Primary and metastatic breast carcinoma: initial clinical evaluation with PET with the radiolabeled glucose analogue 2-[F-18]-fluoro-2-deoxy-D-glucose

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.

Bone imaging in metastatic breast cancer

Bone is the most common site to which breast cancer metastasizes. Imaging-by skeletal scintigraphy, plain radiography, computed tomography, or magnetic resonance imaging-is an essential part, and positron emission tomography or single-photon emission computed tomography have a potential of evaluating bone metastases, but no consensus exists as to the best modality for diagnosing the lesion and for assessing its response to treatment. Imaging bone metastases is problematic because the lesions can be osteolytic, osteoblastic, or mixed, and imaging modalities are based on either direct anatomic visualization of the bone or tumor or indirect measurements of bone or tumor metabolism. Although bone metastases can be treated, their response to treatment is considered "unmeasurable" according to existing response criteria. Therefore, the process by which oncologists and radiologists diagnose and monitor the response of bone metastases needs revision, and the current inability to assess the response of bone metastases excludes patients with breast cancer and bone disease from participating in clinical trials of new treatments for breast cancer. In this review of the MEDLINE literature, we discuss the pros and cons of each modality for diagnosing bone metastases and for assessing their response to treatment and we present a practical approach for diagnosis and assessment of bone metastasis.

Molecular imaging in breast cancer

Since the 1960s, bone scanning has played a major role in the management of breast cancer. In the last decade, however, the role of radionuclide molecular imaging has expanded significantly in the clinical management of breast cancer because of fluorodeoxyglucose positron emission tomography, mammoscintigraphy, and sentinel lymph node techniques. Molecular imaging also is instrumental in drug development,gene therapy, and in basic science research of breast cancer. This article provides a comprehensive review of the role of molecular imaging of breast cancer in clinical practice and reports on the current state of research in this field.

A prospective evaluation of positron emission tomography scanning, sentinel lymph node biopsy, and standard axillary dissection for axillary staging in patients with early stage breast cancer

BACKGROUND

Positron emission tomography (PET) is a noninvasive imaging modality that can detect malignant lymph nodes. This study determined the sensitivity, specificity, predictive values, and likelihood ratios of PET scanning compared with standard axillary lymph node dissection (ALND) and sentinel lymph node biopsy (SLNB) in staging the axilla in women with early stage breast cancer.

METHODS

Women with clinical stage I or II breast cancer had whole body PET scanning before ALND and SLNB, in a prospective, blinded protocol. ALND were evaluated by standard hematoxylin and eosin (H&E) staining techniques, while sentinel nodes were also examined for micrometastatic disease.

RESULTS

A total of 98 patients were recruited. PET compared with ALND demonstrated sensitivity of 0.40 (95% CI, 0.16, 0.68), specificity 0.97 (CI, 0.90, 0.99), positive likelihood ratio 14.4 (CI, 3.21, 64.5), positive predictive value 0.75 (CI, 0.35, 0.97), and false-negative rate of 0.60 (CI, 0.32, 0.84). Test properties were similar for PET compared with sentinel nodes positive by H&E staining. A few false-positive scans (0.028, CI, 0.003, 0.097) were seen. Multiple logistic regression analysis found that PET accuracy was better in patients with high grade and larger tumors. Increased size and number of positive nodes were also associated with a positive PET scan.

CONCLUSIONS

The sensitivity of PET compared with ALND and SLNB was low, whereas PET scanning had high specificity and positive predictive values. The study suggests that PET scanning cannot replace histologic staging in early stage breast cancer. The low rate of false-positive findings suggests that PET can identify women who can forego SLNB and require full axillary dissection.

Current and future uses of positron emission tomography in breast cancer imaging

Positron emission tomography using (18)F-fluorodeoxyglucose (FDG-PET) has been used for the detection, staging, and response monitoring in breast cancer patients. Although studies have proven its accuracy in detection of the primary tumor and axillary staging, its most important current clinical application is in detection and defining the extent of recurrent or metastatic breast cancer and for monitoring response to therapy. PET is complementary to conventional methods of staging in that it provides better sensitivity in detecting nodal and lytic bone metastases; however, it should not be considered a substitute for conventional staging studies, including computed tomography and bone scintigraphy. FDG uptake in the primary tumor carries prognostic information, but the underlying biochemical mechanisms that are responsible for enhanced glucose metabolism have not been completely elucidated. Future work using other PET tracers besides FDG will undoubtedly help our understanding of tumor biology, improve our ability to measure and predict response and help tailor therapy to individual patients.

18F-2-Fluoro-2-Deoxy-d-Glucose Positron Emission Tomography in Staging of Locally Advanced Breast Cancer

Purpose

To prospectively evaluate the effect of adding whole-body 18F-2-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) to conventional screening for distant metastases in patients with locally advanced breast cancer (LABC).

Patients and Methods

All women with LABC referred for participation in the LABC Spinoza trial were considered eligible for this study. Patients were included if chest x-ray, bone scan, liver ultrasound, or computed tomography scan performed by the referring physician failed to reveal distant metastases. They underwent whole-body FDG PET scanning before therapy. Patients with subsequently proven distant metastases were switched to alternative forms of chemotherapy, hormonal therapy, or both.

Results

Among the 48 patients evaluated with PET, 14 had abnormal FDG uptake, and metastases were suspected in 12. After simple clinical evaluation (plain x-ray, history), 10 sites that were suggestive of abnormality remained. Further work-up revealed that four sites were metastases. Proven false positivity occurred in one patient with sarcoidosis. In the other five patients, the reason for abnormal FDG uptake (liver, lung, bone) remained unclear, and patients were treated as planned. Eleven months later, distant metastases were found in one patient at sites unrelated to the previous FDG uptake.

Conclusion

The addition of FDG PET to the standard work-up of patients with LABC may lead to the detection of unexpected distant metastases. This may contribute to a more realistic stratification between patients with true stage III breast cancer and those who are in fact suffering from stage IV disease. Abnormal PET findings should be confirmed to prevent patients from being denied appropriate treatment.

Clinical applications of PET in oncology

Positron emission tomography (PET) provides metabolic information that has been documented to be useful in patient care. The properties of positron decay permit accurate imaging of the distribution of positron-emitting radiopharmaceuticals. The wide array of positron-emitting radiopharmaceuticals has been used to characterize multiple physiologic and pathologic states. PET is used for characterizing brain disorders such as Alzheimer disease and epilepsy and cardiac disorders such as coronary artery disease and myocardial viability. The neurologic and cardiac applications of PET are not covered in this review. The major utilization of PET clinically is in oncology and consists of imaging the distribution of fluorine 18 fluorodeoxyglucose (FDG). FDG, an analogue of glucose, accumulates in most tumors in a greater amount than it does in normal tissue. FDG PET is being used in diagnosis and follow-up of several malignancies, and the list of articles supporting its use continues to grow. In this review, the physics and instrumentation aspects of PET are described. Many of the clinical applications in oncology are mature and readily covered by third-party payers. Other applications are being used clinically but have not been as carefully evaluated in the literature, and these applications may not be covered by third-party payers. The developing applications of PET are included in this review.

