Clinical value of whole-body positron emission tomography with [18F]fluorodeoxyglucose in recurrent colorectal cancer

The Influence of Blood Glucose Levels on [18F]Fluorodeoxyglucose (Fdg) Uptake in Cancer: A Pet Study in Liver Metastases from Colorectal Carcinomas

Aims and background

To study the influence of blood glucose levels on the clinical reliability of positron emission tomography (PET) with [18F]-2-fluoro-2-deoxy-D-glucose (FDG) in the detection of liver metastases from colorectal carcinomas and in the analysis of tumor uptake of FDG.

Methods

After having given their informed consent, 8 patients with 20 liver metastases (mean size, 31.5 mm; range, 10–75 mm) detected by means of CT were submitted to a first FDG-PET examination under fasting conditions and, 2 days later, to a second FDG-PET examination performed after iv infusion of a glucose solution (4 mg/kg/min for 2 hrs). The results of the two studies were compared in each patient, considering both the localization of the metastases and the FDG uptake in the lesions. A non-kinetic method was used, calculating the Standardized Uptake Value (SUV).

Results

All 20 metastases were clearly visible on FDG-PET under fasting conditions. Moreover, in 2 patients FDG-PET detected a number of unknown liver metastases. The blood glucose levels after glucose infusion were significantly higher than the levels under fasting conditions, 158 ± 13.8 mg/100 ml (mean ± sd) and 92.4 ± 10.2, respectively (P « 0.001), and the quality of the FDG-PET images showed a marked deterioration. FDG-PET was unable to detect 6 of the 20 lesions and another 10 lesions were localized less clearly. Moreover, 80% of the unknown liver metastases were not detected after glucose loading. The SUVs of metastases decreased from 9.4 ± 5.7 (mean ± sd) under fasting conditions to 4.3 ± 8.3 after glucose loading (P « 0.001).

Conclusions

FDG-PET studies may be particularly unreliable under conditions of high levels of blood glucose. Therefore, patients entering FDG-PET studies should fast, and blood glucose concentration needs to be taken into account when evaluating FDG uptakes in follow-up studies.

Blood CEA levels for detecting recurrent colorectal cancer

BACKGROUND

Testing for carcino-embryonic antigen (CEA) in the blood is a recommended part of follow-up to detect recurrence of colorectal cancer following primary curative treatment. There is substantial clinical variation in the cut-off level applied to trigger further investigation.

OBJECTIVES

To determine the diagnostic performance of different blood CEA levels in identifying people with colorectal cancer recurrence in order to inform clinical practice.

SEARCH METHODS

We conducted all searches to January 29 2014. We applied no language limits to the searches, and translated non-English manuscripts. We searched for relevant reviews in the MEDLINE, EMBASE, MEDION and DARE databases. We searched for primary studies (including conference abstracts) in the Cochrane Central Register of Controlled Trials (CENTRAL), in MEDLINE, EMBASE, and the Science Citation Index & Conference Proceedings Citation Index - Science. We identified ongoing studies by searching WHO ICTRP and the ASCO meeting library.

SELECTION CRITERIA

We included cross-sectional diagnostic test accuracy studies, cohort studies, and randomised controlled trials (RCTs) of post-resection colorectal cancer follow-up that compared CEA to a reference standard. We included studies only if we could extract 2 x 2 accuracy data. We excluded case-control studies, as the ratio of cases to controls is determined by the study design, making the data unsuitable for assessing test accuracy.

DATA COLLECTION AND ANALYSIS

Two review authors (BDN, IP) assessed the quality of all articles independently, discussing any disagreements. Where we could not reach consensus, a third author (BS) acted as moderator. We assessed methodological quality against QUADAS-2 criteria. We extracted binary diagnostic accuracy data from all included studies as 2 x 2 tables. We conducted a bivariate meta-analysis. We used the xtmelogit command in Stata to produce the pooled estimates of sensitivity and specificity and we also produced hierarchical summary ROC plots.

MAIN RESULTS

In the 52 included studies, sensitivity ranged from 41% to 97% and specificity from 52% to 100%. In the seven studies reporting the impact of applying a threshold of 2.5 µg/L, pooled sensitivity was 82% (95% confidence interval (CI) 78% to 86%) and pooled specificity 80% (95% CI 59% to 92%). In the 23 studies reporting the impact of applying a threshold of 5 µg/L, pooled sensitivity was 71% (95% CI 64% to 76%) and pooled specificity 88% (95% CI 84% to 92%). In the seven studies reporting the impact of applying a threshold of 10 µg/L, pooled sensitivity was 68% (95% CI 53% to 79%) and pooled specificity 97% (95% CI 90% to 99%).

AUTHORS' CONCLUSIONS

CEA is insufficiently sensitive to be used alone, even with a low threshold. It is therefore essential to augment CEA monitoring with another diagnostic modality in order to avoid missed cases. Trying to improve sensitivity by adopting a low threshold is a poor strategy because of the high numbers of false alarms generated. We therefore recommend monitoring for colorectal cancer recurrence with more than one diagnostic modality but applying the highest CEA cut-off assessed (10 µg/L).

Repeated resection of colorectal cancer pulmonary oligometastases: pooled analysis and prognostic assessment

BACKGROUND

Repeated resection of colorectal cancer pulmonary metastasis is associated with long-term survival. Nevertheless, very limited data addressing the best candidates for repeated pulmonary resection is available.

PATIENTS AND METHODS

We searched the PubMed database for retrospective studies evaluating lung metastasectomy for metastatic colorectal cancer (CRC). We included studies with available data about repeated pulmonary metastasectomy. Potential prognostic factors were analyzed for possible impact on survival following the second metastasectomy through univariate and multivariate analysis.

RESULTS

Between 1983 and 2008, 944 lung metastasectomies were carried out on 759 patients. Of those, 148 patients had a second metastasectomy. The 5-year survival rate was 52 % for patients who had 1 metastasectomy and 57.9 % from the second metastasectomy for patients who had repeated resection. More than 2 metastatic pulmonary nodules and maximum diameter of largest pulmonary nodule ≥3 cm were the only independent factors associated with inferior survival following repeated pulmonary resection.

