Detection of bone metastases in cancer patients by 18F-fluoride and 18F-fluorodeoxyglucose positron emission tomography.

The use of positron emission tomography (PET) in clinical oncology continues to increase and although there is now a large literature on the use of PET with various tracers in a wide variety of cancers, there has previously been relatively little use specifically in the evaluation of skeletal metastases. However, a number of reports on PET in this area of oncology are now becoming available. The potential advantages of PET over conventional nuclear medicine techniques, including improved spatial resolution, absolute quantitation and the acquisition of tomographic studies as a routine, are also of potential benefit in this area. The bone agent, 18F-fluoride and the tumour agent 18F-fluorodeoxyglucose, have been used to evaluate both benign and malignant skeletal disorders qualitatively and quantitatively and the current knowledge with respect to the skeleton in cancer patients is summarised in this article.     

Detection of occult bone metastases of lung cancer with fluorine-18 fluorodeoxyglucose positron emission tomography

Accurate staging of cancer has a critical role in optimal patient management. Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) is superior to CT in the detection of local and distant metastases in patients with non-small cell lung cancer. Although Tc-99 m methylene diphosphonate (MDP) bone scanning is well established in the evaluation of bone metastases, there are conflicting reports on the use of FDG PET in the evaluation of skeletal metastases. We report on a patient with locally advanced lung carcinoma in whom FDG PET accurately identified previously unsuspected widespread asymptomatic bone metastases (bone scan and X-rays negative, confirmed on MRI). Assessment of glucose metabolism with FDG PET might represent a more powerful tool to detect bone metastases in lung cancer compared with conventional bone scans.     

Detection of cranial metastases by F-18 FDG positron emission tomography

Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) scanning has been useful in the management of various cancers. The normal glucose use of gray matter often limits the detection of metastatic lesions to the brain and skull with FDG PET. The authors report two cases of calvarial metastases: one with pheochromocytoma and the other with non-small-cell lung carcinoma. These cases illustrate the crucial role that FDG PET can play when patients are examined for metastases. The important concept of contrast resolution that is achieved with PET imaging is discussed as an advantage that significantly overcomes its limited spatial resolution in detecting small lesions that may not be detected by anatomic imaging techniques with high spatial resolution.     

Evolving role of positron emission tomography in breast cancer imaging

18F-fluorodeoxyglucose positron emission tomography (FDG-PET) has been used for 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 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 and help tailor therapy to individual patient by improving our ability to quantify the therapeutic target, identify drug resistance factors, and measure and predict early response.     

Flare phenomenon in positron emission tomography in a case of breast cancer—a pitfall of positron emission tomography imaging interpretation

We present an unusual case of breast cancer with increased FDG uptake 4 months after chemotherapy. A PET-CT scan displayed results that mimicked multiple lymph node metastases in the right axilla, the mediastinum, and the bilateral pulmonary hilar regions. However, the increased FDG uptake disappeared 17 months later without any additional medical treatment, suggesting the occurrence of flare phenomenon.     

Benign breast lesions detected by positron emission tomography-computed tomography

¹⁸F-fluorodeoxyglucose positron emission computed tomography (FDG PET-CT) is widely used in the initial staging and response evaluation of patients with malignancy. This review describes a spectrum of benign breast findings incidentally detected by FDG PET-CT at staging that may be misinterpreted as malignancy. We describe the pattern of distribution and intensity of FDG uptake in a spectrum of benign breast diseases with their corresponding typical morphological imaging characteristics to help the nuclear medicine physician and/or general radiologist identify benign lesions, avoiding unnecessary breast imaging work-up and biopsies.     

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

Positron emission tomography using ¹⁸F-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.     

Skeletal metastases from breast cancer: uptake of 18F-fluoride measured with positron emission tomography in correlation with CT

Objective. To characterise the uptake of ¹⁸F in skeletal metastases from breast cancer using positron emission tomography (PET) and to relate these findings to the appearance on CT. Patients and design. PET with ¹⁸F and CT were performed in five patients with multiple skeletal metastases from breast cancer. The CT characteristics were analysed in areas with high uptake on the PET study. Dynamic PET imaging of the skeletal kinetics of the ¹⁸F-fluoride ion were included. Results. The areas of abnormal high accumulation of ¹⁸F correlated well with the pathological appearance on CT. Lytic as well as sclerotic lesions had markedly higher uptake than normal bone, with a 5–10 times higher transport rate constant for trapping of the tracer in the metastatic lesions than in normal bone. Conclusion. PET with ¹⁸F-fluoride demonstrates very high uptake in lytic and sclerotic breast cancer metastases.     