Nuclear medicine and breast cancer: a review of current strategies and novel therapies

While breast cancer is still increasing in frequency, new diagnostic procedures are now available to challenge existing procedures and to make diagnosis of breast cancer more accurate and reliable. Mammography remains the standard investigation to reveal disease in an asymptomatic population: it can also be used to diagnose breast cancer in symptomatic patients (e.g. those with palpable breast lumps) and for guiding fine needle aspiration (FNA). Because the majority of breast lumps are benign, the challenge is to distinguish benign from malignant lesions without the use of invasive methods and this has attracted nuclear medicine physicians and medical oncologists to investigate the role of scintigraphic procedures to identify which patients require FNA. This review attempts to shed light on the various scintigraphic methods available which are of potential practical use in the assessment of malignant breast disease as well as looking at the possible role of nuclear medicine in the treatment of advanced disease.

Prospective multicenter study of axillary nodal staging by positron emission tomography in breast cancer: a report of the staging breast cancer with PET Study Group

PURPOSE

To determine the accuracy of positron emission tomography with fluorine-18-labeled 2-fluoro-2-deoxy-d-glucose (FDG-PET) in detecting axillary nodal metastases in women with primary breast cancer.

PATIENTS AND METHODS

In this prospective multicenter study, 360 women with newly diagnosed invasive breast cancer underwent FDG-PET. Images were blindly interpreted by three experienced readers for abnormally increased axillary FDG uptake. Imaging results from 308 assessable axillae were compared with axillary node pathology.

RESULTS

For detecting axillary nodal metastasis, the mean estimated area under the receiver operator curve for the three readers was 0.74 (range, 0.70 to 0.76). If at least one probably or definitely abnormal axillary focus was considered positive, the mean (and range) sensitivity, specificity, and positive and negative predictive values for PET were 61% (54% to 67%), 80% (79% to 81%), 62% (60% to 64%), and 79% (76% to 81%), respectively. False-negative axillae on PET had significantly smaller and fewer tumor-positive lymph nodes (2.7) than true-positive axillae (5.1; P <.005). Semiquantitative analysis of axillary FDG uptake showed that a nodal standardized uptake value (lean body mass) more than 1.8 had a positive predictive value of 90%, but a sensitivity of only 32%. Finding two or more intense foci of tracer uptake in the axilla was highly predictive of axillary metastasis (78% to 83% positive predictive value), albeit insensitive (27%).

CONCLUSION

FDG-PET has moderate accuracy for detecting axillary metastasis but often fails to detect axillae with small and few nodal metastases. Although highly predictive for nodal tumor involvement when multiple intense foci of tracer uptake are identified, FDG-PET is not routinely recommended for axillary staging of patients with newly diagnosed breast cancer.

Role of positron emission tomography in the management of breast cancer

Positron emission tomography (PET) is an imaging modality that utilises tracers based on biologically important compounds and can be used to study in vivo tissue function. This article reviews the current status of PET imaging in breast disease. The positron emitting glucose analogue 18F-FDG is used to image tissue glycolysis and has been extensively evaluated. Studies have shown that 18F-FDG PET has a high sensitivity and specificity for the detection of primary breast cancers, however its use is not superior that of conventional imaging modalities. Considerable interest is now focussing on the application of PET to non-invasively determine the lymph node status of patients with breast cancer and to predict and evaluate tumour response to chemotherapy. Relatively low cost gamma camera systems are now available that are capable of PET imaging, and thus it may therefore be possible to perform PET imaging in the majority of hospitals.

Fluorodeoxyglucose-positron emission tomography in adenocarcinomas of the distal esophagus and cardia

Adenocarcinomas of the esophagogastric junction (AEG) are now recognized as a separate tumor entity with increasing incidence. The aim of the present study was to evaluate whether positron emission tomography (PET) using the glucose analog F-18-fluorodeoxyglucose (FDG) can be used for metabolic characterization of this tumor type. Fifty-two patients with histologically proven, locally advanced AEG (distal esophagus, type I: n = 31; cardia, type II: n = 21) were studied by FDG-PET. None of the tumors had been previously treated. Findings of endoscopy (growth type), endoluminal ultrasound (uT, uN), computed tomography (cN, cranio-caudal extent, tumor thickness), histological evaluation (Lauren classification, tumor grade), anatomical classification, and survival were correlated with the results of FDG-PET. There was no correlation between FDG uptake and clinical stage, grade, Lauren classification, or survival. All AEG I tumors were visualized by FDG-PET with high contrast, whereas FDG uptake by five AEG II tumors (24%) did not differ from background activity. In a quantitative analysis, mean FDG uptake of AEG I tumors was 1.6 times higher than that of AEG II tumors ( p = 0.0005). PET can be used to visualize type I adenocarcinomas of the esophagogastric junction (AEG I). In AEG II tumors, however, the use of FDG-PET appears to be limited. The significantly higher FDG uptake of AEG I tumors compared to AEG II tumors suggests that these two tumor types differ in glucose utilization. This finding strengthens the hypothesis that AEG I and AEG II are two different tumor entities.

Diagnosis of pancreatic cancer using fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) --usefulness and limitations in "clinical reality"

The present review will provide an overview of the literature concerning the FDG PET diagnosis of pancreatic cancer and a summary from our experience of 231 cases of pancreatic lesions. FDG PET can effectively differentiate pancreatic cancer from benign lesion with high accuracy. Newly-developed PET scanners can detect small pancreatic cancers, up to 7 mm in diameter, by their high resolution, which could make a great contribution to the early detection of resectable and potentially curable pancreatic cancers. FDG PET is useful and cost-beneficial in the pre-operative staging of pancreatic cancer because an unexpected distant metastasis can be detected by whole-body PET in about 40% of the cases, which results in avoidance of unnecessary surgical procedures. FDG PET is also useful in evaluation of the treatment effect, monitoring after the operation and detection of recurrent pancreatic cancers. However, there are some drawbacks in PET diagnosis. A relatively wide overlap has been reported between semiquantitative uptake values obtained in cancers and those in inflammatory lesions. As for false-positive cases, active and chronic pancreatitis and autoimmune pancreatitis sometimes show high FDG accumulation and mimic pancreatic cancer with a shape of focal uptake. There were 8 false negative cases in the detection of pancreatic cancer by FDG PET, up to 33 mm in diameter, mainly because of their poor cellularity in cancer tissues. In addition, there are 19% of cancer cases with a decline in FDG uptake from 1 hr to 2 hr scan. FDG PET was recently applied to and was shown to be feasible in the differential diagnosis of cystic pancreatic lesions, such as intraductal papillary mucinous tumor of the pancreas. Further investigations are required to clarify the clinical value of FDG PET in predicting prognosis of the pancreatic patients.

