 0.002). The extend of recurrent disease had also a significant effect on OS. The patients with distant metastasis had less favorable OS than those patients with only local recurrence (p < 0.001). The presence of liver metastasis also diminished the OS, but this effect was not statistically significant (p = 0.177).

CONCLUSION

FDG PET-CT scan which is a reliable imaging method to detect recurrence in CRC patients, regardless of CEA levels, can also provide valuable prognostic information, even superior to that of CEA measurement.

Pharmacokinetic Modeling of Targeted Ultrasound Contrast Agents for Quantitative Assessment of Anti-Angiogenic Therapy: a Longitudinal Case-Control Study in Colon Cancer

PURPOSE

To evaluate quantitative and semi-quantitative ultrasound molecular imaging (USMI) for antiangiogenic therapy monitoring in human colon cancer xenografts in mice.

PROCEDURES

Colon cancer was established in 17 mice by injection of LS174T (N_r = 9) or CT26 (N_n = 8) cancer cells to simulate clinical responders and non-responders, respectively. Antiangiogenic treatment (bevacizumab; N_rt = N_nt = 5) or control treatment (saline; N_rc = 4, N_nc = 3) was administered at days 0, 3, and 7. Three-dimensional USMI was performed by injection at days 0, 1, 3, 7, and 10 of microbubbles targeted to the vascular endothelial growth factor receptor 2 (VEGFR2). Microbubble binding rate (k_b), estimated by first-pass binding model fitting, and semi-quantitative parameters late enhancement (LE) and differential targeted enhancement (dTE) were compared at each day to evaluate their ability to assess and predict the response to therapy. Correlation analysis with the ex-vivo immunohistological quantification of VEGFR2 expression and the percentage blood vessel area was also performed.

RESULTS

Significant changes in the USMI parameters during treatment were observed only in the responders treated with bevacizumab (p-value < 0.05). Prediction of the response to therapy as early as 1 day after treatment was achieved by the quantitative parameter k_b (p-value < 0.01), earlier than possible by tumor volume quantification. USMI parameters could significantly distinguish between clinical responders and non-responders (p-value << 0.01) and correlated well with the ex-vivo quantification of VEGFR2 expression and the percentage blood vessels area (p-value << 0.01).

CONCLUSION

USMI (semi)quantitative parameters provide earlier assessment of the response to therapy compared to tumor volume, permit early prediction of non-responders, and correlate well with ex-vivo angiogenesis biomarkers.

FDG-PET/MRI in patients with pelvic recurrence of rectal cancer: first clinical experiences

OBJECTIVES

To determine the value of ¹⁸F-FDG-PET/MRI in the diagnosis and management of patients with pelvic recurrence of rectal cancer.

METHODS

Forty-four patients (16 women, 28 men) with a history of rectal cancer who received FDG-PET/MRI between June 2011 and February 2017 at our institution were retrospectively enrolled. Three patients received two FDG-PET/MRIs; thus a total of 47 examinations were included. Pelvic recurrence was confirmed either with histology (n = 27) or imaging follow-up (n = 17) (> 4 months). Two readers (one radiologist, one nuclear medicine physician) interpreted the images in consensus. Pelvic lesions were assessed regarding FDG uptake and morphology. Sensitivity, specificity, positive and negative predictive values as well as accuracy of PET/MRI in detecting recurrence were determined.

RESULTS

In 47 FDG-PET/MRIs 30 suspicious pelvic lesions were identified, 29 of which were malignant. Two patients underwent resection and had histologically proven pelvic recurrence without showing suspicious findings on FDG-PET/MRI. Changes in management due to FDG-PET/MRI findings had been implemented in eight patients. Eighty per cent (16/20) of resected patients had histologically negative resection margins (R0), one patient had uncertain resection margins. Sensitivity of FDG-PET/MRI in detecting recurrence was 94%, specificity 94%, positive/negative predictive value and accuracy were 97%, 90% and 94%, respectively.

CONCLUSIONS

FDG-PET/MRI is a valuable tool in the diagnosis and staging of pelvic recurrence in patients with rectal cancer.

KEY POINTS

• Metabolic information obtained from PET coupled with excellent soft tissue contrast from MRI could facilitate detection of rectal cancer recurrence and assist in treatment planning. • PET/MRI demonstrates high sensitivity and specificity for the diagnosis of local recurrence of rectal cancer • PET/MRI led to alterations in management in 18.2% of patients.

Diagnostic and prognostic value of preoperative 18F-fluorodeoxyglucose positron emission tomography/computed tomography for colorectal cancer: comparison with conventional computed tomography

BACKGROUND/AIMS

18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has been used for preoperative staging of colorectal cancer (CRC). However, the diagnostic accuracy of FDG-PET/CT for detection of lymph node or distant metastasis and its prognostic role have not been well established. We therefore evaluated the diagnostic and prognostic value of FDG-PET/CT in comparison with conventional CT for CRC.

METHODS

We investigated 220 patients who underwent preoperative FDG-PET/CT and CT, followed by curative surgery for CRC. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG-PET/CT and CT for detection of lymph node metastasis and distant metastasis were evaluated. In addition, we assessed the findings of FDG-PET/CT and CT according to outcomes, including cancer recurrence and cancer-related death, for evaluation of prognostic value.