Positron emission tomography and bone metastases

The use of 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in the evaluation and management of patients with malignancy continues to increase. However, its role in the identification of bone metastases is far from clear. FDG has the advantage of demonstrating all metastatic sites, and in the skeleton it is assumed that its uptake is directly into tumor cells. It is probable that for breast and lung carcinoma, FDG-PET has similar sensitivity, although poorer specificity, when compared with the isotope bone scan, although there is conflicting evidence, with several articles suggesting that it is less sensitive than conventional imaging in breast cancer. There is convincing evidence that for prostate cancer, FDG-PET is less sensitive than the bone scan and this may be tumor specific. There is very little data relating to lymphoma, but FDG-PET seems to perform better than the bone scan. There is an increasing body of evidence relating to the valuable role of FDG-PET in myeloma, where it is clearly better than the bone scan, presumably because FDG is identifying marrow-based disease at an early stage. There are, however, several other important variables that should be considered. The morphology of the metastasis itself appears to be relevant. At least in breast cancer, different patterns of FDG uptake have been shown in sclerotic, lytic, or lesions with a mixed pattern, Furthermore, the precise localization of a metastasis in the skeleton may be important with regard to the extent of the metabolic response induced. Previous treatment is highly relevant and it has been found that although the majority of untreated bone metastases are positive on PET scans and have a lytic pattern on computed tomography (CT), after treatment, incongruent CT-positive/PET-negative lesions are significantly more prevalent and generally are blastic, which presumably reflects a direct effect of treatment. Finally, the aggressiveness of the tumor itself may be relevant. The most important question, however, is irrespective of whether a lesion is seen on x-ray, CT, or bone scan and irrespective of lytic of blastic morphology: if the FDG-PET study is negative, what is the clinical relevance of that lesion?     

Fluorine-18 deoxyglucose positron emission tomography for the detection of bone metastases in patients with non-small cell lung cancer

Despite advances in morphological imaging, some patients with lung cancer are found to have non resectable disease at surgery or die of recurrence within a year of surgery. At present, metastatic bone involvement is usually assessed using bone scintigraphy, which has a high sensitivity but a poor specificity. We have attempted to evaluate the utility of the fluorine-18 deoxyglucose positron emission tomography (FDG PET) for the detection of bone metastasis. One hundred and ten consecutive patients with histological diagnosis of non-small cell lung cancer (NSCLC) who underwent both FDG PET and bone scintigraphy were selected for this review. In this group, there were 43 patients with metastatic disease (stage IV). Among these, 21 (19% of total group) had one or several bone metastases confirmed by biopsy (n = 8) or radiographic techniques (n = 13). Radionuclide bone scanning correctly identified 54 out of 89 cases without osseous involvement and 19 out of 21 osseous involvements. On the other hand, FDG PET correctly identified the absence of osseous involvement in 87 out of 89 patients and the presence of bone metastasis in 19 out of 21 patients. Thus using PET there were two false-negative and two false-positive cases. PET and bone scanning had, respectively, an accuracy of 96% and 66% in the evaluation of osseous involvement in patients with NSCLC. In conclusion, our data suggest that whole-body FDG PET may be useful in detecting bone metastases in patients with known NSCLC. Received 10 March and in revised form 7 May 1998     

Measurement of absolute bone blood flow by positron emission tomography

A method of measuring bone blood flow has been developed using ¹⁸F sodium fluoride and positron emission tomography. The blood flow levels are in line with those obtained experimentally from microsphere embolisation. This investigative method could be applied to elucidate a number of clinical questions involving bone perfusion.     

Prevalence and patterns of bone metastases detected with positron emission tomography using F-18 FDG

PURPOSE: The aim of this retrospective study was to report the prevalence and imaging characteristics of bone metastases detected with F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) and, when possible, compare these findings with the performance of bone scans in the same patients. METHODS: The reports of 403 patients with histologically proved malignant disease who underwent a PET scan for initial or post-therapeutic staging were reviewed for the presence of possible bone metastases. Based on the final diagnosis confirmed by histopathologic analysis or clinical follow-up, the PET findings of patients with positive bone metastases were evaluated in terms of location, intensity, and patterns. When the PET scan was positive, the PET results were compared with the findings of available bone scans. RESULTS: PET studies suggested the presence of bone metastases in 38 patients (9%). No follow-up data were available for 9 patients, and the remaining 29 were evaluated further. Of these patients, 6 had false-positive findings, whereas bone metastatic involvement was clinically confirmed in 23 patients. The primary malignant findings included lung cancer (n = 9), esophageal cancer (n = 3), lymphoma (n = 2), melanoma (n = 2), thyroid cancer (n = 2), breast cancer (n = 1), colon cancer (n = 1), prostate cancer (n = 1), testicular cancer (n = 1), and nasopharyngeal cancer (n = 1). On PET, 5 patients had a solitary metastatic focus (22%), and the remaining 18 patients had multiple lesions (78%). The vertebrae were the most frequently involved bones (74%), followed by pelvic bones (70%), ribs (65%), upper extremities including the scapula (48%), sternum (43%), and lower extremities (43%). The patterns of abnormal uptake were classified into three groups: focal (15 patients, 65%), diffuse (2 patients, 9%), and a mixed pattern (6 patients, 26%). Most of the lesions showed intense abnormal uptake (18 patients, 78%); 5 patients had both intense and moderate FDG uptake. Thirteen of the 23 patients with confirmed bone metastases also had a bone scan, which revealed positive bone disease in all of these patients. However, PET consistently revealed more metastatic foci than did the bone scan on a lesion basis. CONCLUSIONS: The most frequent pattern of detectable bone metastases with FDG-PET imaging was multiple foci of intense uptake. PET revealed more lesions than did bone scanning, independent of the type of cancer or location of bone involvement, in patients who were accurately diagnosed by FDG-PET imaging.