Measuring [(18)F]FDG uptake in breast cancer during chemotherapy: comparison of analytical methods

Over the years several analytical methods have been proposed for the measurement of glucose metabolism using fluorine-18 fluorodeoxyglucose ([(18)F]FDG) and positron emission tomography (PET). The purpose of this study was to evaluate which of these (often simplified) methods could potentially be used for clinical response monitoring studies in breast cancer. Prior to chemotherapy, dynamic [(18)F]FDG scans were performed in 20 women with locally advanced ( n=10) or metastasised ( n=10) breast cancer. Additional PET scans were acquired after 8 days ( n=8), and after one, three and six courses of chemotherapy ( n=18, 10 and 6, respectively). Non-linear regression (NLR) with the standard two tissue compartment model was used as the gold standard for measurement of [(18)F]FDG uptake and was compared with the following methods: Patlak graphical analysis, simplified kinetic method (SKM), SUV-based net influx constant ("Sadato" method), standard uptake value [normalised for weight, lean body mass (LBM) and body surface area (BSA), with and without corrections for glucose (g)], tumour to non-tumour ratio (TNT), 6P model and total lesion evaluation (TLE). Correlation coefficients between each analytical method and NLR were calculated using multilevel analysis. In addition, for the most promising methods (Patlak, SKM, SUV(LBMg) and SUV(BSAg)) it was explored whether correlation with NLR changed with different time points after the start of therapy. Three methods showed excellent correlation ( r>0.95) with NLR for the baseline scan: Patlak10-60 and Patlak10-45 ( r=0.98 and 0.97, respectively), SKM40-60 ( r=0.96) and SUV(LBMg) ( r=0.96). Good correlation was found between NLR and SUV-based net influx constant, TLE and SUV(BSAg) (0.90< r<0.95). The 6P model and TNT had the lowest correlation ( r<or=0.84). SUV was least accurate in predicting changes in [(18)F]FDG uptake over time during therapy. For all methods, correlation with NLR was significantly lower for bone metastases than for other (primary or metastatic) tumour lesions ( P<0.05). In conclusion, three methods with different degrees of complexity appear to be promising alternatives to NLR for measuring glucose metabolism in breast cancer: Patlak, SKM and SUV (normalised for LBM and with a correction for plasma glucose).

Positron emission tomography in diagnosis and management of invasive breast cancer: current status and future perspectives

[18F]fluorodeoxyglucose positron emission tomography (FDG-PET) is a metabolic imaging modality that has increasing applications in oncology, neurology, and cardiology. Among the oncology applications, breast cancer is one of the most extensively studied diseases. FDG-PET has been performed for diagnosis, staging, and restaging of invasive breast cancer and for monitoring responsiveness to therapies. At the present time, the results of FDG-PET in detection of primary breast cancer and axillary staging are mixed and inconclusive. However, results demonstrating the superiority of FDG-PET over anatomic imaging modalities in detection of distant metastasis, recurrence, and monitoring therapies are relatively well documented. These applications have been accepted by medical professionals and the public, as evidenced by a recent decision by the Centers for Medicare and Medicaid Services (formerly Health Care Financing Agency) to provide coverage for the procedure. Future trends in this exciting area include development of novel breast cancer-specific PET radiopharmaceuticals and use of dedicated breast PET technologies for scans of breast/axillary lesions. PET/computed tomography technology, which combines anatomic and molecular/biochemical information, is also rapidly proliferating and should help to further improve the management of patients with breast cancer. The role of FDG-PET in breast cancer is increasing and evolving, and this metabolic imaging modality, in conjunction with newer tracers and other anatomic imaging methods, should improve diagnosis and management of patients with breast cancer

Clinical role of FDG PET in evaluation of cancer patients

Positron emission tomography (PET) is a diagnostic imaging technique that allows identification of biochemical and physiologic alterations in tumors. Use of PET performed with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) significantly improves the accuracy of tumor imaging. In terms of oncologic applications, FDG PET has already gained widespread acceptance in the initial staging of cancer, management of recurrent cancer, and monitoring the response to therapy. With conventional imaging modalities, size criteria are used to distinguish between benign and malignant disease in lymph nodes; conversely, FDG PET is based on identification of fundamental aspects of tumor metabolism. FDG uptake in tumors is proportional to the metabolic rate of viable tumor cells, which have an increased demand for glucose. The high sensitivity and high negative predictive value of FDG PET in most malignant tumors enable this technique to play an even greater role in tumor management at initial staging and follow-up.

Whole-body FDG-PET in patients with stage I non-seminomatous germ cell tumours

Relapse occurs in 30% of patients with stage I non-seminomatous germ cell tumours (NSGCT) within 1 year after orchiectomy. Whole-body positron emission tomography with fluorine-18 fluorodeoxyglucose (FDG-PET) may detect small metastases when standard staging with computed tomography (CT) and tumour markers is negative. In this study, 46 patients underwent FDG-PET after staging with normal CT and tumour markers. To exclude diagnostic test bias and workup bias, all patients had routine follow-up with repeated CT and tumour marker evaluation, even though the initial FDG-PET was positive. Thirty-six patients have remained disease free with a median follow-up of 48 months (range 24-76). Ten patients (22%) suffered disease relapse after a median of 2 months (range 1-8), and of these, seven had a true positive initial PET with increased uptake of FDG indicating metastatic disease. There were three false negative and no false positive PET scans. The sensitivity, specificity and accuracy of PET were 70%, 100% and 93%, respectively. The sensitivity of detecting small retroperitoneal metastases was 88%. The negative and positive predictive values were 92% and 100%, respectively, whereas the negative predictive value of standard staging procedures was 78%. FDG-PET thus seems to be superior to conventional staging (P=0.06) in stage I NSGCT. This non-invasive method may improve the overall management of patients with NSGCT.

Status of lymph node staging

Sentinel node biopsy has the potential to provide more accurate staging information than axillary node dissection. Given the considerable morbidity of axillary node dissection this less invasive approach is attractive. However, there are a number of issues to be resolved before the best technique of sentinel node biopsy is determined. When large studies with long-term follow up demonstrate that lymphatic mapping to identify clinically occult lymph node metastases is as effective as we hope, then full axillary node dissection can be reserved to treat patients who indeed have lymph node metastases. Around 60% of the patients could then be spared an axillary node dissection that they do not need because they do not have metastases there. Modern technology is providing more accurate prognostic information based on primary tumor characteristics. Applying these technologies to sentinel lymph nodes may render the lymph node status even more relevant than it currently is.

The usefulness of fluorine 18-labelled deoxyglucose positron emission tomography in the investigation of patients with cervical lymphadenopathy from an unknown primary tumor

BACKGROUND

The usefulness of fluorine 18-labelled deoxyglucose positron emission tomography (PET) in the detection of unknown primary tumor in patients seen with malignant cervical lymphadenopathy thought to arise from a head and neck primary differs in the published reports to date. To assess the role of PET in this scenario in our institution, an audit was performed.

METHODS

The records of 21 patients who met the clinical indication were reviewed. End points were the ability of PET to detect an unknown primary tumor and/or distant metastatic disease.

RESULTS

In 8 of the 21 patients, PET detected a potential primary site, although none was unequivocally PET positive. One case was pathologically confirmed. In five patients the potential primary site identified on PET could not be confirmed: two had negative biopsies, and three had no clinical evolution in the PET-suspect area for at least 24 months after the initial study. In the remaining two patients, the potential primary site detected by PET was treated without biopsy. PET detected additional regional and/or distant disease that had not been previously documented in nine cases.

CONCLUSIONS

PET did not add significantly to the detection of an occult primary tumor in patients who had already been comprehensively evaluated by clinical and radiologic investigations. It was of substantial benefit, however, in detecting unsuspected distant disease in patients with undifferentiated nodal histologic findings and helped in delineating regional disease in patients with N2 disease.

Breast cancer imaging with PET and SPECT agents: an in vivo comparison

Several radiopharmaceuticals and imaging techniques are proposed for breast cancer imaging. Since limited data are available of the uptake of SPECT and PET radiopharmaceuticals in malignant breast tumors and their metastases the aim of this study was to compare the uptake values and to correlate these data with imaging findings.

