Detection of hepatic metastases from cancers of the gastrointestinal tract by using noninvasive imaging methods (US, CT, MR imaging, PET): a meta-analysis

Staging and follow-up of gastrointestinal tumors with PET/CT

Positron emission tomography (PET) is a functional imaging modality that has been documented to be useful in patient care. Oncologic PET imaging is used for a wide variety of neoplasms, mainly for staging and follow-up, differentiation of equivocal morphologic findings, therapy stratification, and monitoring. Because PET imaging is based on the physiologically mediated distribution of the administered tracer but not on anatomic information, the addition of computed tomography (CT) to PET may improve the interpretation of PET. Combined PET and CT offers several potential advantages over PET alone that may influence the clinical routine. PET/CT was introduced into clinical use only 3 years ago and has found widespread application within only 1 to 2 years. This article summarizes preliminary data of clinical applications for PET/CT in gastrointestinal tumors.

Colorectal cancer follow-up: Useful or useless?

Follow-up of surgically treated colorectal cancer patients is not supported by objectively certain data. Despite the thousands of investigations reported in the scientific literature, only six randomized prospective studies and two meta-analysis of randomized studies provide data suggesting clear conclusions. Our review of the literature revealed that intensive colorectal follow-up should be performed even if the long-term survival benefit is small. The timing and investigations conducted in follow-ups diverge. The inconsistency of follow-ups is revealed by the fact that the leading USA and European societies propose different guidelines. One datum that the literature agrees on is that pancolonoscopy performed at 3-5 year intervals in colorectal cancer surgery patients supports diagnosis of adenomatous polyps and metachronous cancers. Cost analysis have shown that intensive follow-up would certainly exceed the cut-off point level set for every additional year of good quality of life.

Diffusion-weighted imaging of the liver: technical challenges and prospects for the future

Diffusion-weighted imaging (DWI) has recently been attempted in the abdominal region. We review diffusion-weighted images of the liver, especially from the technical point of view. We discuss selection of pulse sequence parameters, effects of anti-breathing motion technique, tips for measuring apparent diffusion coefficient (ADC), and utility of superparamagnetic iron oxide (SPIO), showing clinical cases, including those at 3T. Our current trial of new pulse sequencing, such as SPIO-mediated breath-holding black-blood fluid-attenuated inversion recovery (BH-BB-FLAIR), imaging is shown. Some prospects for the future in DWI of the liver are also stated.

Is routine magnetic resonance imaging justified for the early detection of resectable liver metastases from colorectal cancer?

PURPOSE

This study was designed to determine whether routine follow-up by magnetic resonance imaging improves the detection of resectable liver metastases from colorectal cancer and patients' survival.

METHODS

Patients who underwent curative surgery for colorectal cancer were included in a program of liver surveillance by routine magnetic resonance imaging, in addition to the standard follow-up protocol consisting of clinical examination and biochemical tests. The median follow-up was 41 (interquartile range, 30-53) months, with a median magnetic resonance imaging surveillance period of 20 (interquartile range, 12-27) months. Cases were analyzed for mode of diagnosis, resectability, and overall survival.

RESULTS

Liver metastases were found in 37 (13 percent) of 293 patients studied. Magnetic resonance imaging diagnosed hepatic metastases with 84 percent sensitivity and 90 percent specificity. In 28 (76 percent) patients, carcinoembryonic antigen and/or liver function tests were abnormally elevated and 5 patients (14 percent) were symptomatic. Hepatic resection was possible in only nine patients (24 percent). Magnetic resonance imaging detected all resectable cases, whereas traditional follow-up would have missed three (33 percent) cases suitable for surgery.

CONCLUSIONS

Although magnetic resonance imaging surveillance increased the number of patients suitable for liver resection by 50 percent, these represented only 1 percent of the patients included in the study. Whether these results are enough to justify the allocation of expensive resources is controversial.

Treatment of hepatic metastases from colorectal cancer: Many doubts, some certainties

About 50% of patients with colorectal cancer (CCR) are destined to develop hepatic metastases during the course of the disease. Surgery is currently the only potentially curative treatment with a five year survival rate after hepatectomy from 26% to 49%. The criteria for resectability are now less rigid than in the past and the tendency to adopt a more aggressive treatment of metastatic lesions is the rule. Systemic infusion chemotherapies based on 5-fluorouracil (5-FU), oxaliplatin (OHP) and irinotecan (CPT-11) are well tolerated and have been shown to be effective in non-operable patients. These regimens allow surgery for patients who are initially not suitable for resection, giving them a probability of survival at five years similar to that of patients operated on at diagnosis. Intra-arterial infusion chemotherapy (HAI) is very effective in inducing objective responses, but is costly, difficult to manage and encumbered by major side effects, so that its application is necessarily limited to centres with specific experience. However, despite the broader criteria and recent advances of chemotherapy, surgery is not possible in most patients. The role of other local therapeutic techniques like cryosurgery (CS) and radiofrequency ablation (RF), alone or combined with surgery or chemotherapy, is not yet established in a multidisciplinary therapeutic approach. Roughly two thirds of patients relapse during the first two years after surgery suggesting appropriate post-operative chemotherapy treatment after hepatic resection may be indicated, but no randomised studies have been published to date. In case of relapse, another hepatectomy should be considered. The role of novel targeted therapies in pre-operative, post-operative and palliative management has yet to be evaluated.