CONCLUSIONS

In selected patients with metastatic CRC, repeated pulmonary metastasectomy offers an excellent chance for long-term survival and is associated with a quite low operative mortality. Patients with more than 2 metastatic nodules and a maximum diameter of the largest metastatic lung nodule of ≥3 cm have a significantly inferior survival.

Surgical management of colorectal lung metastasis

Colon cancer is a systemic disease in 19% of patients and metastasizes most frequently to the liver and the lung. Survival is enhanced with complete surgical resection of pulmonary metastases. Comprehensive restaging and verification of preoperative fitness must precede resection. The operative approach is dictated by the anatomic location of the metastases, whereas the extent of resection remains a balance between complete removal of metastatic deposits while preserving as much lung parenchyma as possible. The presence of metastatic involvement of hilar and mediastinal lymph nodes is ominous. Multidisciplinary care is highly recommended. An evidence-based algorithm for the identification assessment and treatment of patients with pulmonary metastases is proposed.

Positron emission tomography and colorectal cancer

Colorectal cancer (CRC) is a major cause of cancer-related morbidity and mortality. Molecular imaging using positron emission tomography (PET) is now an integral part of multidisciplinary cancer care. In this review, we discuss the role of PET in CRC including well established indications in the assessment of recurrent disease and emerging applications such as initial staging, monitoring therapy efficacy and using PET for radiotherapy planning. With rapid advancement in imaging technology, we also discuss the future potential of combining PET and magnetic resonance imaging and the use of novel radiotracers.

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.

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 preoperative whole-body positron emission tomography with MDCT in patients with primary colorectal cancer

OBJECTIVE

Preoperative use of emission tomography with(18)F-fluorodeoxyglucose (FDG-PET) in patients with primary colorectal cancer remains controversial. This study evaluated the additional value of FDG-PET in comparison with routine multidetector row computed tomography (MDCT) in patients with primary colorectal cancer.

METHOD

Retrospective analysis was performed in 65 patients with colorectal cancer who underwent whole-body FDG-PET. Results of FDG-PET were compared with routine preoperative evaluation by MDCT regarding detection of primary tumour, lymph node involvement and distant metastases. All images were evaluated before surgery.

RESULTS

Tumour detection rate was 100% (63/63) for MDCT and 98% (62/63) for FDG-PET. Lymph node involvement was pathologically confirmed in 35 patients. MDCT and FDG-PET displayed sensitivities of 89% (31/35; 95% CI: 73-97%) and 43% (15/35; 95% CI: 26-61%) and specificities of 52% (11/21; 95% CI: 30-74%) and 95% (20/21; 95% CI: 76-100%), respectively. Liver metastases were present in 22 patients. MDCT and FDG-PET showed accuracies of 98% (64/65; 95% CI: 92-100%) and 97% (63/65; 95% CI: 89-100%), respectively. FDG-PET detected additional extrahepatic metastatic lesions and affected treatment plan compared with MDCT in 10 patients.

CONCLUSION

Preoperative FDG-PET is not superior to MDCT for detection of primary tumour, lymph node involvement or liver metastases, but may have potential clinical value in patients with advanced colorectal cancer by detecting extrahepatic distant metastases.

Diagnostic value of FDG-PET in recurrent colorectal carcinoma: a meta-analysis

Accurate detection of recurrent colorectal carcinoma remains a diagnostic challenge. The purposes of this study were to evaluate the diagnostic value of Positron emission tomography (PET) using fluor-18-deoxyglucose (FDG) in recurrent colorectal carcinoma with a meta-analysis. All the published studies in English relating the diagnostic value of FDG-PET in the detection of recurrent colorectal carcinoma were collected. Methodological quality of the included studies was evaluated. Pooled sensitivity, specificity and diagnostic odds ratio and SROC (summary receiver operating characteristic curves) were obtained by the statistical software. Twenty-seven studies were included in the meta-analysis. The pooled sensitivity and specificity for FDG-PET detecting distant metastasis or whole body involvement in recurrent colorectal carcinoma were 0.91 (95% CI 0.88-0.92) and 0.83 (95% CI 0.79-0.87), respectively. The pooled sensitivity and specificity for FDG-PET detecting hepatic metastasis were 0.97 (95% CI 0.95-0.98) and 0.98 (95% CI 0.97-0.99). The pooled sensitivity and specificity for pelvic metastasis or local regional recurrence were 0.94 (95% CI 0.91-0.97) and 0.94 (95% CI 0.92-0.96). FDG-PET is valuable for the assessment of recurrent colorectal carcinoma.

Management of recurrent colorectal cancer with positron emission tomography

The use of positron emission tomography, on its own and in combination with computed tomography, has been integrated into the management algorithm of patients with suspected recurrence of colorectal cancer. This article looks at the biological basis of positron emission tomography, its clinical advantages and disadvantages.

Positron Emission Tomography Detection of Distant Metastatic or Synchronous Disease in Patients with Locally Advanced Rectal Cancer Receiving Preoperative Chemoradiation

BACKGROUND

Patients with locally advanced rectal cancer may present with synchronous distant metastases. Choice of optimal treatment--neoadjuvant chemoradiation versus systemic chemotherapy alone--depends on accurate assessment of distant disease. We prospectively evaluated the ability of [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomography (PET) to detect distant disease in patients with locally advanced rectal cancer who were otherwise eligible for combined modality therapy (CMT).

METHODS

Ninety-three patients with locally advanced rectal cancer underwent whole-body [18F]FDG PET scanning 2-3 weeks before starting CMT. Sites other than the rectum, mesorectum, or the area along the inferior mesenteric artery were considered distant and were divided into nine groups: neck, lung, mediastinal lymph node (LN), abdomen, liver, colon, pelvis, peripheral LN, and soft tissue. Two nuclear medicine physicians blinded to clinical information used PET images and a five-point scale (0-4) to determine certainty of disease. A score greater than 3 was considered malignant. Confirmation was based on tissue diagnosis, surgical exploration, and subsequent imaging.

RESULTS

At a median follow-up of 34 months, the overall accuracy, sensitivity, and specificity of PET in detecting distant disease were 93.7%, 77.8%, and 98.7% respectively. Greatest accuracy was demonstrated in detection of liver (accuracy = 99.9%, sensitivity = 100%, specificity = 98.8%) and lung (accuracy = 99.9%, sensitivity = 80%, specificity = 100%) disease; PET detected 11/12 confirmed malignant sites in liver and lung. A total of 10 patients were confirmed to have M1 stage disease. All 10 were correctly staged by pre-CMT PET; abdominopelvic computed tomography (CT) scans accurately detected nine of them.