METHODS

We have studied the uptake of F-18 FDG, Tc-99m MIBI and Tc-99m (V)DMSA in 31 tumors using immunosuppressed rats implanted with HH-16 clone 4 mammary tumor cells. Tumor gamma camera and PET imaging was performed to gain biokinetic data and uptake values by ROI-analysis.

RESULTS

Tumor uptake was highest for F-18 FDG > Tc-99m (V)DMSA > Tc-99m MIBI. The uptake ratios (tumor to muscle) correlated well with the ratios calculated by ROI-analysis determined by imaging.

CONCLUSIONS

In this in-vivo model, F-18 FDG revealed the best uptake and imaging properties and may be the radiopharmaceutical of choice for routine breast cancer imaging.

Usefulness of FDG-positron emission tomography in diagnosing peritoneal recurrence of colorectal cancer

BACKGROUND

Accurate detection of peritoneal recurrence in colorectal cancer remains a diagnostic challenge. We retrospectively examined sensitivity and accuracy of fluorine-18-2-fluoro-deoxy-D-glucose positron emission tomography (FDG-PET) in the diagnosis of peritoneal recurrence.

METHODS

FDG-PET and computed tomography (CT) were performed on 23 patients with colorectal cancer suspected of having a recurrence based on clinical symptoms, a tumor marker (CEA), and so forth. The final diagnosis was compared with the results of FDG-PET and CT.

RESULTS

Peritoneal recurrence was suspected in 6 patients with FDG-PET, and 5 of them were finally diagnosed as recurrences. The sensitivity of FDG-PET was 88% and its diagnostic accuracy was 78%, whereas those of CT were 38% and 44%, respectively. A lesion as small as 15 mm in diameter was diagnosed by FDG-PET.

CONCLUSIONS

FDG-PET is an effective method for diagnosing peritoneal recurrence of colorectal cancer. FDG-PET is expected to become more important for detecting peritoneal recurrence at an early stage.

Evaluation of 2-deoxy-D-glucose as a chemotherapeutic agent: mechanism of cell death

Nutrient deprivation has been shown to cause cancer cell death. To exploit nutrient deprivation as anti-cancer therapy, we investigated the effects of the anti-metabolite 2-deoxy-D-glucose on breast cancer cells in vitro. This compound has been shown to inhibit glucose metabolism. Treatment of human breast cancer cell lines with 2-deoxy-D-glucose results in cessation of cell growth in a dose dependent manner. Cell viability as measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide conversion assay and clonogenic survival are decreased with 2-deoxy-D-glucose treatment indicating that 2-deoxy-D-glucose causes breast cancer cell death. The cell death induced by 2-deoxy-D-glucose was found to be due to apoptosis as demonstrated by induction of caspase 3 activity and cleavage of poly (ADP-ribose) polymerase. Breast cancer cells treated with 2-deoxy-D-glucose express higher levels of Glut1 transporter protein as measured by Western blot analysis and have increased glucose uptake compared to non-treated breast cancer cells. From these results we conclude that 2-deoxy-D-glucose treatment causes death in human breast cancer cell lines by the activation of the apoptotic pathway. Our data suggest that breast cancer cells treated with 2-deoxy-D-glucose accelerate their own demise by initially expressing high levels of glucose transporter protein, which allows increased uptake of 2-deoxy-D-glucose, and subsequent induction of cell death. These data support the targeting of glucose metabolism as a site for chemotherapeutic intervention by agents such as 2-deoxy-D-glucose.

Fluorine-18 FDG-PET in detecting local recurrence and distant metastases in breast cancer--Taiwanese experiences

Fluorine-18 fluorodeonyglucose positron emission tomography (FDG-PET) was used to detect local recurrence, axillary lymph node (LN) involvement and distant metastases in patients with breast cancer. Thirty-six female patients with breast cancer s/p operation underwent FDG-PET studies. Findings were confirmed by histology following surgery and/or biopsy or negative follow-up results over a period of at least one year. In the evaluation of local recurrence, the diagnostic sensitivity, specificity, and accuracy of FDG-PET was 100, 96.8, and 97.2%, respectively. In the evaluation of axillary LN involvement, sensitivity, specificity, and accuracy was 80, 100, and 97.2%, respectively. In the evaluation of distant metastases, the diagnostic sensitivity, specificity, and accuracy was 83.3, 85.2, and 84.4%, respectively. The FDG-PET is a useful diagnostic tool in detecting local recurrence, axillary LN involvement, and distant metastasis.

Nuclear medicine in primary breast cancer imaging

The application of nuclear medicine techniques to study patients with breast cancer has recently raised its profile, particularly in the investigation 'indeterminate mammographic lesions'. This review briefly points out some of the difficulties encountered with other more conventional imaging modalities and describes the radionuclide techniques most frequently employed in the investigation of those patients with breast cancer. Both planar and single photon emission tomography methods are discussed including the use of monoclonal antibodies, perfusion ligands, receptor binding hormones and other specific radiotracers, non-specific tumour markers, as well as deoxyglucose and other amino acids labelled with positron emitting radionuclides.

Positron emission tomography for the diagnosis of breast cancer

This article reviews the literature on breast imaging with [18F]fluorodeoxyglucose positron emission tomography (FDG PET). In clinical applications, there is currently no defined role for detecting primary breast cancer. The limited sensitivity of FDG PET does not allow the exclusion of malignancy, in particular small breast carcinomas, micrometastases and small, tumour infiltrated lymph nodes. However, in advanced stages, PET accurately determines the extent of disease, including the loco-regional lymph node status. Furthermore, whole-body PET imaging promises a high diagnostic accuracy for detecting recurrent or metastatic breast carcinoma. Future clinical applications may include monitoring therapeutic effects.

Positron emission tomography in urologic oncology

BACKGROUND

Positron emission tomography (PET) is an emerging imaging modality that is being investigated for use in urologic oncology. PET scanning using the radioactive glucose analog FDG has proven to be a highly accurate imaging test for diagnosing and staging a variety of non-urologic cancer types. This review was performed to determine the role of PET imaging in genitourinary malignancies.

METHODS

A review of the literature focusing on PET and urologic oncology was performed. The role of PET imaging was reviewed in prostate, bladder, renal, and testicular cancer.

RESULTS

In testicular cancer, PET has a higher diagnostic accuracy than computed tomography (CT) for both staging and re-staging and should be the test of choice for the assessment of a CT-visualized residual mass following chemotherapy. In prostate, renal, and bladder cancer, the current role of PET is still being defined, but it has a high positive predictive value and can be used for problem solving in patients with indeterminate findings on conventional imaging. Its role in the diagnosis and staging of prostate cancer is hampered by the generally low glycolytic rate of most prostate tumors and their metastases. It has shown promise for staging and re-staging patients with advanced-stage disease and aggressive tumors suspected by a high tumor grade and high prostate-specific antigen velocity. PET has also demonstrated success when applied to renal cell carcinoma in classifying indeterminate renal masses as well as residual renal fossa masses following nephrectomy, gauging response to therapy, and staging and re-staging patients with a known diagnosis of renal cell carcinoma.

CONCLUSIONS

PET imaging has demonstrated great potential in certain applications, but further investigations are necessary to determine its eventual place as an imaging modality in genitourinary malignancies.