CT and PET in stomach cancer: preoperative staging and monitoring of response to therapy

Stomach cancer is one of the leading causes of cancer mortality worldwide. Complete resection of a gastric tumor and adjacent lymph nodes represents the only potentially curative intervention. Computed tomography (CT) has remained the modality of choice for the preoperative staging of gastric cancer and for follow-up. A recently developed advanced CT technique that makes use of thin sections, optimal contrast material enhancement, and multiplanar reformation allows more accurate staging. However, CT may be limited in the identification of nonenlarged lymph node metastasis, peritoneal dissemination, and small hematogenous metastasis. Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) has been recognized as a useful diagnostic technique in clinical oncology. FDG PET allows scanning of a larger volume than is possible with CT. Although FDG PET is not an appropriate first-line diagnostic procedure in the detection of stomach cancer and is not helpful in tumor staging, it may play a valuable role in the detection of distant metastases, such as those of the liver, lungs, adrenal glands, ovaries, and skeleton. FDG PET may also be helpful in the follow-up of patients undergoing chemotherapy, as it allows the identification of early response to treatment. Further studies are needed to determine the efficacy of FDG PET in the detection of local nodal metastases and peritoneal dissemination. Nevertheless, the combined use of CT and PET can be helpful in the preoperative staging of stomach cancer and in the therapeutic monitoring of affected patients.

PET imaging for evaluation of metastatic colorectal cancer of the liver

Colorectal cancer is a major cause of cancer death in Western Europe and United States; the liver is the most common site for colorectal metastases. PET has an important role in the management of patients with colorectal liver metastases. It is an effective tool to detect hepatic metastases and to monitor the response to systemic and local therapy. The major impact of PET-CT over PET alone is the improvement in the certainty of lesion location. PET-CT has the unique advantage to combine functional and anatomic imaging in an integrated scanner; it allows a thoroughly evaluation of patients with colorectal liver metastases.

Diagnostic precision of nanoparticle-enhanced MRI for lymph-node metastases: a meta-analysis

BACKGROUND

At present, there is no accepted, ideal imaging modality or technique for diagnosis of lymph-node metastases. We aimed to assess the diagnostic precision of MRI with ferumoxtran-10-an ultrasmall superparamagnetic iron-oxide nanoparticle used as a contrast agent for diagnosis of lymph-node metastases, compared with that of unenhanced MRI and final histological diagnosis.

METHODS

We did a meta-analysis of prospective studies that compared MRI, with and without ferumoxtran-10, with histological diagnosis after surgery or biopsy. Sensitivity, specificity, and diagnostic odds ratio (DOR) were calculated for every study; summary receiver operating characteristic (ROC) and subgroup analyses were done; and study quality and heterogeneity were assessed. Metaregression analysis was used to analyse the effect of ferumoxtran-10 in diagnostic precision of MRI.

FINDINGS

Summary ROC curve analysis for per-lymph-node data showed an overall sensitivity of 0.88 (95% CI 0.85-0.91) and overall specificity of 0.96 (0.95-0.97) for ferumoxtran-10-enhanced MRI. Overall weighted area under the curve for ferumoxtran-10-enhanced MRI was 0.96 (SE 0.01), DOR 123.05 (95% CI 5.93-256.93). Unenhanced MRI had less overall sensitivity (0.63 [0.57-0.69]) and specificity (0.93 [0.91-0.94]), with an overall weighted area under the ROC curve of 0.84 (SE 0.11) and DOR of 26.75 (95% CI 8.48-84.42). Significant heterogeneity was noted for studies reporting enhanced MRI and unenhanced MRI. Metaregression analysis confirmed the significant effect of ferumoxtran-10 in the diagnostic precision of MRI (p=0.001).

INTERPRETATION

Ferumoxtran-10-enhanced MRI is sensitive and specific in detection of lymph-node metastases for various tumours. It offers higher diagnostic precision than does unenhanced MRI for detection of lymph-node metastases, and allows functional and anatomical definition when used as an imaging modality.

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 impact of intra operative ultrasound in metastases liver surgery]

BACKGROUND

Twenty-five to 50% of the patients with hepatic metastases are potential candidates for curative surgery. Intraoperative ultrasound has been employed to guide the surgery.

AIM

To evaluate this method in liver surgeries and compare it to other imaging methods.

PATIENTS AND METHODS

Thirty-five patients (20 females, with median age of 56 years) with hepatic metastases were prospectively studied between February 2001 and July 2003. Patients had as primary tumors: colorectal cancer (24), neuroendocrine tumors (3), renal cell carcinoma (2), melanoma (2), others (4). Each patient was submitted to at least: computed tomography (30), ultrasonography (14) and magnetic resonance imaging (8). Intraoperative ultrasound was performed in all patients in order to detect liver nodules. The number and location of liver lesions were compared to preoperative results.