CONCLUSION

Baseline PET in patients with locally advanced rectal cancer reliably detects metastatic disease in liver and lung. PET may play a significant role in defining extent of distant disease in selected cases, thus impacting the choice of neoadjuvant therapy.

The role of FDG-PET in the selection of patients with colorectal liver metastases

BACKGROUND

Selection of patients for hepatic resection of colorectal liver metastases is still limited. After conventional work up by computed tomography (CT) scan, 60% of patients will develop recurrent disease in the early years after resection. The aim of the present study was to evaluate whether an additional fluorine-18-deoxyglucose positron emission tomography (FDG-PET) improves patient selection and therefore adds value to select patients for curative liver resection.

METHODS

Data from 203 patients selected for surgical treatment of colorectal liver metastases between 1995 and 2003 were collected in a prospective database. Group A consisted of 100 consecutive patients selected for hepatic surgery by conventional diagnostic imaging (CT chest and abdomen) only. Group B consisted of 103 consecutive patients selected for hepatic surgery by conventional diagnostic methods plus an additional FDG-PET.

RESULTS

The number of patients with futile surgery, in which further treatment was considered inappropriate at laparotomy, was 28.0% in group A and 19.4% in group B. The reason for unresectable disease differed between groups. In group A, 10/100 (10.0%) patients showed extrahepatic abdominal disease versus 2/103 patients (1.9%) in group B (P = .017). In all other cases, resection was not performed because liver disease proved too extensive at laparotomy. For patients ultimately undergoing surgical treatment of the metastases, survival was comparable between groups. Overall survival at 3 years was 57.1% in group A versus 60.1% in group B. Disease-free survival at 3 years was 23.0% in group A and 31.4% in group B.

CONCLUSIONS

In patients with colorectal liver metastases, FDG-PET may reduce the number of negative laparotomies. However, the effect size on the selection of these patients seems not sufficient enough to affect the overall and disease-free survival after treatment.

The role of positron emission tomography in the management of recurrent colorectal cancer: a review

PURPOSE

Surgery remains the only option for potential cure in patients with recurrent colorectal cancer. Accurate staging modalities aid in the avoidance of futile surgery, which may result in considerable morbidity in patients with incurable disease. Current imaging techniques used in disease staging often are not sensitive enough to identify low-volume metastatic disease. This study reviews the role of positron emission tomography in the assessment of patients with suspected recurrent colorectal cancer.

METHODS

A literature search using the PubMed, MEDLINE, and Embase database was performed, locating English language articles on positron emission tomography, positron emission tomography, recurrent colon, and/or rectal cancer. The references of these papers were searched manually for further references.

RESULTS

Positron emission tomography is more sensitive and more specific than conventional diagnostic imaging for metastatic disease and local recurrence respectively. Studies confirm the superior ability of positron emission tomography scans compared with conventional diagnostic imaging in differentiating between scar tissue and invasive tumor. Positron emission tomography scanning is more sensitive and specific for the assessment of liver metastases (and probably in patients with lung metastasis) than conventional diagnostic imaging. Positron emission tomography is superior to conventional diagnostic imaging in the investigation of raised carcinoembryonic antigen in the postoperative patient and alters management in approximately 37 percent of patients with recurrent colorectal cancer. The limitations and cost effectiveness of positron emission tomography are discussed.

CONCLUSIONS

Positron emission tomography scanning is emerging as the imaging modality of choice for patients being considered for surgery for locally recurrent colorectal cancer. Positron emission tomography has the greatest impact by detecting unresectable disease and thereby averting inappropriate surgery. Despite the high set-up costs, its use seems to be cost effective.

The role of 18F-fluoro-deoxy-glucose positron emission tomography (FDG-PET) in the management of patients with colorectal cancer

AIM

In patients with colorectal cancer an accurate diagnostic work-up is mandatory in order to perform the most specific treatment. At this moment 18F-fluoro-deoxy-glucose positron emission tomography (FDG-PET) is considered an accurate imaging technique in staging/restaging several malignancies. The aim of this paper is to review the scientific literature available about the role of FDG-PET in the management of patients with colorectal cancer.

METHODS

An overview on Medline of scientific literature concerning FDG-PET and colorectal cancer was performed. The most relevant studies are reported. Advantages, limitations and new chances in using FDG-PET in these subsets of patients are summarized.

RESULTS

FDG-PET is a useful tool in the evaluation of colorectal cancer. In comparison to conventional imaging technique, FDG-PET has an additional diagnostic value because it allows to metabolically characterize undetermined lesions suspected for recurrence of disease, to perform a complete pre-surgical staging and to identify occult metastatic disease. In clinical practice its use leads to a change in therapeutic choices in a high percentage of cases.

CONCLUSIONS

FDG-PET should be considered an essential diagnostic tool in the management of patients with colorectal cancer, especially in recurrent disease evaluation.

Surgery for local recurrence of rectal cancer

OBJECTIVE

Despite improvement in management of primary rectal cancer, 2.6-32% of patients develop local recurrence. A proportion of these patients can be amenable to salvage surgery. The present article reviews the evidence for and against the surgical management for local recurrence of rectal cancer, the role of adjuvant and intraoperative radiotherapy (IORT), and evaluates short and long-term outcomes.

METHOD

A literature search was performed using Medline, Embase, Ovid and Cochrane database for studies between 1980 and 2005 assessing surgical management of local recurrence of rectal cancer and the evidence was critically evaluated.

RESULTS

Nearly 50% of rectal cancer recurrences are local and are therefore potentially amenable to curative resection. Preoperative imaging is important for appropriate selection of patients for surgery and preoperative adjuvant therapy is essential. Five-year survival following resection ranges from 18% to 58% with 5-year survival following complete resection of over 35% though morbidity ranges from 21% to 82%. Neoadjuvant radiotherapy is beneficial and IORT may have a contributory role in treatment. Aggressive surgical treatment favourably affects quality of life and is cost effective. Surgery for local recurrence can result in significant long-term survival with acceptable morbidity and improved quality of life in appropriately selected patients. Assessment in a specialist centre familiar with these techniques is essential.