Fluorodeoxyglucose uptake and glucose transporter expression in experimental inflammatory lesions and malignant tumours: effects of insulin and glucose loading

The expression of glucose transporters (GLUTs) and its relationship to fluorodeoxyglucose accumulation in malignant tumours have been well investigated, while such a relation has not been studied in inflammatory lesions. The aim of the present study was to investigate the effects of insulin and glucose loading on the expression of GLUTs in inflammatory lesions and compare them with those in malignant tumours in relation to fluorodeoxyglucose accumulation. All tissue specimens used in this study were obtained in our previous study, in which rats were inoculated with allogenic hepatoma cells (KDH-8), Staphylococcus aureus, or turpentine oil into the left calf muscle and divided into three subgroups: insulin loaded, glucose loaded, and control groups. The expression of glucose transporters (GLUT-1 to GLUT-5) was investigated by immunostaining the lesions (n=5-6, for each group). In all control groups, the expression levels of GLUT-1 and GLUT-3 were significantly higher than those of GLUT-2, GLUT-4 and GLUT-5. Insulin loading did not significantly affect the expression levels of GLUT-1 and GLUT-3 in these lesions except for a significant but slight decrease in the GLUT-1 expression level in the inflammatory lesion of non-infectious origin (89% of the control value). Glucose loading significantly decreased the expression level of GLUT-1 in the inflammatory lesion of non-infectious origin (70% of the control value, P<0.01), and that of GLUT-3 in the inflammatory lesion of infectious origin (70% of the control value, P<0.05), while the expression levels of GLUT-1 and GLUT-3 in the tumour were not significantly affected. These results demonstrate the effects of insulin and glucose loading on the expression level of a molecule (GLUT proteins). The decreased GLUT-1 and GLUT-3 expression levels induced by glucose loading may partly explain the impaired FDG uptake observed in our previous study.

New modalities in breast imaging: digital mammography, positron emission tomography, and sestamibi scintimammography

Digital mammography, PET, and sestamibi scintimammography are three new modalities in breast imaging. DM has advantages over film-screen mammography in image storage, retrieval, and processing and may lower the recall rate. Computer-aided detection may increase the sensitivity of mammographic screening without a substantial reduction in specificity. Whereas PET and sestambi scintimammography are not useful in breast cancer screening, PET may play a role in detecting nodal metastases and monitoring treatment response, and sestamibi scintimammography in selected cases may serve as an adjunct to conventional imaging. The cost-effectiveness of these new modalities remains to be evaluated, but all have the potential to significantly advance the diagnosis and management of women with breast cancer.

Positron emission tomography scanning: current and future applications

Whole-body positron emission tomography (PET) imaging with (18)F deoxyglucose (FDG) is a molecular imaging modality that detects metabolic alterations in tumor cells that are common to neoplastic cells. FDG-PET has recently been approved by the Health Care Finance Administration for Medicare reimbursement for diagnosing, staging, and restaging lung cancer, colorectal cancer, lymphoma, melanoma, head and neck cancer, and esophageal cancer. This review discusses the scientific evidence that led to the emergence of PET imaging as an accepted clinical tool in patients with solitary pulmonary nodules, lung cancer, colorectal cancer, melanoma, lymphoma, breast cancer, and other cancers. When possible, we compare the performance of PET to that of anatomical imaging. We discuss future clinical applications of this imaging modality.

Is enteral administration of fluorine-18-fluorodeoxyglucose (F-18 FDG) a palatable alternative to IV injection? Pre-clinical evaluation in normal rodents

To establish effective methods of enteral 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) administration, the efficiency of FDG absorption in the gastrointestinal tracts following enteral administrations was evaluated using the FDG biodistribution in normal rodents, in combination with various fasting conditions and FDG diluents. The blood FDG curve using hypotonic solution showed a rapid increase, while that in iso- and hypertonic groups showed slow rises. Brain FDG uptake had a close positive correlation with blood AUC (area under curve) and an inverse relationship with the stomach contents.

Advances in FDG PET probes in surgical oncology

Whole-body positron emission tomography (WB-PET) has been developed as a sensitive, cost-effective method for imaging malignant disease. WB-PET provides complete body imaging with a single scanning approach for a variety of malignancies. With increasing clinical experience, the indications for its use have broadened. This article reviews current uses of the technology and discusses some potential applications, particularly the utility of a commercially available surgical gamma probe for detecting the gamma particles emitted in the decay process of FDG.

Evaluation of good clinical response to neoadjuvant chemotherapy in primary breast cancer using [18F]-fluorodeoxyglucose positron emission tomography

To determine whether [18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) can predict complete pathological response (pCR) in patients achieving a good clinical response to neoadjuvant chemotherapy for primary breast cancer, 10 patients underwent FDG PET scanning prior to definitive breast surgery. Scan reports were compared with histopathological findings. No abnormal uptake at the primary tumour site was visualised in any patient. 9 of the 10 patients had residual invasive carcinoma at operation, ranging from 2 to 20 mm in maximum dimension. One patient achieved a complete pathological response. Of the 5 patients who underwent axillary surgery, no axillary FDG uptake was seen preoperatively although 3 of the 5 were histologically node-positive. FDG PET did not reliably identify residual disease in this series of good clinical responders to neoadjuvant chemotherapy, and its discriminatory power as a tool to predict complete pathological response therefore appears to be inadequate for clinical use in this setting.

Positron emission tomography imaging in oncology

The applications for FDG-PET imaging are rapidly growing and accepted in the field of oncology. FDG-PET imaging does not replace other imaging modalities, such as CT, but seems to be very helpful in specific situations where CT has known limitations, such as differentiation of benign from malignant indeterminate lesions on CT, differentiation of post-treatment changes versus recurrent tumor, differentiation of benign from malignant lymph nodes, and monitoring therapy. The biggest use of FDG-PET presently is in N and M staging of various body tumors. The addition of FDG-PET in the evaluation of oncologic patients in well-defined algorithms including a combination of imaging studies seems to be cost effective by accurately identifying patients who benefit from invasive procedures and saving unnecessary costly invasive procedures on patients who do not benefit from them. Although PET imaging may decrease the cost of health care by reducing the number of invasive procedures, implementation of clinical PET has been hindered by the high cost of the purchase, operation expenses, and maintenance of PET systems; the need for immediate access to a source of 18F (owing to the 110-minute half-life); and the limited reimbursement for clinical procedures by third-party payers. These combined factors have resulted in the development by manufacturers of hybrid gamma camera systems capable of performing positron imaging. These systems can be used to image conventional radiopharmaceuticals used in general nuclear medicine and positron-emitting radiopharmaceuticals. The performance of these camera-based PET systems has improved markedly over the past few years with the introduction of thicker NaI (T1) crystals, iterative reconstruction algorithms, and attenuation correction. These new developments in medical imaging instrumentation have contributed to the expansion of the number of cyclotrons, and have driven the concept of commercial FDG distribution centers.

The role of nuclear medicine in breast cancer detection: functional breast imaging

Mammography remains the imaging modality of choice in detection of early, nonpalpable breast cancer. Scintimammography using SPECT, however, may prove to be a very useful adjunct to a nondiagnostic or difficult mammogram. Further prospective studies have to be designed so that the specific clinical applications of this technique are more defined. As with any new imaging procedure, special care to obtain high-quality scintimammographic studies and sufficient training of staff to perform and interpret the imaging are necessary.