RESULTS

Intraoperative ultrasound was useful in 23 (65.6%) of the 35 surgeries and changed the planned surgical strategy in 9 (25.7%). There was a statistical significant correlation between the mean number of nodules identified by ultrasonography, computed tomography, magnetic resonance imaging and intraoperative ultrasound. We found no statistical difference between magnetic resonance imaging and intraoperative ultrasound in identifying hepatic nodules. Fifty-five nodules were submitted to histological evaluation, the gold standard method and 52/55 (94.5%) were identified by intraoperative ultrasound. Intraoperative ultrasound identified 91.6% of the smaller than 1.5 cm lesions, ultrasonography identified 15.0% of them, computed tomography 33.3% and magnetic resonance imaging 66.6%.

CONCLUSIONS

Intraoperative ultrasound is crucial in the evaluation and decision making in hepatic surgery. Intraoperative ultrasound presents the highest sensibility in the detection of hepatic nodules compared to other imaging methods, especially for small lesions.

Liver metastases of colorectal cancer: US, CT or MR?

In contrast to other extrahepatic malignancies many colorectal cancers can be cured even when there is metastatic spread to the liver. The diagnosis of liver metastases relies totally on imaging to decide which patients may be surgical candidates. The diagnostic value of ultrasound with contrast agents, multidetector CT and MR imaging with non-specific gadolinium chelates and liver-specific contrast agent is discussed. Nowadays MDCT is the mainstay of staging and follow-up of these patients, because it provides good coverage of the liver and the complete abdomen and the chest in one session. MR imaging has been shown to be superior to helical CT in the preoperative assessment of colorectal liver metastases. Large studies are needed to define the role of MDCT vs. MRI staging in patients referred for resection of liver metastases.

Colorectal cancer: what the clinician wants to know

Colorectal cancer is a common and lethal disease. The adenoma-carcinoma sequence offers a window of opportunity in which the precursor lesion or early carcinoma can be removed endoscopically to prevent systemic disease. New and advanced techniques to improve endoscopic detection of precursor lesions are being developed. Other, less invasive screening methods are currently being developed and may become of use for population-based screening in the near future. Recently, important developments in the treatment (both surgical and chemotherapeutic) of colorectal cancer have occurred. The extent of the disease (stage) forms the basis for therapeutic decisions and accurate imaging is crucial.

A metaanalysis of 18F-2-deoxy-2-fluoro-D-glucose positron emission tomography in the staging and restaging of patients with lymphoma

BACKGROUND

In recent years, the use of positron emission tomography (PET) has become widespread for the staging and follow-up of several malignancies. In the current study, the authors conducted a metaanalysis of the published literature to evaluate the diagnostic performance of 18F-2-deoxy-2-fluoro-D-glucose PET (FDG-PET) in the staging of patients with lymphoma.

METHODS

The authors conducted a systematic MEDLINE search of articles published between January 1995 and June 2004. Studies that evaluated FDG-PET with a dedicated camera and that reported sufficient data to permit the calculation of sensitivity and specificity were included in the analysis. Two reviewers independently reviewed the eligibility of the studies and abstracted data (sample population; characteristics of FDG-PET; and the number of true-positive results, true-negative results, false-positive results, and false-negative results). The authors estimated the pooled sensitivity, false-positive rate, and maximum joint sensitivity and specificity.

RESULTS

Twenty studies were eligible for the metaanalysis. Fourteen studies included patient-based data, comprising a sample size of 854 subjects, and 7 studies included lesion-based data, totaling 3658 lesions. Among those studies with patient-based data, the median sensitivity was 90.3% and the median specificity was 91.1%. The pooled sensitivity was 90.9% (95% confidence interval [95% CI], 88.0-93.4) and the pooled false-positive rate was 10.3% (95% CI, 7.4-13.8). The maximum joint sensitivity and specificity was 87.8% (95% CI, 85.0-90.7). The pooled sensitivity and false-positive rate appeared to be higher in patients with Hodgkin disease compared with those with non-Hodgkin lymphoma.

CONCLUSIONS

The results of the current study indicate that FDG-PET is a valuable tool for the staging and restaging of patients with lymphoma; showing a high positivity and specifity. Clinicians may consider adding FDG-PET to the staging workup of patients with lymphoma.

Diffusion-weighted images of the liver: comparison of tumor detection before and after contrast enhancement with superparamagnetic iron oxide

PURPOSE

To study the recognition of malignant lesions of the liver on diffusion-weighted images (DWI) can be improved by the administration of superparamagnetic iron oxide (SPIO).

MATERIALS AND METHODS

Pre- and post-SPIO mediated DWI of the liver was compared in six patients with suspected malignant liver lesions at 1.5 Tesla using a parallel imaging technique.

RESULTS

Post-SPIO DWI showed improved contrast-to-noise ratio between malignant lesions and liver. Furthermore, the spleen signal was decreased on post-SPIO DWI, thus avoiding the overlap of the spleen and left lobe of the liver on maximum intensity projections (MIP).

CONCLUSION

Recognition of malignant lesions of the liver was improved by SPIO on DWI. On MIP images of DWI, SPIO helped to decrease the overlap of spleen signal on the liver in some projection angles.

Applications of PET in Liver Imaging

Fluorodeoxyglucose PET (FDG-PET) imaging has an important role in determining if there are metastases to the liver and whether disease has spread beyond the liver. Such information is critical for planning surgical resections of liver metastases. The ability of FDG-PET quantitatively to estimate metabolic rates makes it an important tool for monitoring. With increasingly broad indications for FDG-PET imaging, it is expected that FDG-PET (and PET-CT) of the liver will play a growing and increasingly important role in detecting and monitoring treatment of tumors involving the liver.