RESULTS

For detection of lymph node metastasis, FDG-PET/CT had a sensitivity of 44%, a specificity of 84%, and an accuracy of 67%, compared with 59%, 65%, and 62%, respectively, for CT (P=0.029, P=0.000, and P=0.022). For distant metastasis, FDG-PET/CT had a sensitivity of 79%, a specificity of 94%, and an accuracy of 93%, compared with 79%, 87%, and 86%, respectively, for CT (P=1.000, P=0.004, and P=0.037). In addition, positive findings of lymph node metastasis and distant metastasis on FDG-PET/CT were associated significantly with cancer recurrence or cancer-related death (P=0.009, P=0.001, respectively).

CONCLUSIONS

Preoperative FDG-PET/CT had a higher specificity and accuracy compared to CT for detection of lymph node metastasis and distant metastasis of CRC. In addition, FDG-PET/CT could be a valuable prognostic tool for CRC.

Late sacral recurrence of rectal cancer treated by heavy ion radiotherapy: a case report

Background

The need for surveillance of rare late recurrence of rectal cancer has not yet been established. Local control of unresectable skeletal metastasis is important for palliation of symptoms and support for systemic chemotherapy.

Case presentation

A Japanese man underwent preoperative pelvic irradiation (50.4 Gy/28 Fr) and low anterior resection at the age of 57 years. The pathological stage was II (T3N0M0). Nine years after the surgery, his carcinoembryonic antigen (CEA) level showed rapid elevation, although he had no symptoms. A computed tomography (CT) scan showed no evidence of recurrent lesions, but positron emission tomography (PET)-CT revealed abnormally high 2-[¹⁸F]-fluoro-2-deoxy-d-glucose accumulation in the sacrum. A CT-guided needle biopsy confirmed the diagnosis of metastatic adenocarcinoma from the previous rectal cancer. The sacral metastasis reached the S1/S2 level and was considered inoperable. Conventional radiotherapy was also excluded due to the previous history of pelvic irradiation. Finally, heavy ion radiotherapy with carbon ions was performed as radical local therapy (70.4 GyE/16 Fr). The patient did not consent to systemic chemotherapy immediately after the irradiation. Five months after radiotherapy, multiple lung metastases were noted on CT, followed by mediastinal and hilar lymph node metastases. Systemic chemotherapy was started 9 months after the irradiation. During this time, the patient experienced some degree of pain and loss in muscle strength of the left lower limb, and a second heavy ion irradiation (60.0 GyE/12 Fr) was performed 11 months after the previous irradiation. After that, the sacral lesion has been stable and his symptoms have not worsened. Two years after the heavy ion therapy, the patient steadily continues outpatient chemotherapy and his quality of life is relatively maintained.

Conclusion

In case the risk of late recurrence is relatively high after rectal cancer surgery, clinicians should consider individual follow-up evaluations, including CEA measurements to allow for timely diagnosis and intervention. Heavy ion radiotherapy is effective for local control of sacral metastasis.

Evaluation of recurrent disease in the re-staging of colorectal cancer by 18F-FDG PET/CT: Use of CEA and CA 19-9 in patient selection

The aim of the present retrospective study was to evaluate the sensitivity and specificity of fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in assessing the recurrence of colorectal cancer (CRC) with regard to carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA 19-9). ¹⁸F-FDG PET/CT was performed in 100 patients for the re-staging of CRC. Therapy was discontinued prior to the examination. The mean (± standard deviation) CEA value (measured ~30 days prior to PET/CT examination) was 23.71 (±107) ng/ml, whereas the CA 19-9 value was 72 (±190.3) U/ml. Differences in CEA and CA 19-9 values in patients with scans that were positive or negative for recurrence were analyzed by means of a receiver operating characteristic (ROC) curve. ROC curves were used for the calculation of the sensitivity and specificity of ¹⁸F-FDG PET/CT for the CEA and CA 19-9 levels. The results of the ¹⁸F-FDG PET/CT were found to be associated with the CEA level (P=0.001), but not with the CA 19-9 level (P=0.43). PET/CT was positive for recurrence in 60 patients (60.0%), whose mean CEA and CA 19-9 values were 33.07±136.7 ng/ml and 75.24±192.3 U/ml, respectively. PET/CT was negative for recurrence in 40 patients (40.0%), whose mean CEA and CA 19-9 values were 10.15±30 ng/ml and 67.76±190 U/ml, respectively. On the basis of ROC curve analysis, the best compromise between sensitivity and specificity was achieved for CEA levels of 3.5 ng/ml [sensitivity, 80%; 95% confidence interval (CI), 67-89%; and specificity, 60%; 95% CI, 45-78%]. The study concluded that the detection of recurrence by ¹⁸F-FDG PET/CT in patients treated for CRC is associated with CEA, but not CA 19-9 serum levels. Moreover, ¹⁸F-FDG PET/CT should be recommended in patients with suspected CRC recurrence even when they present with CEA levels below the normal cut-off.

Positron Emission Tomography–Computed Tomography (PET-CT) Versus No PET-CT in the Management of Potentially Resectable Colorectal Cancer Liver Metastases: Cost Implications of a Randomized Controlled Trial

Purpose:

To evaluate whether positron emission tomography (PET) combined with computed tomography (PET-CT) is cost saving, or cost neutral, compared with conventional imaging in management of patients with resectable colorectal cancer liver metastases.

Methods:

Cost evaluation of a randomized trial that compared the effect of PET-CT on surgical management of patients with resectable colorectal cancer liver metastases. Health care use data ≤ 1 year after random assignment was obtained from administrative databases. Cost analysis was undertaken from the perspective of a third-party payer (ie, Ministry of Health). Mean costs with 95% credible intervals (CrI) were estimated by using a Bayesian approach.