Whole body PET for the evaluation of bony metastases in patients with breast cancer: comparison with 99Tcm-MDP bone scintigraphy

The purpose of this study was to determine the potential role of positron emission tomography (PET) using 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) for the evaluation of bony metastasis compared with 99Tcm-methylene diphosphonate (99Tcm-MDP) bone scintigraphy in patients with breast cancer. Fifty-one female patients with breast cancer who had PET together with a bone scan within 1 month between September 1994 and March 1997 were included in this study. The median age was 49 years (range 29-79 years). The sensitivity, specificity and accuracy of the bone scan were 77.7%, 80.9% and 80.3%, respectively. On the other hand, for the detection of bone metastases PET had a sensitivity, specificity and accuracy of 77.7%, 97.6% and 94.1%, respectively. In the diagnosis of bony metastasis derived from breast cancer, FDG-PET was statistically superior to bone scintigraphy in its specificity. In conclusion, FDG-PET appears to be a powerful tool not only in the diagnosis of the primary lesion and soft tissue metastasis, but also in the diagnosis of bony metastasis among patients with breast cancer.

Current status of PET in breast cancer imaging, staging, and therapy

The exact roles of PET in the imaging management of patients with known or suspected breast cancer are still in evolution. For assessing primary lesions, it is sometimes possible with PET to detect cancers occult on standard methods. This could be useful in high-risk patient populations, but in dense breasts, background FDG uptake is often higher than in women with fatty breasts, making identification of lesions < 1 cm in size improbable with current technologies. Distinguishing malignant from benign primary breast disease would seem better addressed by biopsy. With a positive predictive value of FDG PET for cancer over 96%, any FDG-avid breast lesion is highly suspicious and merits biopsy. Although PET in theory should be useful for depicting multifocal disease before surgery, the limitations in detecting small lesions in the breast limit the contribution of PET at present. It is most likely that PET will have a greater role in depicting primary breast lesions as dedicated PET imaging devices for the breast evolve. For axillary and internal mammary nodal staging, results with FDG PET are variable. Small nodal metastases < or = 5 mm will be missed by PET, whereas larger ones are more likely to be detected. PET can depict internal mammary nodes, but the accuracy of the method in this setting is not known, nor is there consensus on how identifying internal mammary node metastases will change treatment. Based on the available data, for pT1 breast lesions, PET, if negative, is not an adequate replacement for sentinel node surgery or axillary dissection. Results from the multicenter trial will be of great interest. Clearly PET can stage metastatic disease well. Bone scans with 18F- are exquisitely sensitive for metastases, and FDG is also very good. However, FDG PET can miss some blastic metastases to bone so at present FDG is not capable of excluding the presence of bone metastases. PET seems very well suited to detecting recurrences in soft tissues and the brachial plexus region in particular. The utility of PET in planning the treatment of individual patients appears promising. Although results must be confirmed in larger studies, it appears safe to conclude that failure of a chemotherapy regimen to decrease FDG uptake promptly in a breast cancer portends poor response. This does not hold true for hormonal therapy. At present, labeled estrogens are not widely available and cannot be recommended for clinical use. Thus, PET has shown considerable promise in breast cancer imaging, but in the author's experience is best applied to solve difficult imaging questions in specific patients and is not recommended for routine evaluation of the breast cancer patient. However, in larger primary tumors, the ability to use PET for staging and to plan treatment response suggest it will be more widely used. Additional studies with newer PET imaging devices and FDG and other tracers will help us better determine the role of PET in routine clinical care of the patient with known or suspected breast cancer. Certainly, this represent a fertile area for translational research studies over the next several years with the potential to significantly alter the way breast cancer is imaged and managed.

Fluorodeoxyglucose positron emission tomography for detection of recurrent or metastatic breast cancer

Fluorodeoxyglucose-positron emission tomography (FDG-PET) is a noninvasive imaging technique capable of identifying primary tumors and metastases with high sensitivity and accuracy. The aim of this study was to evaluate the diagnostic accuracy of whole-body FDG-PET imaging for the detection of recurrent or metastatic breast cancer after surgery. Whole-body FDG-PET imaging was performed on 27 patients with suspected recurrent breast carcinoma. PET images were evaluated qualitatively for each patient and lesion. FDG-PET scans showed that there were 61 reference sites of malignant or benign lesions in 27 patients. In a patient-based analysis, FDG-PET scans correctly identified 16 of 17 patients with recurrent or metastatic disease and 8 of 10 without recurrence, resulting in a sensitivity, specificity, and accuracy of 94%, 80%, and 89%, respectively. In a lesion-based analysis, FDG-PET scans correctly identified 46 of 48 lesion sites with recurrent or metastatic disease and 11 of 13 without recurrence. The overall sensitivity, specificity, and accuracy for all lesion sites were 96%, 85%, and 93%, respectively. FDG-PET scans revealed unsuspected recurrent or metastatic diseases in 8 of 27 (30%) of patients and 11 of 20 (55%) distant metastatic lesions. In 13 patients treatment was altered by the outcome of the PET scan. We concluded that whole-body FDG-PET scan is a useful diagnostic imaging modality for detecting recurrent or metastatic breast carcinoma in patients suspected of having recurrent disease after primary surgery.

Lymph node metastasis from breast cancer diagnosed by F-18 FDG whole-body PET (case report)

We report a 48-year-old woman with lymph node (LN) metastases from breast cancer in whom diagnosis was difficult by conventional imaging methods but easy by F-18 fluorodeoxyglucose (FDG) PET. She was given a diagnosis of right breast cancer and then underwent modified radical mastectomy in December 1997. During routine CT and US studies in September 1998, a questionable LN measuring 1 cm in diameter was detected in the right supraclavicular region, but a definitive diagnosis of this LN was difficult by these tests. The patient underwent FDG PET test, which showed strong nodular activity (SUV= 7.1) in the right supraclavicular region, indicating a metastatic lesion. Moreover, an unexpected second metastatic LN lesion (SUV= 5.5) in the medial aspect of the right axillary was diagnosed by PET. The PET results were confirmed by pathological examination of the surgical specimens. FDG PET is a useful tool to detect small malignant lesions that are not easily diagnosed by conventional imaging techniques such as CT and US. It is expected that PET test will be feasible at many institutions.

Using positron emission tomography with [(18)F]FDG to predict tumor behavior in experimental colorectal cancer

This study investigates the relationship between FDG uptake as determined by positron emission tomography (PET) imaging and rates of tumor growth, cellular GLUT1 transporter density, and the activities of hexokinase and glucose-6-phosphatase in a solid tumor implant model. Five different human colorectal xenografts of different growth properties were implanted in athymic rats and evaluated by dynamic (18)F-FDG-PET. The phosphorylating and dephosphorylating activities of the key glycolytic enzymes, hexokinase and glucose-6-phosphatase, were measured in these tumor types by spectrophotometric assays and the expression of GLUT1 glucose transporter protein was determined by immunohistochemistry. Correlations among FDG accumulation, hexokinase activity, and tumor doubling time are reported in these colon xenografts. The results indicate that the activity of tumor hexokinase may be a marker of tumor growth rate that can be determined by (18)F-FDG-PET imaging. PET scanning may not only be a useful tool for staging patients for extent of disease, but may provide important prognostic information concerning the proliferative rates of malignancies.