Colorectal liver metastases: CT, MR imaging, and PET for diagnosis--meta-analysis

PURPOSE

To perform a meta-analysis to obtain sensitivity estimates of computed tomography (CT), magnetic resonance (MR) imaging, and fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) for detection of colorectal liver metastases on per-patient and per-lesion bases.

MATERIALS AND METHODS

MEDLINE, EMBASE, Web of Science, and CANCERLIT databases and Cochrane Database of Systematic Reviews were searched for relevant original articles published from January 1990 to December 2003. Criteria for inclusion of articles were as follows: Articles were reported in the English, German, or French language; CT, MR imaging, or FDG PET was performed to identify and characterize colorectal liver metastases; histopathologic analysis (surgery, biopsy, or autopsy), intraoperative observation (manual palpatation, intraoperative ultrasonography [US]), and/or follow-up US was the reference standard; and data were sufficient for calculation of true-positive or false-negative values. A random-effects linear regression model was used to obtain sensitivity estimates in assessment of liver metastases.

RESULTS

Of 165 identified relevant articles, 61 fulfilled all inclusion criteria. Sensitivity estimates on a per-patient basis for nonhelical CT, helical CT, 1.5-T MR imaging, and FDG PET were 60.2%, 64.7%, 75.8%, and 94.6%, respectively; FDG PET was the most accurate modality. On a per-lesion basis, sensitivity estimates for nonhelical CT, helical CT, 1.0-T MR imaging, 1.5-T MR imaging, and FDG PET were 52.3%, 63.8%, 66.1%, 64.4%, and 75.9%, respectively; nonhelical CT had lowest sensitivity. Estimates of gadolinium-enhanced MR imaging and superparamagnetic iron oxide (SPIO)-enhanced MR imaging were significantly better, compared with nonenhanced MR imaging (P = .019 and P < .001, respectively) and with helical CT with 45 g of iodine or less (P = .02 and P < .001, respectively). For lesions of 1 cm or larger, SPIO-enhanced MR imaging was the most accurate modality (P < .001).

CONCLUSION

FDG PET had significantly higher sensitivity on a per-patient basis, compared with that of the other modalities, but not on a per-lesion basis. Sensitivity estimates for MR imaging with contrast agent were significantly superior to those for helical CT with 45 g of iodine or less.

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.

Detection of recurrent pancreatic cancer: comparison of FDG-PET with CT/MRI

OBJECTIVE

To determine the value of fluorine-18-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) for the detection of recurrent pancreatic cancer in comparison to computed tomography (CT) and magnetic resonance imaging (MRI).

METHODS

Thirty-one patients with suspected recurrence after surgery were included. Inclusion criteria were sudden weight loss, pain or increased CA 19-9 levels. FDG-PET was performed in all patients. After visual analysis, maximal standardized uptake values (SUVmax) were determined by placing regions of interest on the pancreas bed. Additionally, all patients underwent contrast-enhanced multidetector CT (n = 14) or MR (n = 17) imaging. Positive findings at FDG-PET or CT/MRI were compared to follow-up.

RESULTS

All patients relapsed. Of 25 patients with local recurrences upon follow-up, initial imaging suggested relapse in 23 patients. Of these, FDG-PET detected 96% (22/23) and CT/MRI 39% (9/23). Local SUVmax ranged from 2.26 to 16.9 (mean, 6.06). Among 12 liver metastases, FDG-PET detected 42% (5/12). CT/MRI detected 92% (11/12) correctly. Moreover, 7/9 abdominal lesions were malignant upon follow-up of which FDG-PET detected 7/7 and CT/MR detected none. Additionally, FDG-PET detected extra-abdominal metastases in 2 patients.

CONCLUSION

In patients suspected of pancreatic cancer relapse; FDG-PET reliably detected local recurrences, whereas CT/MRI was more sensitive for the detection of hepatic metastases. Furthermore, FDG-PET proved to be advantageous for the detection of nonlocoregional and extra-abdominal recurrences.

Evaluation of Liver Metastases After Radiofrequency Ablation: Utility of18F-FDG PET and PET/CT

OBJECTIVE

Our objective was to review the CT appearance of liver metastases after radiofrequency ablation and to describe the imaging findings of and utility of (18)F-FDG PET and PET/CT in assessing tumor recurrence after ablation.

CONCLUSION

(18)F-FDG PET and PET/CT can provide added diagnostic information compared with conventional imaging in patients after radiofrequency ablation of liver metastases and can be useful in guiding repeat ablation procedures.

The value of vesicant 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in gastric malignancies

AIM

The value of vesicant 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in the detection and staging of primary gastric malignancies was studied prospectively.

METHODS

Thirty-eight patients with suspected gastric tumour were imaged with three-dimensional PET after the injection of 18F-FDG. During the PET study, vesicant was given orally in order to extend the stomach with CO(2) gas. Surgical operation (n=31) or gastric endoscopy with biopsy (n=7) was undertaken 3-26 days after the PET study. The PET results were compared with clinical (computed tomography/magnetic resonance imaging/ultrasound), surgical and histological staging.