Results:

The estimated mean cost per patient in the 263 patients who underwent PET-CT was $45,454 CAD (range, $1,340 to $181,420) and in the 134 control patients, $40,859 CAD (range, $279 to $293,558), with a net difference of $4,327 CAD (95% CrI, −$2,207 to $10,614). The primary cost driver was hospitalization for liver surgery (difference of $2,997 CAD for PET-CT; 95% CrI, −$2,144 to $8,010), which was mainly a result of a longer length of hospital stay for the PET-CT arm (median, 7 v 6 days; P = .03) and a higher postoperative complication rate (20% v 10%; P = .01). Baseline characteristics were similar between groups, including the number of liver segments involved with cancer, number of segments resected, and type of liver resection performed. No difference in survival was detected between arms.

Conclusion:

PET-CT was associated with limited clinical benefit and a nonsignificant increased cost. Universal funding of PET-CT in the management of patients with resectable colorectal cancer liver metastases does not seem justified.

Added value of arterial enhancement fraction color maps for the characterization of small hepatic low-attenuating lesions in patients with colorectal cancer

OBJECTIVE

To assess the added value of arterial enhancement fraction (AEF) color maps for the differentiation of small metastases from hepatic benign lesions.

SUBJECTS AND METHODS

We retrospectively analyzed 46 patients with colorectal cancer who underwent multiphasic liver CT imaging and had low-attenuating liver lesions smaller than 3 cm (123 total lesions; metastasis: benign = 32:91). AEF color maps of the liver were created from multiphasic liver CT images using dedicated software. Two radiologists independently reviewed multiphasic CT image sets alone and in combination with image sets with AEF color maps using a five-point scale. The additional diagnostic value of the color maps was assessed by means of receiver-operating characteristic (ROC) analysis.

RESULTS

The area under the ROC curve (Az) increased when multiphasic CT images were combined with AEF color map analysis as compared with evaluation based only on multiphasic CT images (from 0.698 to 0.897 for reader 1, and from 0.825 to 0.945 for reader 2; P < 0.001 and 0.002, respectively). The increase Az was especially significant for lesions less than 1 cm (from 0.702 to 0.888 for reader 1, and from 0.768 to 0.958 for reader 2; P = 0.001 and P = 0.001, respectively). The mean AEF of tumor-adjacent parenchyma (35.07 ± 27.2) was significantly higher than that of tumor-free liver parenchyma (27.3 ± 20.6) (P = 0.04).

CONCLUSIONS

AEF color mapping can improve the diagnostic performance for small hepatic metastases from colorectal cancer and may allow for the elimination of additional examinations.

Value of CT, FDG PET-CT and serum tumor markers in staging recurrent colorectal cancer

BACKGROUND

Serum tumor markers and computed tomography (CT) are the most widely accepted monitoring tools for the follow-up patients with colorectal cancer (CRC). Positron emission tomography (PET) with 18[F]-fluorodeoxyglucose (FDG) is a promising modality for the evaluation of recurrent CRC. The purpose of this study was to (1) investigate the sensitivity and specificity of serum tumor marker assay, CT and FDG PET-CT, (2) determine the correlation of these markers with FDG PET-CT quantitative indices such as maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) in patients suspected to have recurrent CRC.

PATIENTS

FDG PET-CT imaging was performed in 212 patients with possible CRC recurrence. A retrospective study was performed on patients with (1) a history of CRC with complete remission after treatment, (2) pathology of adenocarcinoma and (3) increase in cancer antigen 19-9 (CA 19-9) and/or carcinoembryonic antigen (CEA) or suspicious radiological evaluation during follow-up after complete remission.

METHODS

All patients underwent integrated FDG PET-CT scan. Serum tumor markers were obtained within 3 months of PET-CT. All enrolled cases showed increase in a tumor marker over the reference value on at least two serial measurements or abnormal CT scan before PET-CT was performed. Results were compared with histopathological findings or clinical follow-up.

RESULTS

Following exclusion of 57 patients with missing data or lost to follow-up, 155 patients (87 men, mean age: 61 years) remained for final analysis. Serum CEA and CA 19-9 had a sensitivity of 74 and 35% and specificity of 86 and 83% for the detection recurrent CRC, respectively. The sensitivities of CT and FDG PET-CT were 79 and 92% and specificities were 45 and 100%, respectively. At an adaptive threshold of 42%, the median SUVmax, SUVmean, MTV and TLG of these lesions were 8.8, 5.2, 11.3 cm[Formula: see text] and 55.4, respectively. All FDG PET-CT quantitative parameters correlated positively with serum CEA levels, and the correlation coefficients were 0.45, 0.44 and 0.49 for SUVmax, MTV and TLG [Formula: see text].

CONCLUSION

PET-CT scan, CEA and CA-19-9 results were correlated. However, both tumor markers had poor sensitivity to detect metastatic disease. PET-CT is more accurate than CT in detecting recurrent CRC in this study. Majority of the recurrences were in the liver and the sensitivity is affected by tumor histology. The correlation between semiquantitative FDG PET parameters and serum tumor marker levels is moderate.

Current status of imaging and emerging techniques to evaluate liver metastases from colorectal carcinoma

Colorectal cancer is the third most common cancer diagnosed in both men and women in the United States. Liver is a common site of tumor spread and in approximately 30% of the cases; synchronous liver disease is present at the time of diagnosis. Early detection of liver metastases is crucial to appropriately select patients who may benefit from hepatic resection among those needing chemotherapy, to improve 5-year survival. Advances in imaging techniques have contributed greatly to the management of these patients. Multidetector computed tomography is the most useful test for initial staging and in posttreatment surveillance settings. Magnetic resonance imaging is considered superior to multidetector computed tomography and positron emission tomography for the detection and characterization of small lesions and for liver evaluation in the presence of background fatty liver changes. Positron emission tomography-computed tomography has a problem-solving role in the detection of distant metastasis and in posttreatment evaluation. The advanced imaging methods also serve a role in selecting appropriate patients for radiologically targeted therapies and in monitoring response to conventional and novel therapies.