Axillary lymph node staging in breast cancer by 2-fluoro-2-deoxy-D-glucose-positron emission tomography: clinical evaluation and alternative management

BACKGROUND

Surgical removal of axillary lymph node and histologic examination for metastases are used to determine whether adjuvant treatment is necessary for patients with breast cancer. Axillary lymph node dissection (ALND) is a costly procedure associated with various side effects, and 80% or more of patients with tumors of 20 mm or less are lymph node negative and might avoid ALND. In this study, we evaluated whether an alternative, noninvasive method--i.e., positron emission tomography (PET) with 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG)-- could be used to determine axillary lymph node status in patients with breast cancer.

METHODS

One hundred sixty-seven consecutive patients with breast cancers of 50 mm or less (range = 5-50 mm; mean = 21 mm) scheduled for complete ALND were studied preoperatively with FDG-PET, and then PET and pathology results from ALND were compared. All statistical tests were two-sided.

RESULTS

The overall sensitivity, specificity, and accuracy of lymph node staging with PET were 94.4% (PET detected 68 of 72 patients with axillary involvement; 95% confidence interval [CI] = 86.0% to 98.2%), 86.3% (82 of 95 patients without axillary involvement; 95% CI = 77.8% to 91.9%), and 89.8% (150 of 167 patients with breast cancer; 95% CI = 84.2% to 93.6%), respectively. Positive- and negative-predictive values were 84.0% (68 patients with histologically positive lymph nodes of 81 patients with positive FDG-PET scan; 95% CI = 74.2% to 90.5%) and 95.3% (82 patients with histologically negative lymph nodes of 86 patients with negative FDG-PET scan; 95% CI = 88.2% to 98.5%), respectively. When PET results for axillary metastasis were analyzed by tumor size, the diagnostic accuracy was similar for all groups (86.0%-94.2%), with higher sensitivity for tumors of 21-50 mm (98.0%) and higher specificity for tumors of 10 mm or less (87.8%), and the range was 93.5%-97.3% for negative-predictive values and 54.5%-94.1% for positive-predictive values. Among the 72 patients with axillary involvement, PET detected three or fewer metastatic lymph nodes in 27 (37.5%) patients, about 80% of whom had no clinically palpable axillary lymph nodes.

CONCLUSIONS

Noninvasive FDG-PET appears to be an accurate technique to predict axillary status in patients with breast cancer and thus to identify patients who might avoid ALND. These results should be confirmed in large multicenter studies.

Application of an [(18)F]fluorodeoxyglucose-sensitive probe for the intraoperative detection of malignancy

BACKGROUND

Whole-body positron emission tomography (PET) has been shown to be a highly sensitive method for detecting malignancy not imaged by conventional modalities. We have adapted a hand-held gamma-ray-sensitive probe to detect the radiation emission from the [(18)F]fluorodeoxyglucose (FDG) used in PET imaging. This pilot study was devised to examine the feasibility of using a hand-held probe to intraoperatively differentiate normal from tumor-bearing tissue.

MATERIALS AND METHODS

A commercially available gamma probe was adapted to detect the radioactivity released from FDG and examined to determine the in vitro sensitivity for localization of a FDG point source. Eight consecutive patients underwent resection of metastatic colon cancer or melanoma; each received a preoperative injection of 7--10 mCi of FDG. The gamma probe was used to determine radioactive counts per second from tumor and normal tissue, and ratios of tumor to adjacent normal background were calculated.

RESULTS

In vitro studies with a FDG point source demonstrated the probe could identify the source with a 50% reduction in maximum counts 1.7 +/- 0.1 cm from the source (full-width half-maximum measurement). Based on the results of their preoperative PET scans 17 tumors were identified from the 8 patients. Of the 17 tumors assessed the in vivo tumor-to-background ratios varied from 1.16:1 to 4.67:1 for the melanoma patients (13 tumors) and from 1.19:1 to 7.92:1 for colon cancer patients (4 tumors). Thirteen tumors were resected; four (2 patients) were unresectable.

CONCLUSIONS

This study demonstrates the use of a hand-held gamma-ray-sensitive probe to intraoperatively differentiate the radioactivity released from FDG from tumor-bearing and adjacent normal tissue. While further studies are necessary for us to optimize the use of this probe, the intraoperative detection of FDG-avid malignancies may ultimately improve our ability to completely resect patients with metastatic disease.

The role of positron emission tomography in skeletal disease

The role of positron emission tomography (PET) in the evaluation and management of skeletal disorders is increasing. A number of reports are available in both benign and malignant disease with a variety of tracers. The bone agent 18F-fluoride can be used to evaluate bone metastases both qualitatively and, for a number of focal and systemic skeletal disorders, quantitatively. 18-Fluorodeoxyglucose is used as a tumor agent in both primary and metastatic bone and bone marrow malignancies; its use has also been described in the evaluation of infection within the skeleton. A possible role for the use of the hypoxia selective tracer 18F-fluoromisonidazole in skeletal infection also exists. This article summarizes the current role of PET in the skeleton with regard to these tracers and diseases.

Delayed (18)F-fluoro-2-deoxy-D-glucose positron emission tomography scan for differentiation between malignant and benign lesions in the pancreas

BACKGROUND

Positron emission tomography (PET) using (18)F-fluoro-2-deoxy-D-glucose (FDG) has been used for the evaluation of various tumors, but accumulation in inflammatory lesions makes it a controversial modality. The aim of this study was to investigate the usefulness of delayed scanning in differentiation between malignant and benign lesions in the pancreas.

METHODS

Forty-seven patients with suspected pancreatic carcinoma were studied by FDG-PET. All patients received approximately 370 megabequerels of FDG after a transmission scan, and an emission scan was performed 1 hour and 2 hours later for all patients. A subset of 19 patients was also scanned at 3 hours postinjection. The standardized uptake value (SUV) was determined, and the retention index was calculated by dividing the increase in the SUV between 1 hour and 2 hours postinjection by the SUV at 1 hour postinjection.

RESULTS

Of 27 malignant lesions, the SUVs of 22 lesions increased at 2 hours postinjection, whereas the FDG uptake in 17 of 20 benign lesions decreased. The SUVs at 3 hours postinjection were higher than those at 2 hours postinjection in 9 of 14 malignant lesions and in 2 of 5 benign lesions. Malignant lesions showed a higher retention index than benign lesions (mean +/- standard deviation: 12. 36 +/- 13.37 and -7.05 +/- 17.28, respectively; P < 0.0001). Applying an SUV of 2.5 at 1 hour postinjection with the cut-off value for the differentiation between malignant and benign lesions caused one false negative result and seven false positive results, with a diagnostic accuracy of 83.0% (39 of 47 patients). However, combining the retention index with the SUV obtained at 2 hours postinjection provided a higher diagnostic accuracy (91.5%; 43 or 47 patients) than the SUV alone. The false negative rate remained constant when the retention index was taken into account. Images at 3 hours postinjection usually were unhelpful in differentiating further between malignant lesions and benign lesions.

CONCLUSIONS

The current data suggest that delayed FDG-PET scanning at 2 hours postinjection may contribute to differentiation between malignant and benign lesions in the pancreas.