RESULTS

PET correctly diagnosed 83.3% of primary malignant (25/30) and benign (7/8) lesions, and corrected 11 clinically and five surgically mis-staged cases. Five primaries were false-negatives in quantitative analysis, but qualitative PET readings revealed positive lymph nodes, thereby providing a correct diagnosis in two of the five. PET misdiagnosed seven N1, one N2 and one false-positive case. The focal uptake of 18F-FDG was correlated with the differentiation, size and depth of invasion of the gastric tumours.

CONCLUSIONS

18F-FDG PET is useful for the detection and staging of primary gastric malignancies, and the administration of vesicant may improve the diagnostic confidence.

Preoperative evaluation and postoperative follow-up for patients with rectal cancer

Rectal cancer has a wide variety of presentations. In most cases, it is the surgeon who is faced with the challenge of determining the extent of disease and advising the patient how to proceed with treatment. Utilizing diagnostic tests of the highest accuracy and relevance will help in the selection of the best initial therapy, which is critical for achieving the highest cure rate while also avoiding over-treatment and unnecessary morbidity. Following curative treatment, surveillance testing for detection of recurrence is traditionally done, but the efficacy of this practice has been questioned. Surveillance will detect a number of asymptomatic recurrences that are treatable by potentially curative salvage surgery, but to what extent early detection improves salvage therapy is not well established. In this brief review, the goals, methods, and expected benefits of rectal cancer staging and surveillance are assessed.

From colonic polyps to colon cancer: pathophysiology, clinical presentation, and diagnosis

Epidemiologists, basic researchers, clinicians, and public health administrators unite! Develop and implement a simple, safe, and effective preventive and screening test for colon cancer. The public will willingly and enthusiastically accept such a test. Many thousands of lives are at stake every year.

A meta-analysis of FDG-PET for the evaluation of breast cancer recurrence and metastases

OBJECTIVE

To evaluate the diagnostic performance of 18F-2-deoxy-2-fluoro-D-glucose-positron emission tomography (FDG-PET) in the evaluation of breast cancer recurrence and metastases.

DATA SOURCES

Articles published in medical journals during January 1995-June 2004 were identified by a systematic Medline search, supplemented by a manual search of the references listed in original and review articles.

STUDY SELECTION

Studies that evaluated FDG-PET with a dedicated camera for the diagnosis of breast cancer recurrence or metastases, and reporting sufficient data to permit calculation of sensitivity and specificity, were included in the analysis.

DATA EXTRACTION

Two reviewers independently reviewed the eligibility and abstracted data regarding the sample population, technical imaging characteristics of FDG-PET, and the number of true positives, true negatives, false positives and false negatives. Differences between readers were resolved by consensus.

DATA SYNTHESIS

We used meta-analytic methods to estimate the pooled sensitivity, false positive rate, and the maximum joint sensitivity and specificity. Eighteen studies met the inclusion criteria. Sixteen studies included patient-based data, comprising a sample size of 808 subjects, and eight studies included lesion-based data, totaling 1013 lesions. Among the studies with patient-based data, the median sensitivity was 92.7%, and the median specificity was 81.6%. The pooled sensitivity was 90% [95% confidence interval (86.8-93.2)], and the pooled false positive rate was 11% [95% confidence interval (7.8-14.6)], after the exclusion of outliers. The maximum joint sensitivity and specificity, was 88% [95% confidence interval (86.0-90.6)].

CONCLUSION

These results indicate that FDG-PET is a valuable tool for detecting breast cancer recurrence and metastases.

Positron emission tomography/computerized tomography functional imaging of esophageal and colorectal cancer

Positron Emission Tomography/Computerized Emission Tomography (PET/CT) creates fusion images which are a combination of tissue function (PET) and anatomy (CT). PET/CT imaging for esophageal and colorectal cancers improves staging, detection of recurrence, and treatment monitoring. Both tumor types are highly metabolically active in the untreated state, and the glucose analog, 2-[18F]-2-fluoro-2-deoxy-D-glcuose, (FDG), is widely useful as a PET imaging tracer for these malignancies. For esophageal and colorectal malignancies, diagnostic imaging sensitivity and specificity are greater than 90%. For esophageal tumors, PET imaging is standard of care for staging of locally advanced tumor. Fifteen to 20% of patients will have other wise occult metastatic sites detected by PET imaging at initial staging. Progression free survival and survival are correlated with the magnitude of reduction in PET-FDG measured metabolic activity post-treatment. For colorectal cancers, PET-FDG is standard of care to detect recurrence, and to monitor treatment response. The addition of CT to the PET imaging, causes a significant reduction in uncertainty of image interpretation and improves the distinction between benign and malignant causes for FDG-PET positive sites.

Prospective evaluation of the impact of [18F]fluoro-2-deoxy-d-glucose positron emission tomography of resectable colorectal liver metastases

Background

The aim of this study was to assess the additional value of information provided by positron emission tomography (PET) with [18F]fluoro-2-deoxy-d-glucose (FDG) over that provided by computed tomography (CT) in patients with resectable liver metastases from colorectal cancer.