Clinical application of 18F-fluorodeoxyglucose positron emission tomography for assessment and evaluation after therapy for malignant hepatic tumor

Positron emission tomography (PET) is widely available and its application with 2-[(18)F] fluoro-2-deoxy-D-glucose ((18)F-FDG) in oncology has become one of the standard imaging modalities in diagnosing and staging of tumors, and monitoring the therapeutic efficacy in hepatic malignancies. Recently, investigators have measured glucose utilization in liver tumors using (18)F-FDG and positron emission tomography/computer tomography (PET/CT) in order to establish a diagnosis of tumors, assess their biologic characteristics and predict therapeutic effects on hepatic malignancies. The PET/CT with (18)F-FDG may further enhance the hepatic malignancy diagnostic algorithm by accurate diagnosis, staging, restaging and evaluating its biological characteristics, which can benefit the patients suffering from primary and metastatic hepatic tumors such as hepatocellular carcinoma (HCC), cholangiocarcinoma (CCC), and metastatic liver tumor.

Unnecessary surgery can be avoided by judicious use of PET/CT scanning in colorectal cancer patients

AIM

This study aims to determine the role of positron emission tomography (PET)/computed tomography (CT) in changing the management plan in patients with metastatic or recurrent colorectal cancer (CRC) and to evaluate the role of PET/CT in patients with an unexplained rise in carcinoembryonic antigen (CEA).

MATERIALS AND METHODS

A total of 60 consecutive patients with CRC, who had PET/CT, were identified between 2008 and 2010. All patients had CT scans prior to the PET/CT. Data were collected from clinic letters, CT and PET CT reports and pathology results and cross-checked with the patient's notes.

RESULTS

Patients were aged between 43 and 85 years [33 males, 27 females]. CEA was raised in 37 patients and normal in 23. Results of PET/CT were compared with that of CT scan and 33 out of the 60 patients (55%) had PET/CT results which were different to that of CT scan and 27 patients (45%) had similar PET/CT and CT results. PET scan appropriately altered the management in 23/60 patients (38%) and avoided unnecessary surgery in 14 patients. PET/CT had a sensitivity of 86% and specificity of 84%. In patients with an unexplained rise in CEA, PET/CT was positive in only one out of ten (10%) patients.

CONCLUSION

PET/CT is valuable in deciding the management outcome in patients with metastatic or recurrent colorectal cancer. Unnecessary surgery might be avoided by careful use of PET/CT scanning in colorectal cancer patients. PET/CT might not be of value in patients with an unexplained rise in CEA.

The utility of FDG-PET/CT as an effective tool for detecting recurrent colorectal cancer regardless of serum CEA levels

PURPOSE

Tumor recurrence of colorectal cancers (CRC) is generally followed up by analyses of the serum carcinoembryonic antigen (CEA) levels. However, recent evidence suggests that tumor recurrence can also be visualized by 18F-fluoro-deoxyglucose emission tomography/computed tomography (FDG-PET/CT) in patients with normal CEA levels. We retrospectively evaluated the diagnostic performance of FDG-PET/CT in patients with suspected recurrence of CRC by comparing PET/CT performance in patients with normal CEA levels with PET/CT performance in patients with elevated CEA levels.

METHODS

A total of 235 patients with CRC who had been treated with surgery and/or chemotherapy/radiotherapy underwent PET/CT for the detection of tumor recurrence. The patients [96 females and 139 males; age (mean ± SD) 59.9 ± 12.6 years; range 18-85] were divided into 2 groups based on whether their CEA levels were normal (<5 ng/ml) (Group 1, n = 118) or elevated (>5 ng/ml) (Group 2, n = 117). All of the patients had suspected recurrence based on raised CEA levels, clinical symptoms, and/or tumor detection using other imaging modalities.

RESULTS

Of the 235 patients, 172 (73.1 %) had disease recurrence confirmed by a pathological examination (either biopsy or surgical exploration) or clinical follow-up studies. The FDG-PET/CT study yielded a true positive in detecting recurrence in 169 (71.9 %) patients, a true negative in 53 (22.5 %) patients, a false negative in 3 (1.2 %) patients and a false positive in 10 (4.2 %) patients. CRC recurrence was detected in 64.4 % (76/118) and 88 % (103/117) patients in Group 1 and Group 2 with FDG-PET/CT, respectively. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of the FDG-PET/CT study for establishing recurrence were 100, 84, 89.4, 100 and 93.2 %, respectively, for Group 1; by contrast, these parameters were 97.1, 84.6, 98, 78.5 and 95.7 %, respectively, for Group 2. The number of patients with hepatic and extra-hepatic metastases, such as lung and abdominal lymph node metastasis, detected with FDG-PET/CT was significantly different in Group 1 than in Group 2; however, the number of patients with local recurrence and peritoneal implants detected with FDG-PET/CT was not different between the two groups.

CONCLUSIONS

FDG-PET/CT can accurately detect tumor recurrence in patients with suspected recurrent CRC, even for patients with normal CEA levels.