FDG-PET in colorectal cancer

[18F]Fluorodeoxyglucose (FDG) positron emission tomography (PET) is a useful imaging tool in the evolving management of patients with colorectal carcinoma. This technique is able to measure and visualize metabolic changes in cancer cells. This feature results in the ability to distinguish viable tumor from scar tissue, in the detection of tumor foci at an earlier stage than possible by conventional anatomic imaging and in the measurement of alterations in tumor metabolism, indicative of tumor response to therapy. Nowadays, FDG-PET plays a pivotal role in staging patients before surgical resection of recurrence and metastases, in the localization of recurrence in patients with an unexplained rise in serum carcinoembryonic antigen and in assessment of residual masses after treatment. In the presurgical evaluation, FDG-PET may be best used in conjunction with anatomic imaging in order to combine the benefits of both anatomical (CT) and functional (PET) information, which leads to significant improvements in preoperative liver staging and preoperative judgment on the feasibility of resection. Integration of FDG-PET into the management algorithm of these categories of patients alters and improves therapeutic management, reduces morbidity due to futile surgery, leads to substantial cost savings and probably also to a better patient outcome. FDG-PET also appears to have great potential in monitoring the success of local ablative therapies soon after intervention and in the prediction and evaluation of response to radiotherapy, systemic therapy, and combinations thereof. This review aims to outline the current and future role of FDG-PET in the field of colorectal cancer.

Is 3′-deoxy-3′-18F-fluorothymidine a better marker for tumour response than 18F-fluorodeoxyglucose?

3'-Deoxy-3'-(18)F-fluorothymidine (FLT) was developed in 1998 by Shields and co-workers because monitoring of treatment response would be facilitated by imaging agents able to provide measures of tissue and tumour proliferation. Since then, FLT metabolism has been clarified in more detail in cell culture and experimental animal tumour models and also in clinical studies. Recently, FLT has increasingly been used for the assessment of response to anticancer treatment, mainly in tumour xenograft SCID mouse models; in contrast, clinical data are scarce. In this article we briefly summarise the intermediary metabolism of FLT and its application as an anticancer treatment response probe. The potential value and limitations of FLT as a highly promising proliferation imaging probe and its use for monitoring of treatment response are discussed.

Surgical treatment of liver metastases of colorectal cancer: Strategies and controversies in 2006

AIMS

To review the latest strategies and controversies in the surgical treatment of liver metastases of colorectal cancer systemically and comprehensively.

METHODS

A medline based literature search on relevant topics was performed in PubMed for key articles concerning the novel strategies and controversies in the management of liver metastases of colorectal cancer. Some information was obtained from 'Proc Am Soc Clin Oncol' published recently. The findings and discussions were related to our own experiences.

RESULTS

Although for well-indicated patients, a consensus has been reached that hepatic resection is the only management that could provide the patients curability, there still exist many controversies, such as the prognostic evaluation, contraindications to hepatic resection, treatment for synchronous liver metastases, the place of laparoscopic surgery, etc. Meanwhile, various strategies to improve the respectabilities are available, including neoadjuvant chemotherapy, portal vein embolization, two stage hepatectomy, and some locally ablative approaches. The current condition is difficult and sometimes confusing for a relevant surgeon when designing treatment protocols for more complex diseases.

CONCLUSION

As the advancing of the management of liver metastases of colorectal cancer, more patients will become candidates for and benefit from potentially curative surgical resections. Optimal effect could only be achieved when used in a manner tailored to the individual patient.

The impact of fluor-18-deoxyglucose-positron emission tomography in the management of colorectal liver metastases

Fluor-18-deoxyglucose-positron emission tomography (FDG-PET) has emerged as a promising diagnostic modality in recurrent colorectal carcinoma. Whole-body FDG-PET may be an accurate diagnostic modality to determine whether patients with recurrent hepatic disease are suitable candidates for curative resection. Reports on the use of FDG-PET in patients with recurrent colorectal carcinoma are scarce, especially those on colorectal liver metastases. To assess the usefulness of this emerging modality for the selection of patients to undergo resection for colorectal liver metastases, a systematic (meta)-analysis of the current literature was conducted. In the absence of randomized controlled clinical trials, a traditional meta-analysis could not be performed. An alternative strategy was designed to evaluate the current literature. After a literature search, an index score was devised to evaluate the articles with regard to the impact of FDG-PET in patients with colorectal liver metastases. The index scored articles on several items and, as such, could be considered an objective approach for the assessment of diagnostic, nonrandomized clinical trials. The proposed index proved to be an independent instrument for judging several research questions and was used systematically to address the sensitivity, specificity, and clinical impact of FDG-PET in patients with colorectal liver metastases. For FDG-PET, the pooled sensitivity and specificity results were 88.0% and 96.1%, respectively, for hepatic disease and 91.5% and 95.4%, respectively, for extrahepatic disease. For the 6 articles that reported the highest scores on the index, the sensitivity and specificity of FDG-PET for hepatic metastatic disease were 79.9% and 92.3%, respectively, and 91.2% and 98.4%, respectively, for extrahepatic disease, respectively. For computed tomography, the pooled sensitivity and specificity results were 82.7% and 84.1%, respectively, for hepatic lesions and 60.9% and 91.1%, respectively, for extrahepatic lesions. The percentage change in clinical management due to FDG-PET was 31.6% (range, 20.0-58.0%) in the articles that scored above the mean and reported this item. For the 6 highest scoring studies, the percentage change in clinical management was 25.0% (range, 20.0-32.0%). Despite apparent omissions in the literature, the combined sensitivity and specificity of FDG-PET clearly indicated that FDG-PET has added value in the diagnostic workup of patients with colorectal liver metastases. FDG-PET can be considered a useful tool in preoperative staging and produced superior results compared with conventional diagnostic modalities, especially for excluding or detecting extrahepatic disease.

The Economic Impact of 18FDG Positron Emission Tomography in the Surgical Management of Colorectal Cancer with Hepatic Metastases

BACKGROUND

(18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) is recognized as a powerful tool in the management of patients with recurrent and/or metastatic colorectal cancer. The aim of this was was to analyze costs from the payer's perspective, of adding FDG-PET to a computed tomography (CT) scan preoperatively in colorectal cancer patients with resectable hepatic metastases.