Methods

Between October 2001 and November 2002, a prospective double-blind comparison of preoperative FDG-PET and thoracoabdominal CT was performed in 53 patients with potentially resectable liver metastases from colorectal cancer. All resected metastases were subjected to histological examination.

Results

Histological examination confirmed the presence of malignant or benign lesions detected by PET and/or CT in 95 per cent of instances. Overall sensitivity (78 per cent) and accuracy (88 per cent) of PET were equivalent to those of CT (76 and 86 per cent respectively). The sensitivity of PET was equivalent to that of CT for hepatic sites (both 79 per cent), but was superior for extrahepatic abdominal sites (63 and 25 per cent respectively). PET provided additional information in five patients, mainly by revealing abdominal extrahepatic metastases, but falsely upstaged three patients.

Conclusion

Whole-body FDG-PET may identify unrecognized extrahepatic metastases in patients with potentially resectable liver metastases imaged by CT. However, additional information provided by PET is not as reliable as suggested by earlier retrospective studies.

The incremental effect of positron emission tomography on diagnostic accuracy in the initial staging of esophageal carcinoma

BACKGROUND

The purpose of the current study was to assess whether [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) provides incremental value (e.g., additional information on lymph node involvement or the presence of distant metastases) compared with computed tomography (CT) in patients with esophageal carcinoma.

METHODS

The authors examined 149 consecutive patients with thoracic esophageal carcinoma. Eighty-one patients underwent radical esophagectomy without pretreatment, 17 received chemoradiotherapy followed by surgery, 3 underwent endoscopic mucosal resection, and the remaining 48 patients received definitive radiotherapy and chemotherapy. The diagnostic accuracy of FDG-PET and CT was evaluated at the time of diagnosis.

RESULTS

The primary tumor was visualized using FDG-PET in 119 (80%) of 149 patients. Regarding lymph node metastases, FDG-PET had 32% sensitivity, 99% specificity, and 93% accuracy for individual lymph node group evaluation and 55% sensitivity, 90% specificity, and 72% accuracy for lymph node staging evaluation. PET exhibited incremental value over CT with regard to lymph node status in 14 of 98 patients who received surgery: 6 patients with negative CT findings were eventually shown to have lymph node metastases (i.e., they had positive PET findings and a positive reference standard [RS]); 6 patients with positive CT findings were shown not to have lymph node metastases (i.e., they had negative PET findings and a negative RS); and 2 patients were shown to have cervical lymph node metastases in addition to mediastinal or abdominal lymph node metastases. Among the remaining patients, PET showed incremental value over CT with regard to distant organ metastases in six patients. The overall incremental value of PET compared with CT with regard to staging accuracy was 14% (20 of 149 patients).

CONCLUSIONS

FDG-PET provided incremental value over CT in the initial staging of esophageal carcinoma. At present, combined PET-CT may be the most effective method available for the preoperative staging of esophageal tumors.

Colorectal cancer

Every year, more than 945000 people develop colorectal cancer worldwide, and around 492000 patients die. This form of cancer develops sporadically, in the setting of hereditary cancer syndromes, or on the basis of inflammatory bowel diseases. Screening and prevention programmes are available for all these causes and should be more widely publicised. The adenoma-carcinoma sequence is the basis for development of colorectal cancer, and the underlying molecular changes have largely been identified. Prognosis depends on factors related to the patient, treatment, and tumour, and the expertise of the treatment team is one of the major determinants of outcome. New information on the molecular basis of this cancer have led to the development of targeted therapeutic options, which are being tested in clinical trials. Further clinical progress will largely depend on the broader implementation of multidisciplinary treatment strategies following the principles of evidence-based medicine.

Unusually elevated liver radioactivity on F-18 FDG PET in Hodgkin's disease: hepatic 'superscan'

Increased focal concentration of FDG in the background of relatively lower normal hepatocyte uptake is usually regarded as the hallmark of metastatic involvement of the liver from a known primary. The authors present the clinical, radiologic, and laboratory profile of a very unusual hepatic uptake pattern in a case of Hodgkin disease, in which the FDG PET showed intensely diffuse hepatic tracer uptake and was the earliest indicator of extensive hepatic involvement by the disease process. The diagnosis of hepatic involvement with lymphoma was inferred. As experience with FDG PET is growing, it is important to become familiar with the various physiological and pathologic FDG uptake patterns. The term "hepatic superscan", demonstrating intense diffuse hepatic tracer uptake coupled with surprisingly low brain and cardiac FDG uptake, owes its origin from its apparent similarity with the superscan seen in conventional skeletal scintigraphy and represents an entity hitherto undescribed.

[Whole-body tumor staging: MRI or FDG-PET/CT?]

Technical innovations such as the availability of movable patient platforms and the introduction of 32-channel systems have made whole-body MRI for tumor staging feasible. In addition, the development of dual-modality PET/CT systems offers the opportunity to perform anatometabolic tumor staging with whole-body coverage in a single session. Based on an increase in patient survival when applying a stage-adapted therapy in different malignant diseases the relevant question relates to the accuracies of whole-body MRI and whole-body PET/CT for TNM staging. This review article addresses whole-body tumor staging with MRI and FDG-PET/CT with special emphasis on diagnostic accuracies for staging different malignant diseases.