Pelvic colorectal recurrence: crucial role of radiologists in oncologic and surgical treatment options

Radical resection is the only potential cure for patients with locally advanced primary and recurrent rectal cancer and is considered curative only when the histologic margins are clear of tumour. Early diagnosis of the disease is essential as it increases the likelihood of a potentially curative resection and prevention of dissemination. Clinical examination, tumour markers and radiologic modalities such as ultrasonography, computed tomography, magnetic resonance imaging and positron emission tomography are routinely used in an effort to accurately stage these patients and provide useful information for the selection of patients for further treatment/management. This review describes the methods of staging patients with locally advanced primary and recurrent rectal cancer prior to surgery emphasizing the role that radiologists have in this process.

Colorectal cancer - patterns of locoregional recurrence and distant metastases as demonstrated by FDG PET / CT

Colorectal cancer (CRC) can recur locoregionally or at distant sites. Timely diagnosis of recurrence is of paramount importance, as radical treatment of the localized disease can prolong survival. Fluorodeoxyglucose positron emission tomography / computed tomography (PET / CT) is routinely used in restaging and surveillance of colorectal cancer, as it can demonstrate recurrent disease with good accuracy. This article illustrates the spectrum of standard as well as unusual patterns of local recurrence and distant metastases of colorectal cancer.

Could the serial determination of Ca15.3 serum improve the diagnostic accuracy of PET/CT?: results from small population with previous breast cancer

OBJECTIVES

A single value of tumor marker elevation is not used for the diagnosis of breast cancer (BC) relapse, whereas the serial measurements which confirm a persistent Ca15.3 increase can represent an early signal of tumor relapse, even if described in asymptomatic patients without any other clinical or instrumental signs of cancer. The aim of this study was to assess the relationship between serial measures of Ca15.3 and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) findings in patients with already treated BC during follow-up.

METHODS

We retrospectively selected 60 patients (mean age 62 ± 11 years) with previous history of BC, already treated with surgery and other treatments. Three serial measures of Ca15.3 were collected within 1 year before PET/CT examination, respectively, at 12-9 months (297 ± 30 days), 9-3 months (154 ± 51 days) and 3-0 months (46 ± 28 days). Clinical outcome or imaging follow-up data were used to define disease relapse. The increase in tumor marker value was compared with PET/CT results and disease relapse. Coefficient of variation (CV) and ROC curves were used. Disease-free survival (DFS) curves were computed by Kaplan-Meier method.

RESULTS

PET/CT was negative in 36 (60%) and positive in 24 (40%) patients. The median time between initial treatment and PET/CT was 3 years. CV of the Ca15.3 serial determinations was significantly higher in patients with positive than negative PET/CT (39 vs. 24%, p < 0.05). Disease relapse was found in 25 (42%) patients, of these 21 (88%) had positive PET/CT. ROC analyses showed that an increase of Ca15.3 between the 2nd and 3rd measures have better individuated positive PET/CT and disease relapse (AUC 0.65 and 0.64, respectively; p < 0.05). DFS was higher in patients with negative than positive PET/CT (65 vs. 15%, p < 0.05).

CONCLUSIONS

Serial increase of Ca15.3 could be considered optimal to address FDG PET/CT examination during BC patients follow-up. PET/CT performed just on time might allow, earlier and with higher diagnostic accuracy, the detection of disease relapse in BC patients.

Diffusion-weighted MRI and liver metastases

Liver metastases are the most frequently encountered malignant liver lesions in the Western countries. Accurate diagnosis of liver metastases is essential for appropriate management of these patients. Multiple imaging modalities, including ultrasound, CT, positron emission tomography, and MRI, are available for the evaluation of patients with suspected or known liver metastases. Contrast-enhanced MRI has a high accuracy for detection and characterization of liver lesions. Additionally, diffusion-weighted MRI (DWI) has been gaining increasing attention. It is a noncontrast technique that is easy to perform, could be incorporated in routine clinical protocols, and has the potential to provide tissue characterization. This article discusses the basic principles of DWI and discusses its emerging role in the detection of liver metastases in patients with extrahepatic malignancies.

What is the most accurate whole-body imaging modality for assessment of local and distant recurrent disease in colorectal cancer? A meta-analysis : imaging for recurrent colorectal cancer

PURPOSE

The objective of this study was to compare the diagnostic performance of positron emission tomography (PET), PET/CT, CT and MRI as whole-body imaging modalities for the detection of local and/or distant recurrent disease in colorectal cancer (CRC) patients who have a (high) suspicion of recurrent disease, based on clinical findings or rise in carcinoembryonic antigen (CEA).

METHODS

A meta-analysis was undertaken. PubMed and Embase were searched for studies on the accuracy of whole-body imaging for patients with suspected local and/or distant recurrence of their CRC. Additionally, studies had to have included at least 20 patients with CRC and 2 × 2 contingency tables had to be provided or derivable. Articles evaluating only local recurrence or liver metastasis were excluded. Summary receiver-operating characteristic (ROC) curves were constructed from the data on sensitivity and specificity of individual studies and pooled estimates of diagnostic odds ratios (DORs) and areas under the ROC curve (AUCs) were calculated. To test for heterogeneity the Cochran Q test was used.

RESULTS

Fourteen observational studies were included which evaluated PET, PET/CT, CT and/or MRI. Study results were available in 12 studies for PET, in 5 studies for CT, in 5 studies for PET/CT and in 1 study for MRI. AUCs for PET, PET/CT and CT were 0.94 (0.90-0.97), 0.94 (0.87-0.98) and 0.83 (0.72-0.90), respectively. In patient based analyses PET/CT had a higher diagnostic performance than PET with an AUC of 0.95 (0.89-0.97) for PET/CT vs 0.92 (0.86-0.96) for PET.