METHODS

CT with and without FDG-PET were compared among patients with colorectal cancer in staging for surgical resection of hepatic metastases. Outcomes included uncomplicated surgery, complicated surgery, or death. Extrahepatic disease occurrence rates and diagnostic accuracy of CT and FDG-PET were obtained from published sources. Complication rates and costs for CT, FDG-PET, and surgical procedures were obtained from Healthcare Finance Administration data.

RESULTS

The average expected surgical cost per patient when FDG-PET was used to determine the presence of extrahepatic disease was 16,278 dollars compared to 21,547 dollars for conventional management-a net savings of 5,269 dollars.

CONCLUSIONS

Integration of FDG-PET into the presurgical evaluation of patients with hepatic metastases could substantially reduce overall costs and patients' morbidity. This substantial net saving results from the unique ability of FDG-PET in excluding patients with extrahepatic disease, and avoiding unnecessary surgical expenses.

Surgical therapy for metastatic disease to the liver

The liver is a common site of hematogenous metastasis. In the past, patients with liver metastases were often deemed inoperable, and medical therapy conferred only minor survival benefit. However, advances in surgical techniques and chemotherapeutic agents during the past two decades have led to effective treatments for selected patients with metastases to the liver. Up to approximately 80% of the liver can be resected, and partial hepatectomy is now routinely performed with a perioperative mortality rate of <5%. Surgical resection of colorectal cancer metastatic to the liver results in a 5-year survival rate of 40%. These results are expected to improve even further with multimodality approaches that include newer chemotherapy regimens. Liver metastases from other primary tumors, such as neuroendocrine carcinoma and genitourinary tumors, are also treated effectively with liver resection. The indications for surgical treatment of liver metastases are broadening as a variety of novel therapies are being developed, including hepatic artery embolization, hepatic artery infusion of chemotherapy, and radiofrequency ablation.

Correlation between serum CEA level and metabolic volume as determined by FDG PET in postoperative patients with recurrent colorectal cancer

To determine the correlation between serum CEA level and the metabolic volume by FDG PET in postoperative patients with recurrent colorectal cancer, FDG PET was performed in 29 consecutive patients with recurrent or metastatic colorectal cancer whose CEA levels were higher than 5 ng/ml. A whole body emission scan was performed 60 minutes after injecting 370-555 MBq of F-18 FDG. "PET volume" and "PET metabolic volume" of tumors were measured on FDG PET images. Based on an isocontour plot of tumor mass at 2.5 SUV (standardized uptake value), the metabolically active tumor "PET volume" was calculated. "PET metabolic volume" was obtained by multiplying the "PET volume" by the mean SUV of the tumor. All recurrent or metastatic lesions were single or multiple lesions of measurable size (axial diameter > 1 cm, minimum "PET volume" 3.5 cm3), and were verified by operation or by other imaging modalities (CT or MRI). There was a linear associations between "PET volume" and serum CEA level. Further regression analysis by least squares showed a highly significant model with an equation of volume = 41.2 + 0.471 x CEA (r2 = 0.629). However, no such association was found between "PET metabolic volume" and serum CEA level according to the residual normality test. In conclusion, "PET volume" measured by FDG PET and serum CEA level in colorectal cancer are significantly correlated. Tumor volume determined by FDG PET can be used as an effective marker of tumor burden in postoperative patients with colorectal carcinoma.

The Utility of 2-Deoxy-2-[F-18]fluoro-d-glucose Positron Emission Tomography in the Investigation of Patients with Disseminated Carcinoma of Unknown Primary Origin

PURPOSE

A retrospective analysis of the use of 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) positron emission tomography (PET) was performed in patients with histologically proven disseminated carcinoma of unknown primary tumor (CUP).

PROCEDURES

The records of 31 patients with CUP, excluding patients with isolated neck metastases, were reviewed to identify the ability of PET to detect the putative primary site (PPS) and/or to change therapeutic management.

RESULTS

In eight out of 31 cases (26%), a PPS was confirmed, either definitively (one pathologically, one radiologically) (true positive) or clinically (six cases). For three cases (10%), histological evidence of a primary tumor distant from the PPS was found (false positive). In a further seven cases (23%), the PPS remained unconfirmed, whereas for 13 cases (42%) no PPS was identified. In five out of seven patients in whom the PET suggested a high probability of having identified the primary site, the PPS was confirmed definitively or clinically. PET altered clinical management in at least 12 cases (38%).

CONCLUSIONS

PET contributed to the management of previously extensively investigated patients with CUP. Identification of a PPS and/or change in management was documented in 38% of cases, the majority of which were lung or pancreatic cancer. These findings are worthy of evaluation in a prospective study.

Does the novel PET/CT imaging modality impact on the treatment of patients with metastatic colorectal cancer of the liver?

OBJECTIVE

To compare the diagnostic value of contrast-enhanced CT (ceCT) and 2-[18-F]-fluoro-2-deoxyglucose-PET/CT in patients with metastatic colorectal cancer to the liver.

BACKGROUND

Despite preoperative evaluation with ceCT, the tumor load in patients with metastatic colorectal cancer to the liver is often underestimated. Positron emission tomography (PET) has been used in combination with the ceCT to improve identification of intra- and extrahepatic tumors in these patients. We compared ceCT and a novel fused PET/CT technique in patients evaluated for liver resection for metastatic colorectal cancer.

METHODS

Patients evaluated for resection of liver metastases from colorectal cancer were entered into a prospective database. Each patient received a ceCT and a PET/CT, and both examinations were evaluated independently by a radiologist/nuclear medicine physician without the knowledge of the results of other diagnostic techniques. The sensitivity and the specificity of both tests regarding the detection of intrahepatic tumor load, extra/hepatic metastases, and local recurrence at the colorectal site were determined. The main end point of the study was to assess the impact of the PET/CT findings on the therapeutic strategy.

RESULTS

Seventy-six patients with a median age of 63 years were included in the study. ceCT and PET/CT provided comparable findings for the detection of intrahepatic metastases with a sensitivity of 95% and 91%, respectively. However, PET/CT was superior in establishing the diagnosis of intrahepatic recurrences in patients with prior hepatectomy (specificity 50% vs. 100%, P = 0.04). Local recurrences at the primary colo-rectal resection site were detected by ceCT and PET/CT with a sensitivity of 53% and 93%, respectively (P = 0.03). Extrahepatic disease was missed in the ceCT in one third of the cases (sensitivity 64%), whereas PET/CT failed to detect extrahepatic lesions in only 11% of the cases (sensitivity 89%) (P = 0.02). New findings in the PET/CT resulted in a change in the therapeutic strategy in 21% of the patients.