Diagnostic radiology and nuclear medicine

The diagnosis and accurate staging of esophageal adenocarcinoma remains one of the greatest challenges for non-invasive imaging techniques. All modalities have limitations and require a rational application of combined tools in order to assess the extent of loco-regional tumor and distant metastatic disease. The fundamental role remains defining organ-confined disease and mapping non-organ confined disease. Endoscopic ultrasound combined with multislice computed tomography (CT) is the mainstay of morphologic loco-regional staging. In recent years, functional metabolic 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) has emerged as a particularly useful adjunct to detect occult metastatic disease, to predict response to neoadjuvant therapy and to document recurrent disease. The current imaging algorithm and new developments in imaging assessment will be reviewed.

The pathophysiology, clinical presentation, and diagnosis of colon cancer and adenomatous polyps

A review of the pathophysiology, clinical presentation, and diagnosis of colon cancer and colonic polyps is important and timely. This field is rapidly changing because of breakthroughs in the molecular basis of carcinogenesis and in the technology for colon cancer detection and treatment. This article reviews colon cancer and colonic polyps, with a focus on recent dramatic advances, to help the pri-mary care physician and internist appropriately refer patients for screening colonoscopy and intelligently evaluate colonoscopic findings to reduce the mortality from this cancer.

The use of positron emission tomography in detecting hepatoblastoma recurrence--a cautionary tale

PURPOSE

The use of positron emission tomography (PET) with [18F] fluorodeoxyglucose (FDG) in the detection of recurrences has been well established in many tumor types. Here the authors present their experience using this modality in the evaluation of posttreatment hepatoblastoma patients.

METHODS

The authors conducted a retrospective review on patients with hepatoblastoma diagnosed from 1996 to 2003. FDG-PET imaging was performed together with measurement of alpha-fetal protein (AFP) during posttreatment follow-up.

RESULTS

Sixteen patients (8 boys and 8 girls) were identified in this series. The mean age was 23.5 months (range, 5 months to 4 years). Three posttreatment patients had PET results suggestive of tumor recurrence. One of these patients had normal AFP level and suspected recurrence in the caudate lobe. Radiologic-guided biopsy was performed 3 times, and there was no evidence of tumor. The other 2 patients underwent further liver resections because of mildly raised AFP levels. The histology of these showed regenerative liver tissue only with no hepatoblastoma recurrence.

CONCLUSIONS

Although PET has been gaining popularity as a tool in the detection of tumor recurrences worldwide, it has been shown in this series that PET may not be useful in hepatoblastoma patients, and caution must be taken in the interpretation of positive results.

[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.

Imaging the liver

Imaging of the liver is undertaken for the detection and characterization of suspected primary or secondary neoplasms, prior to planning a surgery or chemotherapy pump placement, for assessing treatment response, for evaluating biliary pathology, and for screening for liver neoplasms in high-risk groups. In this article, we review the advantages and disadvantages of various imaging modalities in the evaluation of the liver and formulate guidelines for the imaging of common clinical indications. A brief review of imaging findings in focal and diffuse liver disease is also presented.

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.

Ganzk�rper-MRT und PET-CT in der Tumordiagnostik

Tumor staging according to the TNM-system influences prognosis and therapeutical options of patients with a malignant disease. It is the challenge of diagnostic imaging to depict the exact localization of the primary tumor and to detect or rule out lymph node involvement or distant metastases. In doing so, the complete body anatomy should be covered with a modality that offers high sensitivity and specificity. As these requirements could not or only partially be achieved by previous ordinary procedures, the use of multiple different modalities became necessary. Last but not least, in consideration of the costs it would be preferable to replace this cascade of different modalities by a "whole body examination", preconditioned that the same accuracy is achieved.With PET/CT and whole-body MRI, two newly available promising methods for a systemic tumor staging have been developed. First experiences indicate PET/CT as a method of first choice. With the introduction of new whole-body MRI scanners using parallel imaging technique (iPAT) and free table movement, MRI plays a more and more important role in whole body tumor staging.

Clinical Decisions Associated With Positron Emission Tomography in a Prospective Cohort of Patients With Suspected or Known Cancer at One United States Center

Purpose

In 2001, Medicare approved reimbursement of F-18 fluorodeoxyglucose positron emission tomography (PET) for a variety of cancers. PET has been observed to be more accurate than other imaging in cancer patients, but the impact of PET on management in routine practice is uncertain.

Patients and Methods

We studied a prospective cohort having noninvestigational PET at one university center. Before and after PET, a questionnaire was administered to solicit information regarding each physician's preceding actions, intended management, and probability estimates.

Results

Seventy-one physicians provided data on 248 patients, of whom 40% had new or suspected cancer and 60% were undergoing restaging or had suspected recurrence. Lung, lymphoma, and head/neck cancers accounted for two thirds of cases. Sixteen physicians made 64% of requests. Physicians changed their intended management in 61% of patients (95% CI, 54% to 66%). For individual physicians ordering at least 10 scans, the average kappa was 0.16 (range, −0.04 to 0.36), reflecting only slight level of agreement between their before and after PET plan. PET was associated with a change in 90 (79%) of 114 patients if the pre-PET intended plan involved more testing or biopsy. In 32% of cases, physicians changed to a treatment from a nontreatment strategy. The therapeutic goal and mode changed in 22 (7%) and 21 cases (8%), respectively.