CONCLUSION

Both whole-body PET and PET/CT are very accurate for the detection of local and/or distant recurrent disease in CRC patients with a (high) suspicion of recurrent disease. CT has the lowest diagnostic performance. This difference is probably mainly due to the lower accuracy of CT for detection of extrahepatic metastases (including local recurrence). For clinical practice PET/CT might be the modality of choice when evaluating patients with a (high) suspicion of recurrent disease, because of its best performance in patient based analyses and confident prediction of disease status.

FDG PET/CT evaluation of treatment response in patients with recurrent colorectal cancer

AIM

to evaluate the treatment response in patients with recurrent colorectal cancer (CRC) using FDG PET/CT.

MATERIALS AND METHODS

a total of 32 recurrent CRC patients (21 males, 11 females; mean age, 52.8 years) were included in this retrospective study. All patients underwent a baseline and follow-up FDG PET/CT scans after chemotherapy. Of 32 patients, 23 patients had follow-up carcinoembryonic antigen (CEA) levels.

RESULTS

on qualitative analysis of baseline and follow-up FDG PET/CT studies, there were 20 nonresponders and 12 were responders. On quantitative analysis, there were 19 nonresponders and 13 were responders. In responders, baseline and follow-up mean SUV(max) were 11.8 ± 10.1 and 3.7 ± 4.1, respectively (significant decrease, P = 0.001). Among nonresponders, baseline and follow-up mean SUV(max) were 8.1 ± 5.2 and 14.1 ± 9.0, respectively (significant increase, P = 0.003). There was no association between response and different factors like age, sex, diagnosis, extent of the lesions, and number of lesions.

CONCLUSION

FDG PET/CT appears to be useful modality in evaluating chemotherapy response and can differentiate responders from nonresponders in recurrent CRC patients.

Progress in metastatic colorectal cancer: growing role of cetuximab to optimize clinical outcome

The prognosis of metastatic colorectal cancer remains poor despite advances made in recent years, particularly with new treatments directed towards molecular targets. Cetuximab, a chimeric immunoglobulin (Ig)G1 monoclonal antibody that targets the ligand-binding domain of the epidermal growth factor receptor (EGFR), is active in metastatic colorectal cancer. As an IgG1 antibody, cetuximab may exert its antitumour efficacy through both EGFR antagonism and antibody-dependent cell-mediated cytotoxicity. The benefits of cetuximab in metastatic colorectal cancer are well documented in clinical trials and are acknowledged in the approval and licensing of this agent. There is evidence of the role of cetuximab not only in irinotecan-refractory or heavily pretreated patients, but also of the efficacy and safety of the addition of this agent to FOLFIRI (irinotecan/5-fluorouracil/leucovorin) in first-line metastatic colorectal cancer, with an enhanced effect in 5-fluorouracil patients with Kirsten rat sarcoma (KRAS) wild-type tumours. In these patients, a recent meta-analysis of the pooled Cetuximab Combined with Irinotecan in First-Line Therapy for Metastatic Colorectal Cancer (CRYSTAL) and Oxaliplatin and Cetuximab in First-Line Treatment of mCRC (OPUS) patient populations confirms that the addition of cetuximab to first-line chemotherapy achieves a statistically significant improvement in the best overall response, overall survival time, and progression-free survival (PSF) compared with chemotherapy alone. In nonresectable colorectal liver metastases, cetuximab plus FOLFOX-6 (oxaliplatin/5-fluorouracil/leucovorin) or cetuximab plus FOLFIRI increased significantly resectability of liver metastases, including R0 resections. Also, preliminary data indicate that cetuximab can be administered in a more convenient 2-week schedule in combination with standard chemotherapy. Cetuximab is generally well tolerated. Acne-form rash is the most frequent toxicity. Up to the present time, the results obtained with targeted therapy combinations are not as encouraging as initially expected. The identification of biomarkers associated with disease control, including KRAS and BRAF mutation status in patients treated with cetuximab, is changing the current management of metastatic colorectal cancer. Clinical and molecular predictive markers of response are under active evaluation in order to better select patients who could benefit from cetuximab treatment, with the aim of both optimising patient outcomes and avoiding unnecessary toxicities.

18F-FDG PET/CT imaging in oncology

Accurate diagnosis and staging are essential for the optimal management of cancer patients. Positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro-D-glucose integrated with computed tomography (18F-FDG PET/CT) has emerged as a powerful imaging tool for the detection of various cancers. The combined acquisition of PET and CT has synergistic advantages over PET or CT alone and minimizes their individual limitations. It is a valuable tool for staging and restaging of some tumors and has an important role in the detection of recurrence in asymptomatic patients with rising tumor marker levels and patients with negative or equivocal findings on conventional imaging techniques. It also allows for monitoring response to therapy and permitting timely modification of therapeutic regimens. In about 27% of the patients, the course of management is changed. This review provides guidance for oncologists/radiotherapists and clinical and surgical specialists on the use of 18F-FDG PET/CT in oncology.