N-(n-Benzylpiperidin-4-yl)-2-[18F]fluorobenzamide: a potential ligand for PET imaging of breast cancer

N-(N-Benzylpiperidin-4-yl)-2-[(18)F]fluorobenzamide (2), a potential ligand for PET imaging of sigma receptor, has been found to be a potential agent for detection of breast cancer. In vivo studies in severe combined immunodeficient (SCID) mice bearing MDA-MB231 tumors showed that the uptake of compound 2 in these tumors was high (3.8%/g); the ratios of tumor/muscle and tumor/blood were 6.2 and 7.0, respectively, at 1 h postinjection. Pretreatment of SCID mice with haldol increased the uptake of compound 2 in blood, muscle, and other well-perfused organs while decreasing its uptake in tumors. The ratios of tumor/muscle and tumor/blood decreased from 6.2 and 7.0 to 1.3 and 1.1, respectively, at 1 h postinjection. At 2 h postinjection, the ratios of tumor/muscle and tumor/blood decreased from 4.9 and 7.8 to 1.4 and 1.4, respectively. The tumor uptake of compound 2 in SCID mice bearing primary tumor explants from a human breast cancer patient was lower than that in MDA-MB231 tumors (1.66%/g versus 3.78%/g), and the ratios of tumor/muscle and tumor/blood were 3.5 and 3.7, respectively, at 1 h postinjection. These results suggest that compound 2 may be a potential ligand for PET imaging of breast cancer.

Membrane permeability changes induce hyperpolarization in transformed lymphoid cells under high-density culture conditions

BACKGROUND

Membrane potential changes in cells from the human lymphoid B cell line, JY, evoked by increasing cell density in culture were investigated, as data published on other cell types are controversial. An attempt was also made to clear the underlying mechanism.

METHODS

Nonadherent JY cells were isolated from high-density plateau-phase cultures (type A cells), medium-density log-phase cultures (type B cells), and low-density lag-phase cultures (type C cells). They were analyzed for transmembrane potential, intracellular free concentration of potassium and sodium, membrane permeability for monovalent cations, cell cycle distribution by measuring DNA content, and glucose uptake.

RESULTS

C type cells proved to be relatively depolarized (-41 +/- 3 mV) and cells obtained from the highest density cultures hyperpolarized (-60 +/- 3 mV). Intracellular concentrations ([K](i) = 92-97 mM and [Na](i) = 34-35 mM) were almost identical for each type of cell. The sodium/potassium permeability constant ratio in the A and C type of cells was 0.047 and 0.094, respectively. High-density culture conditions resulted in a pronounced G(1)-phase arrest.

CONCLUSIONS

Differences in the membrane potential values induced by high-density culture conditions were maintained by changes in the membrane permeability for the monovalent cations.

Breast imaging with positron emission tomography and fluorine-18 fluorodeoxyglucose: use and limitations

PURPOSE

To evaluate the diagnostic value of positron emission tomography (PET) using fluorine-18 fluorodeoxyglucose (FDG) for the diagnosis of primary breast cancer.

PATIENTS AND METHODS

Preoperatively, 144 patients with masses suggestive of breast cancer underwent PET imaging of the breast. To identify breast cancer by increased metabolic activity, parametric FDG-PET images were analyzed for increased tracer uptake applying conventional image reading (CIR) and sensitive image reading (SIR). One hundred eighty-five breast tumors were evaluated by histology, revealing 132 breast carcinomas and 53 benign masses.

RESULTS

Breast carcinomas were identified with an overall sensitivity of 64.4% (CIR) and 80.3% (SIR). The increase in sensitivity (SIR) resulted in a noticeable decrease in specificity, from 94.3% (CIR) to 75.5% (SIR). At stage pT1, only 30 (68.2%) of 44 breast carcinomas were detected, compared with 57 (91.9%) of 62 at stage pT2. A higher percentage of invasive lobular carcinomas were false-negative (65.2%) compared with invasive ductal carcinomas (23.7%). Nevertheless, positive PET scans provided a high positive-predictive value (96.6%) for breast cancer.

CONCLUSION

Partial volume effects and varying metabolic activity (dependent on tumor type) seem to represent the most significant limitations for the routine diagnostic application of PET. The number of invasive procedures is therefore unlikely to be significantly reduced by PET imaging in patients presenting with abnormal mammography. However, the high positive-predictive value, resulting from the increased metabolic activity of malignant tissue, may be used with carefully selected subsets of patients as well as to determine the extent of disease or to assess therapy response.

Possibility of Differential Diagnosis of Small Polypoid Lesions in the Gallbladder Using FDG-PET

Purpose: We discuss three cases of patients with small polypoid lesions of gallbladder in which we successfully differentiated the malignancy or benignity preoperatively using positron emission tomography (PET) scanning with 18F-labelled deoxyglucose (FDG).Methods and Results: The first case involves a 47-year-old woman who had a 15 x 10 mm polypoid lesion of the gallbladder. FDG-PET was performed and revealed no FDG uptake. The histopathological diagnosis was a cholesterol polyp. The second case is a 56-year-old woman who had a 22 x 8 mm polypoid lesion in the neck of the gallbladder and wall-thickening of the fundus. FDG-PET was performed and no FDG uptake was found. The postoperative diagnosis was pseudo-tumorous sludge in the neck and adenomyomatosis of the fundus. The third case is a 77-year-old man who had a 15 x 15 mm polypoid lesion in the gallbladder. PET revealed a focus of FDG uptake at the site of the gallbladder. The histopathologic diagnosis was adenocarcinoma. Focal FDG uptake was the sole indicator of a malignant tumor of the gallbladder.Conclusions: FDG-PET may become one of the most useful tools for the accurate preoperative diagnosis of gallbladder carcinoma.

2[F]-fluoro-2-deoxy-D-glucose positron emission tomography is a sensitive tool for the detection of occult primary cancer (carcinoma of unknown primary syndrome) with head and neck lymph node manifestation

BACKGROUND

The neck lymph nodes are a common site of metastases from carcinoma of unknown primary (CUP syndrome). 2[(18) F]-fluoro-2-deoxy-D-glucose positron emission tomography (18-FDG-PET) has been shown to be a sensitive tool for detecting primary malignant lesions as well as metastatic spread. We have prospectively investigated the sensitivity of 18-FDG-PET in detecting occult primary carcinomas with manifestation in the head and neck lymph nodes.

METHODS

From May 1994 to July 1998, in 723 patients a cancer of the head and neck was diagnosed at the University of Cologne ENT outpatient clinic. The routinely performed staging procedures were chest radiography; full blood count; cervical and liver ultrasound; endoscopy of the nasopharynx, oropharynx, hypopharynx, larynx, and esophagus; and laboratory analyses. After the staging workup, in 27 of 723 patients (3.7%) CUP syndrome had to be presumed because the primary cancer could not be detected. In these patients 18-FDG-PET was performed, and images were reconstructed with a transmission-emission fusion technique.

RESULTS

In 7 of 27 patients (26%) 18-FDG-PET revealed an unknown primary: in 2 a bronchial carcinoma, in 2 a nasopharyngeal carcinoma, in 1 a squamous cell carcinoma of the parotid gland, in 1 a squamous cell carcinoma of the hypopharynx, and in 1 a carcinoma of the tonsil. In 4 of 7 patients the occult primary tumor was removed surgically. In 8 of 27 patients therapeutic strategy was changed as a result of the 18-FDG-PET findings.

CONCLUSION

18-FDG-PET should be performed in all patients with CUP syndrome after conventional diagnostic workup fails to identify the primary.