Conclusion

This study confirms that physicians often change their decision making based on PET. This impact is likely due to combined effects of PET's improved accuracy and reduced physician uncertainty. Physicians may also be overconfident in interpreting PET and use it as the final arbiter after an extensive evaluation in lieu of tissue biopsy.

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.

Role of FDG-PET in the diagnosis and treatment of colorectal liver metastases

Positron emission tomography (PET) using [(18)F]-2-deoxy-2-fluoro-d-glucose (FDG) has emerged as a promising diagnostic modality in recurrent colorectal cancer. Data in the literature show that the addition of FDG-PET changes disease management in up to 30% of patients with potentially resectable liver metastases, mainly by detecting previously unknown extrahepatic disease. Furthermore, FDG-PET is useful in the follow-up of patients who underwent surgical procedures of the liver, since it is exquisitely sensitive in detecting residual or relapse malignancy in scarred liver tissue following both resection and local ablative techniques. For follow-up during systemic therapy, early FDG-PET appears predictive for response to therapy. However, at present, the available data are insufficient to justify the FDG-PET-driven management of patients treated with chemotherapy. FDG-PET and computerized tomography are complimentary techniques in staging and restaging patients with advanced colorectal cancer. The combination of these two modalities significantly impacts upon patient management.

Value of positron emission tomography in the diagnosis of recurrent oesophageal carcinoma

BACKGROUND

Positron emission tomography (PET) with [18F]fluorodeoxyglucose (FDG) might be useful for staging oesophageal squamous cell carcinoma (SCC). FDG-PET may be more accurate than computed tomography (CT) in diagnosing lymph node metastasis. This retrospective study compared the ability of FDG-PET and CT to diagnose recurrent oesophageal carcinoma.

METHODS

Fifty-five patients with thoracic oesophageal SCC who had undergone radical oesophagectomy were studied. The accuracy of FDG-PET and CT in detecting recurrence during follow-up was calculated using data from the first images generated by either modality that suggested the presence of recurrent disease. Lesions deemed to be equivocal on these scans were considered as positive for recurrence.

RESULTS

Twenty-seven of the 55 patients had recurrent disease in a total of 37 organs. Locoregional recurrence was observed in 19 patients (35 per cent). Distant recurrent disease occurred in 15 patients (27 per cent) in 18 organs. Six patients had recurrence in the liver, four in the lung, six in bone and two in distant lymph nodes. FDG-PET showed 96 per cent sensitivity, 68 per cent specificity and 82 per cent accuracy in demonstrating recurrent disease. The corresponding values for CT were 89, 79 and 84 per cent. The sensitivity of FDG-PET was higher than that of CT in detecting locoregional recurrence, but its specificity was lower because of FDG uptake in the gastric tube and thoracic lymph nodes. In distant organs the sensitivity of PET in detecting lung metastasis was lower than that of CT, but its sensitivity for bone metastasis was higher.

CONCLUSION

FDG-PET has a larger field than CT. Combined PET-CT would appear to be an appropriate modality for the detection of recurrent oesophageal cancer.

N/A

N/A

Rectal cancer: local staging and assessment of lymph node involvement with endoluminal US, CT, and MR imaging--a meta-analysis

PURPOSE

To perform a meta-analysis to compare endoluminal ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging in rectal cancer staging.

MATERIALS AND METHODS

Relevant articles published between 1985 and 2002 were included if more than 20 patients were studied, histopathologic findings were the reference standard, and data were presented for 2 x 2 tables; articles were excluded if data were reported elsewhere in more detail. Two reviewers independently extracted data on study characteristics and results. Bivariate random-effects approach was used to obtain summary estimates of sensitivity and specificity for invasion of muscularis propria, perirectal tissue, and adjacent organs and for lymph node involvement. Summary receiver operating characteristic (ROC) curves were fitted for perirectal tissue invasion and lymph node involvement.

RESULTS

Ninety articles fulfilled all inclusion criteria. For muscularis propria invasion, US and MR imaging had similar sensitivities; specificity of US (86% [95% confidence interval [CI]: 80, 90]) was significantly higher than that of MR imaging (69% [95% CI: 52, 82]) (P =.02). For perirectal tissue invasion, sensitivity of US (90% [95% CI: 88, 92]) was significantly higher than that of CT (79% [95% CI: 74, 84]) (P <.001) and MR imaging (82% [95% CI: 74, 87]) (P =.003); specificities were comparable. For adjacent organ invasion and lymph node involvement, estimates for US, CT, and MR imaging were comparable. Summary ROC curve for US of perirectal tissue invasion showed better diagnostic accuracy than that of CT and MR imaging. Summary ROC curves for lymph node involvement showed no differences in accuracy.

CONCLUSION

For local invasion, endoluminal US was most accurate and can be helpful in screening patients for available therapeutic strategies.

Modern hepatic imaging

This article provides a brief overview of the current status of commonly employed diagnostic techniques--US, CT, MR, and PET--for the evaluation of liver metastases and HCC as well as a description of imaging in RF ablation and liver transplantation. The various advantages and limitations of the techniques have been outlined. At the present time, at our center, MRI is used most often to evaluate these liver pathologies, due to its high accuracy for lesion detection and characterization.