CONCLUSION

PET/CT and ceCT provide similar information regarding hepatic metastases of colorectal cancer, whereas PET/CT is superior to ceCT for the detection of recurrent intrahepatic tumors after hepatectomy, extrahepatic metastases, and local recurrence at the site of the initial colorectal surgery. We now routinely perform PET/CT on all patients being evaluated for liver resection for metastatic colorectal cancer.

Role of FDG-PET in surgical management of patients with colorectal liver metastases

BACKGROUND

[(18)F]-fluorodeoxyglucose positron emission tomography (FDG-PET) is reported to change the management in 20-56% of patients with recurrent or metastatic colorectal cancer. It is not clear if FDG-PET has a role in all such patients or only a subgroup. The aim of the present study was to assess the influence of FDG-PET on the surgical management of patients with known or suspected colorectal liver metastases.

METHODS

Patients undergoing FDG-PET for investigation of known or suspected colorectal liver metastases were identified from a South Australian database. Case notes were reviewed retrospectively to determine the influence of FDG-PET findings on patient management. Findings from FDG-PET scanning were compared with findings from conventional diagnostic investigations and operative findings.

RESULTS

Overall, in four of 16 patients (25%) management was influenced by FDG-PET findings. FDG-PET altered management in four of eight (50%) patients with non-diagnostic liver lesions on computed tomography (CT) or with elevated carcinoembryonic antigen levels but no liver lesion on CT. In all eight patients with CT diagnosed resectable liver metastases, the addition of FDG-PET did not influence the management.

CONCLUSIONS

The findings support the use of FDG-PET in the assessment of selected patients with suspected colorectal liver metastases and equivocal findings on conventional diagnostic investigation.

[PET/CT for colorectal and hepatic tumors]

This contribution presents clinical and technical aspects of combining positron emission tomography (PET) and computed tomography (CT) for patients with colorectal tumors and characterization of unclear liver foci. In which manner and for which patients combined PET/CT is superior to PET or CT alone is also discussed. PET/CT can fulfil most prerequisites for imaging in pre- and postoperative management of patients with colorectal tumors and best meets the desire for optimal imaging procedures. Some of the disadvantages encountered in frequently employed CT can be overcome by the combination of PET and CT while increasing both sensitivity in detecting lesions and specificity in their characterization. Questions regarding treatment response offer an opportunity for devising novel study concepts and initiating research on new PET tracers. Although few publications are available, we are of the opinion that the combination of functional and anatomical imaging provided by PET/CT can improve both preoperative management and aftercare. To this end, however, optimum cooperation between practitioners of nuclear medicine and radiology is imperative.

PET imaging in assessing gastrointestinal tumors

The clinical usefulness of FDG-PET imaging is now firmly established in various situations, such as the preoperative staging of esophageal cancer and recurrent colorectal carcinoma and the detection and staging of recurrent colorectal cancer when there is a clinical or biologic suspicion with inconclusive conventional findings. Encouraging results were obtained in the evaluation of the therapeutic response of various gastrointestinal malignancies, either during the treatment or after its completion. There is no firm consensus regarding its role in pancreatic cancer, either proved or suspected, but it may be valuable in selected clinical situations. Its role seems fairly limited in patients with hepatocellular carcinoma, although PET findings may have prognostic implications. Evaluation of cholangiocarcinoma is an emerging indication, albeit with limited data to date. Finally, PET/CT is very likely to enhance the role of FDG imaging further in the work-up of patients with gastrointestinal tumors.

PET and PET-CT for evaluation of colorectal carcinoma

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. FDG-PET does not replace imaging modalities such as computed tomography (CT) for preoperative anatomic evaluation but 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 to the evaluation of these patients reduces overall treatment costs by accurately identifying patients who will and will not benefit from surgical procedures. Although initial staging at the time of diagnosis is often performed during colectomy, FDG-PET imaging is recommended for a subgroup of patients at high risk (with elevated CEA levels) and normal CT and for whom surgery can be avoided if FDG-PET shows metastases. Screening for recurrence in patients at high risk has also been advocated. FDG-PET imaging seems promising for monitoring patient response to therapy but larger studies are necessary. The diagnostic implications of integrated PET-CT imaging include improved detection of lesions on both the CT and FDG-PET images, better differentiation of physiologic from pathologic foci of metabolism, and better localization of the pathologic foci. 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, radiation therapy), excluding the need for additional procedures, and changing both inter- and intramodality therapy.

Five-year survival after resection of hepatic metastases from colorectal cancer in patients screened by positron emission tomography with F-18 fluorodeoxyglucose (FDG-PET)

OBJECTIVE

To report the first 5-year overall survival results in patients with colorectal carcinoma metastatic to the liver who have undergone hepatic resection after staging with [18F] fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET).

SUMMARY BACKGROUND DATA

The 5-year overall survival after hepatic resection for colorectal cancer metastases without preoperative FDG-PET has been established in 19 studies (6070 patients). The median 5-year overall survival rate in these studies is 30% and has not improved over time. FDG-PET detects unsuspected tumor in 25% of patients considered to have resectable hepatic metastasis by conventional staging.

METHODS

From March 1995 to June 2002, all patients having hepatic resection for colorectal cancer metastases had preoperative FDG-PET. A prospective database was maintained.

RESULTS

One hundred patients (56 men, 44 women) were studied. Metastases were synchronous in 52, single in 63, unilateral in 78, and <5 cm in diameter in 60. Resections were major (>3 segments) in 75 and resection margins were > or = 1 cm in 52. Median follow up was 31 months, with 12 actual greater than 5-year survivors. There was 1 postoperative death. The actuarial 5-year overall survival was 58% (95% confidence interval, 46-72%). Primary tumor grade was the only prognostic variable significantly correlated with overall survival.

CONCLUSIONS

Screening by FDG-PET is associated with excellent postresection 5-year overall survival for patients undergoing resection of hepatic metastases from colorectal cancer. FDG-PET appears to define a new cohort of patients in whom tumor grade is a very important prognostic variable.