FDG PET and PET/CT for colorectal cancer

The evaluation of patients with known or suspected recurrent colorectal carcinoma is now an accepted indication for positron emission tomography using (18)F-fluorodeoxyglucose (FDG-PET) imaging. PET and CT are complimentary, and therefore, integrated PET/CT imaging should be performed where available. FDG-PET/CT is indicated as the initial test for diagnosis and staging of recurrence, and for preoperative staging (N and M) of known recurrence that is considered to be resectable. FDG-PET imaging is valuable for the differentiation of posttreatment changes from recurrent tumor, differentiation of benign from malignant lesions (indeterminate lymph nodes, hepatic, and pulmonary lesions), and the evaluation of patients with rising tumor markers in the absence of a known source. The addition of FDG-PET/CT to the evaluation of these patients reduces overall treatment costs by accurately identifying patients who will and will not benefit from surgical procedures. This new powerful technology provides more accurate interpretation of both CT and FDG-PET images and therefore more optimal patient care. PET/CT fusion images affect the clinical management by guiding further procedures (biopsy, surgery, and radiation therapy), excluding the need for additional procedures, and changing both inter- and intramodality therapy.

PET/CT today and tomorrow in veterinary cancer diagnosis and monitoring: fundamentals, early results and future perspectives

Functional imaging using positron emission tomography (PET) plays an important role in the diagnosis, staging, image-guided treatment planning and monitoring of malignant diseases. PET imaging complements conventional anatomical imaging such as computed tomography (CT) and magnetic resonance imaging (MRI). The strength of CT scanning lies in its high spatial resolution, allowing for anatomical characterization of disease. PET imaging, however, moves beyond anatomy and characterizes tissue based on functions such as metabolic rate. Combined PET/CT scanners were introduced commercially in 2001 and a number of technological advancements have since occurred. Radiolabelled tracers such as (18)F-fluorodeoxyglucose (FDG) and (18)F-fluorothymidine (FLT) allow visualization of various metabolic processes within cancer cells. Many studies in human oncology evaluating the utility of PET/CT have demonstrated clinical benefits. Few veterinary studies have been performed, but initial studies show promise for improved detection of malignancy, more thorough staging of canine cancer and determination of early response and disease recrudescence.

Role of FDG-PET/CT in detection of recurrent disease in colorectal cancer

BACKGROUND

One-third of patients with colorectal cancer (CRC) are likely to have a recurrence within the first 1-2 years. Conventional imaging modalities have limitations in detecting recurrent disease early. The purpose of this study was to assess the usefulness of fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in the detection of recurrence in patients with CRCs.

METHODS

One hundred and eighty-three patients, who were earlier treated with surgery and/or chemotherapy/radiotherapy, underwent 269 PET/CT studies for the detection of recurrence. The final diagnosis was made on the basis of histological analysis or clinical and imaging follow-up.

RESULTS

The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value in detecting recurrent CRC using F-FDG-PET/CT were 87, 90, 88, 93, and 80%, respectively. PET/CT was found to have limitations in detecting microscopic disease and small-sized lesions. The common cause of false-positive PET/CT results was infective and inflammatory pathology in our setup.

CONCLUSION

PET/CT showed high sensitivity, specificity, and accuracy for the detection of recurrent disease in patients, who were earlier treated for CRC. PET/CT can be considered as a useful diagnostic tool in these patients.

Fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography predicts extrahepatic metastatic potential of colorectal metastasis: a practical guide for yttrium-90 microsphere liver-directed therapy

The objective of this retrospective study was to assess the likelihood of extrahepatic metastases based on tumor metabolic load index (TMLI) for patients with colorectal liver metastases to determine the potential intermediate endpoint of yttrium-90 (Y-90) microsphere liver-directed therapy. Forty-eight (48) patients with colorectal metastatic cancer of the liver who were referred for Y-90 microsphere therapy and F-18 fluoro-2-deoxy-D-glucose positron emission tomography (PET) imaging were included. All patients had baseline computed tomography, hepatic angiography, and planning intra-arterial technetium-99m macro-aggregated albumin scans. Pretreatment PET images were analyzed by visual inspection of extrahepatic metastases and by computer quantification of total liver tumor metabolism. For each patient, regions of interest were drawn along the liver edge to measure total liver standard uptake value on axial images, covering the entire span of the liver. The total liver standard uptake value was then converted by logarithm in equivalent volumes of liver mass to obtain TMLI for comparison. A Levene test for equality of variances and t-tests were used for comparing pretreatment TMLIs of patients with or without extrahepatic metastasis. Discriminant and receiver operating characteristic (ROC) analyses were used to obtain a cutoff value with highest specificity in predicting negative extrahepatic metastasis. There were 21 and 27 patients identified as negative and positive for extrahepatic metastasis, respectively. The TMLI of the group with negative extrahepatic metastasis was significantly lower than that with positive extrahepatic metastasis (10.22 + 0.32 versus 10.74 + 0.57, p < 0.0005). The cutoff TMLI with 100% specificity was found to be 10.65. There was a significant difference in liver tumor load with respect to the presence or absence of an extrahepatic metastatic tumor as evaluated objectively with PET. This leads to the identification of TMLI threshold, below which extrahepatic metastases are unlikely and thus may provide guidance for Y-90 therapy.