Rectal cancer: review with emphasis on MR imaging

One concern after rectal cancer surgery is the high local recurrence rate. Randomized trials have shown that the best local control rate for rectal cancer patients as a group is achieved after a short course of radiation therapy followed by optimal surgery. It is debatable, however, whether all patients with rectal cancer should undergo preoperative radiation therapy. Preoperative identification of those most likely to benefit from neoadjuvant therapy is important. Therefore, the challenge for preoperative imaging in rectal cancer is to determine subgroups of patients with different risks for recurrence: those with superficial tumors, who can be treated with surgery alone; those with operable tumors and a wide circumferential resection margin, who can be treated with a short course of radiation therapy followed by total mesorectal excision; and those with advanced cancer and a close or involved resection margin, who require a long course of radiation therapy, with or without chemotherapy, and extensive surgery. So far, there is no consensus on the role of diagnostic imaging (endorectal ultrasonography, computed tomography, and magnetic resonance [MR] imaging) in the care of patients with primary rectal cancer. Preoperative staging has long relied on digital examination alone, which indicates that it has been difficult to achieve accuracy levels high enough for clinical decision making with preoperative imaging. In this review, the relevance of preoperative imaging in staging the local extent of primary rectal cancer will be discussed. Research on various imaging modalities, with an emphasis on MR, will be discussed under four main headings that address the most relevant aspects of local spread of rectal tumors: T stage, circumferential resection margin, locally advanced rectal cancer, and N stage.

[F-18] fluorodeoxyglucose positron emission tomography as a tool for early recognition of incomplete tumor destruction after radiofrequency ablation for liver metastases

BACKGROUND AND OBJECTIVES

To assess the value of FDG positron emission tomography (PET) for early detection of incomplete tumor destruction after radiofrequency ablation (RFA) for liver metastasis.

METHODS

Twenty-eight unresectable liver metastases in 17 patients were treated by RFA. Patients underwent computed tomography (CT) and FDG-PET preoperatively, at 1 week, 1 month, and 3 months postoperatively. Postoperative CT and FDG-PET at 1 week and 1 month were analyzed to identify hypervascular and hypermetabolic residual tumors at the RFA site. These results were correlated with follow-up CT and, in case of reintervention, with pathologic results.

RESULTS

In 24/28 of RFA-treated metastases, CT and FDG-PET at 1 week and 1 month showed no tumor residues. During follow-up, none of these 13 patients developed local recurrence at RFA site. In four patients, FDG-PET at 1 week and 1 month showed peripheral hypermetabolic residue after RFA, whereas CT did not revealed residual tumor. In three patients, local persistence of viable tumor cells was biopsy-proven at reintervention. In the fourth, follow-up CT showed subsequent development of a local recurrence.

CONCLUSIONS

FDG-PET accurately monitors the local efficacy of RFA for treatment of liver metastases, as it early recognizes incomplete tumor ablation, not detectable on CT.

Impact of positron emission tomography on strategy in liver resection for primary and secondary liver tumors

PURPOSE

Outcome of patients with metastatic disease mainly depends on accurate preoperative tumor staging. 18[F]fluorodeoxyglucose positron emission tomography (18F-PET) has been proven to be a valuable diagnostic tool in a number of different tumors but its direct influence on liver surgery has not been thoroughly investigated.

MATERIALS AND METHODS

Between July 1999 and March 2000, 50 consecutive patients with 174 suspected liver lesions were admitted to the University Hospital Jena. All 50 patients underwent abdominal ultrasound, CT-scan, and 18-FDG positron emission tomography scanning. In 23 patients the diagnostic work-up was completed by MRI scan.

RESULTS

Altogether there were a total of 174 histologically proven intrahepatic lesions, nine of which were benign. The sensitivity, specificity, and positive predictive value of PET for all hepatic lesions was 82%, 25%, and 96% compared with 63%, 50%, and 96% for abdominal ultrasound, 71%, 50%, and 97% for CT-scan, and 83%, 57%, and 97% for MRI-scan. In 23 of 50 patients 24 extrahepatic lesions were identified. In these patients the sensitivity and specificity of PET-compared to abdominal ultrasound, CT-scan, and MRI-scan for all extrahepatic lesions-was 63% and 60%, 29% and 25%, 47% and 50% and 40% and 50%, respectively. The findings on PET scan had a direct impact on operative management in nine patients (18%).

CONCLUSIONS

Our series demonstrates good sensitivity and specificity for the detection of primary and secondary liver lesions which is superior to ultrasound and CT scan but not to MRI scan. The main value of PET scan consists in the detection of extrahepatic tumor (64%). Due to better detection of extrahepatic tumor, FDG-PET is a very useful addition to the currently used anatomically-based images in all cases of advanced tumor spread with high risk of extrahepatic tumor.

The role of positron emission tomography in the management of colorectal cancer

Positron emission tomography (PET) is a functional imaging modality that has made the transition from the research environment to the clinical environment over the last 10 years. Its major role is in the field of oncology where it is being used increasingly in the management of several tumour types including colorectal cancer. This review aims to outline the current and future role of PET scanning in the field of colorectal cancer.

FDG-PET scanning in the diagnosis of gastrointestinal cancers

This review deals with the current, well-established indications for two-(18F)-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) scanning in patients with gastrointestinal cancers. FDG-PET is a non-invasive, functional imaging technique. FDG exploits the native glucose transporter to enter the cell. Since many tumours have enhanced glucose uptake, FDG is readily accumulated in malignant cells and can be detected by a PET camera. FDG-PET has been established as an important diagnostic tool in clinical oncology. This review deals with the current, well-established indications for FDG-PET scanning in patients with gastrointestinal cancers. In the current practice, FDG-PET is most commonly used to stage oesophageal carcinoma, to detect and stage recurrence of colorectal carcinoma and to differentiate between benign and malignant pancreatic lesions. The benefit of FDG-PET scanning in patients with oesophagus carcinoma is best established in stage IV disease, as the diagnostic accuracy to detect metastatic disease is higher compared to the combination of computed tomography (CT) and endoscopic ultrasound (EUS). In patients with a history of colorectal carcinoma, FDG-PET scanning is particularly effective in diagnosing recurrent disease, especially in those with a rising carcinoembryonic antigen without a suspect lesion on conventional imaging. Large series have indicated that the sensitivity and specificity for detecting recurrent colorectal carcinoma are in the range of 87%-100% and 66%-100%, respectively. Equally, FDG-PET has a high sensitivity (68%-96%) and specificity (78%-100%) in detecting pancreatic carcinoma in patients with a suspicious-looking pancreatic mass on CT scan. Lastly, we focus on the use of FDG-PET as a modality for early monitoring of treatment response in patients with gastrointestinal stromal cell tumours. Without doubt, future developments will further establish the diagnostic role of the FDG-PET scan in the care of patients with gastrointestinal cancers.

Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT): Clinical Applications

Positron emission tomography and single-photon emission computed tomography are nuclear imaging modalities that excel in depicting the biological function of tissue. Unlike structural imaging methods, they provide functional diagnostic information about brain neoplasms, stroke, neurodegenerative disorders, epilepsy, cortical visual loss, and migraine.

Positron emission tomography affects surgical management in recurrent colorectal cancer patients

BACKGROUND

We determined the effect of positron emission tomography (PET) on surgical decision-making in patients with metastatic or recurrent colorectal cancer.

METHODS

A total of 114 patients with advanced colorectal cancer were imaged with computed tomography (CT) and PET scans. The PET and CT scans were independently interpreted before surgery and recorded.

RESULTS

Forty-two of the 114 patients had resectable disease on the basis of CT. PET altered therapy in 17 (40%) of these 42 patients on the basis of the following results: extrahepatic disease (n = 9), bilobar involvement (n = 3), thoracic involvement (n = 5), retroperitoneal lymphadenopathy (n = 2), bone involvement (n = 1), and supraclavicular disease (n = 1). In 25 patients with liver metastases only, PET found additional disease in 18 (72%), extrahepatic disease in 11, chest disease in 13, retroperitoneal lymphadenopathy in 4, and bone disease in 3. In five patients, both scans underestimated small-volume peritoneal metastases discovered at laparotomy.

CONCLUSIONS

PET altered therapy in 40% of patients. In patients with isolated liver involvement, 72% had more extensive disease that precluded surgical resection. PET scans should be used in the management of patients with recurrent colorectal cancer who are being considered for potentially curative surgery.

Management of colorectal liver metastases

Hepatic metastases occur in 60% of patients following resection for colorectal cancer. Liver resection is the only curative option, with one third of resected patients alive at five years. In those developing recurrence in the liver following resection, further liver surgery may be curative, with similar 5 years survival rates of about 30%. Until recently surgery was feasible in only 15-25% of patients with colorectal liver metastases. New strategies, such as downstaging chemotherapy, portal vein embolization and two-stage hepatectomy, may increase the resectability rate by 15%. Earlier detection of liver metastases would increase resectability, although good follow-up trials are lacking. Once suspected, colorectal liver metastases are staged by spiral CT, CT portography and MRI, which have similar overall accuracies. Mortality following liver resection is less than 5% in major centres, with a morbidity rate of 20% to 50%. Prognostic scoring systems can be used to predict the likely cure rate with resection. Pulmonary metastases occur in 10-25% of patients with resected colorectal cancer, but are limited to the lung in only 2% of cases. In these selected cases surgery provides long-term survival in 20-40%, and repeat lung resection has shown similar rates. For patients with unresectable disease, chemotherapy and ablation techniques have been demonstrated to prolong survival, although chemotherapy alone has been shown to improve quality of life.

Ferumoxide-enhanced magnetic resonance imaging techniques in pre-operative assessment for colorectal liver metastases

AIM

The objective was to evaluate whether contrast-enhanced magnetic resonance imaging (MRI) techniques used in a pre-operative assessment protocol for colorectal liver metastases are as accurate as spiral computer tomography during arterial portography (CTAP). Pre-operative accuracy and clinical consequences of MRI are described and compared with CTAP. Moreover, post-operative survival rate and tumour recurrence were studied.

METHODS

The study group comprised 84 patients which were possible candidates for a partial hepatectomy for colorectal liver metastases. Patients were pre-operatively evaluated by CT of the abdomen, CT of the thorax and spiral CTAP and ferumoxide-enhanced MRI was performed in routine way for all patients. Following this selection, 35 patients underwent a partial hepatectomy with curative intent. All patients were retrospectively evaluated.

RESULTS

Ferumoxide-enhanced MRI proved to be at least as accurate as spiral CTAP in 81% of patients. In nine patients (11%) spiral CTAP revealed more intrahepatic lesions than MRI; in only two patients (2%) did these foundings influenced the clinical decision. These patients were considered to have irresectable disease. In seven patients (8%) MRI detected more lesions than spiral CTAP and influenced the clinical decision in three patients (4%) and these did not undergo a laparotomy. The actuarial 3 year overall survival of operated patients was 41% and the actuarial 3 year disease-free survival was 19%.

CONCLUSION

Evaluation of the clinical impact of a pre-operative assessment protocol extended with ferumoxide MRI techniques demonstrated that this non-invasive MRI technique is safe and at least as accurate as spiral CTAP. This MRI technique results in comparable clinical decisions and outcome after hepatectomy. We suggest that the performance of routine contrast-enhanced MRI should instead be used in the pre-operative evaluation of colorectal liver metastases.

Positron emission tomography in colorectal cancer

Positron emission tomography (PET) using (18)F-fluorodeoxyglucose (FDG) is increasingly used in the diagnostic management of colorectal cancer patients. It provides a highly sensitive and specific diagnosis which is entirely based upon alterations of the glucose metabolism found in malignant tissues. The information provided by FDG-PET is independent of the underlying structural characteristics of the lesions and, therefore, it is essentially complementary to the available structural imaging modalities such as CT, MRI and (endoscopic) ultrasound. Several studies have now been performed on the use of FDG-PET in colorectal adenocarcinoma for primary pre-operative staging, for diagnosis and (re)staging of recurrent disease, for localization and staging of occult recurrent disease, and for the assessment of the metabolic effects of chemotherapy and radiotherapy. This chapter aims to clarify some fundamental issues of both detection device and radiotracer, the proven indications for FDG-PET, the strength and limitations of the technique, and how its implementation would affect patient management.