Radioembolization of liver tumors with yttrium-90 microspheres

Radioembolization (RE), also termed selective internal radiation therapy (SIRT), has been gradually introduced to the clinical arsenal of cytoreductive modalities in recent years. There is growing evidence for efficiency in liver tumors of various entities, with the most prominent ones being hepatocellular carcinoma, colorectal cancer, and neuroendocrine tumors. Hepatic metastases of numerous other tumor entities including breast cancer, cholangiocarcinoma, and pancreatic cancer are treatment-sensitive, even when being refractory to other treatment modalities such as bland-embolization, regional, or systemic chemotherapy. The antitumor effect of SIRT is related to radiation rather than embolization, with extraordinary high local radiation doses obtained selectively at the site of viable tumor and little affection of the surrounding normal liver tissue. Morphologic changes after RE may pose difficulties for interpretation in conventional restaging with regard to tumor viability and true response to treatment. Therefore, functional imaging, that is, metabolic imaging with (18)F fluorodeoxyglucose positron emission tomography (computed tomography) in the majority of treated tumors, is regarded the gold standard in this respect and should be included for pre- and post-SIRT assessment. To prevent serious toxicity to be associated with the potent antitumor efficacy, meticulous pretreatment evaluation is of particular importance. Improvements in predicting dosimetry will help optimize treatment and patient selection. Nuclear medicine procedures are essential for planning, performing, and monitoring of RE. However, the interdisciplinary aspect of patient management has to be emphasized for this particular treatment form. As SIRT is moving forward from the salvage setting indication to the use in earlier stages of hepatic tumor disease and with the advent of new treatment protocols and targeted therapies, embedding SIRT into a multidisciplinary approach will become even more important. This article focuses on procedural and technical aspects for selection, preparation, and performance of treatment as well as post-therapeutic monitoring and response assessment.

Assessment of tumor recurrence in patients with colorectal cancer and elevated carcinoembryonic antigen level: FDG PET/CT versus contrast-enhanced 64-MDCT of the chest and abdomen

OBJECTIVE

The purpose of this study was to compare FDG PET/CT and contrast-enhanced 64-MDCT of the chest, abdomen, and pelvis in the detection of tumor recurrence in patients with colorectal cancer and an elevated level of carcinoembryonic antigen (CEA).

MATERIALS AND METHODS

A retrospective analysis included 50 patients (31 men, 19 women; mean age, 61 years; range, 28-89 years) with 55 clinical events of elevated or increasing CEA level who underwent FDG PET/CT and MDCT for suspected tumor recurrence.

RESULTS

Recurrent or metastatic disease was found in 36 of 55 events (65.5%) of elevated CEA. Fifty-four of 61 tumor sites suspected as tumor recurrence with any imaging technique were found to be local recurrence or metastatic colorectal cancer at final analysis. The other seven sites were one separate malignant tumor (small lymphocytic lymphoma) and six benign lesions. Diagnosis was based on histopathologic findings (n = 27) or clinical and imaging findings (n = 35) during a median follow-up period of 12 months (range, 6-31 months). One site of tumor recurrence was missed prospectively at both MDCT and PET/CT. On an event-based analysis, the sensitivity of PET/CT and MDCT was 97.3% and 70.3% (p = 0.002); the specificity of both techniques was 94.4% (p = 1.0). In a tumor site-based analysis, the sensitivities of PET/CT and MDCT were 98.1% and 66.7% (p < 0.0001), and the specificities were 75% and 62.5% (p = 0.56). Tumors correctly identified with PET/CT and missed with MDCT were local recurrence in the presacral space (n = 5), metastatic subcentimeter lymph nodes (n = 4), peritoneal deposits (n = 3), and recurrences at the periphery of radiofrequency ablated metastatic lesions of the liver (n = 2) and in the abdominal wall (n = 1), liver (n = 1), and uterine cervix (n = 1).

CONCLUSION

FDG PET/CT has higher sensitivity than MDCT in the identification of sites of recurrent and metastatic disease in patients with colorectal cancer and an elevated CEA level. The two techniques appear to have similar specificity.

Imaging as a surveillance tool in rectal cancer

Despite advances in diagnosis and treatment, half of patients with treated rectal cancer will die owing to recurrent disease. There is no evidence of benefit on survival from an intensive surveillance program, even if presymptomatic recurrent disease is detected. The aim of this article is to review the results described for the different imaging techniques in diagnosing rectal cancer recurrence in different sites and to discuss their relative clinical impact. The sensitivity of imaging techniques is related to the performance of the machines and the site being examined. Computed tomography is the most used technique owing to its availability, speed, panoramic images and ease of use, while MRI of the pelvis and the liver produces the highest resolution, sensitivity and specificity in these anatomical areas. Owing to its high cost, [(18)F] fluorodeoxyglucose-PET should be used as a third-level examination, a 'problem-solving' method when the site of recurrence is unknown or to rule out other possible sites of recurrence before a second surgery, and, finally, because it offers the possibility to investigate the whole body. The follow-up must be designed for individual patients, taking into account a number of factors. In the near future, whole-body imaging, probably by MRI, that is free from radiation will become the method of choice for screening for recurrent disease.

Comparison of magnetic resonance imaging–fluorodeoxy- glucose positron emission tomography fusion with pathological staging in rectal cancer

Background

This study represents an initial experience with combined magnetic resonance imaging (MRI) and [18F]fluorodeoxyglucose positron emission tomography (FDG PET) (MRI–PET fusion) in the primary staging of rectal carcinoma.

Methods

A retrospective analysis of data recorded on patients with rectal cancer was undertaken. Patients requiring long-course radiotherapy were excluded. Chest radiography, abdominal computed tomography and endorectal ultrasonography were performed. In addition, MRI of the pelvis, whole-body FDG PET and MRI–PET fusion were carried out. All patients subsequently underwent anterior resection.

Results

Twenty-three patients with rectal carcinoma (15 men), of median age 60 (range 46–75) years, were enrolled. In tumour (T) assessment, MRI correctly staged 14 of 22 T2/T3 tumours. In lymph node assessment, MRI–PET fusion had a sensitivity of 44 per cent, with a specificity and positive predictive value of 100 per cent. No additional information was acquired from MRI–PET fusion over MRI plus abdominal computed tomography and chest radiography.

Conclusion

MRI–PET fusion adds little to conventional investigations for staging rectal carcinoma.