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

Comparison of fluorine-18 fluorodeoxyglucose positron emission tomography and technetium-99m methoxyisobutylisonitrile scintimammography in the detection of breast tumours

The aim of this study was to compare, in breast cancer patients, the diagnostic accuracy of positron emission tomography (PET) using fluorine-18 fluorodeoxyglucose (FDG) and scintimammography (SMM) using technetium-99m methoxyisobutylisonitrile (MIBI). A total of 20 patients (40 breasts with 22 lesions) were evaluated serially with MIBI and, on the following day, with FDG. For SMM, planar and single-photon emission tomography imaging in the prone position was performed starting at 10 min following the injection of MIBI (740 MBq). For PET, scans were acquired 45-60 min after the injection of FDG (370 MBq) and attentuation correction was performed following transmission scans. Results from SMM and PET were subsequently compared with the histopathology results. True-positive results were obtained in 12/13 primary breast cancers (mean diameter=29 mm, range 8-53 mm) with both FDG and MIBI. False-negative results were obtained in two local recurrences (diameter <9 mm) with both FDG and MIBI. In benign disease, FDG and MIBI did not localize three fibrocystic lesions, two fibroadenomas and one inflammatory lesion (true-negative), but both localized one fibroadenoma (false-positive). Collectively, the results demonstrate a sensitivity of 92%, and a specificity of 86%, for primary breast cancer regardless of whether FDG or MIBI was used. In contrast to MIBI scintigraphy, FDG PET scored the axillae correctly as either positive (metastatic disease) or negative (no axillary disease) in all 12 patients. The tumour/non-tumour ratio for MIBI was 1.97 (range 1.43-3.1). The mean standard uptake value (SUV) for FDG uptake was 2.57 (range 0.3-6.2). The diagnostic accuracy of SMM was equivalent to that of FDG PET for the detection of primary breast cancer. For the detection of in situ lymph node metastases of the axilla, FDG seems to be more sensitive than 99mTc-MIBI.

Likelihood of malignancy in a solitary pulmonary nodule: comparison of Bayesian analysis and results of FDG-PET scan

OBJECTIVE

To compare the probability of cancer in a solitary pulmonary nodule using standard criteria with Bayesian analysis and result of 2-[F-18] fluoro-2-deoxy-D-glucose-positron emission tomographic (FDG-PET) scan.

SETTING

A university hospital and a teaching Veteran Affairs Medical Center.

METHODS

Retrospective analysis of 52 patients who had undergone both CT scan of the chest and a FDG-PET scan for evaluation of a solitary pulmonary nodule. FDG-PET scan was classified as abnormal or normal. Utilizing Bayesian analysis, the probability of cancer using "standard criteria" available in the literature, based on patient's age, history of previous malignancy, smoking history, size and edge of nodule, and presence or absence of calcification were calculated and compared to the probability of cancer based on an abnormal or normal FDG-PET scan. Histologic study of the nodules was the gold standard.

RESULTS

The likelihood ratios for malignancy in a solitary pulmonary nodule with an abnormal FDG-PET scan was 7.11 (95% confidence interval [CI], 6.36 to 7.96), suggesting a high probability for malignancy, and 0.06 (95% CI, 0.05 to 0.07) when the PET scan was normal, suggesting a high probability for benign nodule. FDG-PET scan as a single test alone was more accurate than the standard criteria and standard criteria plus PET scan in correctly classifying nodules as malignant or benign.

CONCLUSION

FDG-PET scan as a single test was a better predictor of malignancy in solitary pulmonary nodules than the standard criteria using Bayesian analysis. FDG-PET scan can be a useful adjunct test in the evaluation of solitary pulmonary nodules.

FDG PET characterization of renal masses: preliminary experience

OBJECTIVE

This study was undertaken to evaluate the potential efficacy of fluorine-18 2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) to detect renal tumours and to characterize indeterminate renal cysts.

SUBJECTS AND METHODS

Twenty-six PET scans were performed in 21 patients (14 PET scans in 10 patients with malignant renal tumours and 12 PET scans in 11 patients with Bosniak type 3 indeterminate renal cysts). Pathological proof was obtained in 18 of 21 patients (10 with solid neoplasms, eight with indeterminate cysts). Imaging was performed 1 h after injection of 5-10 mCi of FDG with IV administration of Lasix (10 mg) 20 mins after injection. Two consecutive 9.7-cm image segments were scanned to cover the entire renal areas.

RESULTS

PET accurately depicted solid neoplasms as areas of increased uptake in nine of 10 patients. Bilateral renal cell carcinomas were missed in one diabetic patient. All but one indeterminate renal cysts were correctly classified as benign (photopenic areas), but an indeterminate cyst with a 4-mm papillary neoplasm was wrongly classified as benign. There were no false positive PET interpretations. The mean tumour-to-kidney ratio was 3.0 for malignant lesions.

CONCLUSION

We conclude that FDG PET scanning shows promise in the evaluation of indeterminate renal cysts. A positive PET scan in the appropriate clinical setting obviates the need for cyst aspiration. A negative PET scan in conjunction with a negative cyst aspiration offers confirmatory evidence of benignity. Our preliminary results are encouraging and further work is ongoing.

PET FDG studies of Wilms tumors

PURPOSE

Wilms tumor is the most common renal neoplasm in children. The diagnosis is usually suggested by anatomic imaging and established by biopsy or resection. The principal roles of functional imaging have been the search for skeletal metastases and evaluation of renal function. We hypothesized that, like many tumors, Wilms tumors could concentrate 18F-FDG and that evaluation of the metabolic activity of these neoplasms might prove clinically useful.

MATERIALS AND METHODS

Three patients with known or suspected Wilms tumors underwent positron emission tomography (PET) with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) scanning (four scans). A patient with a single Wilms tumor was studied once at the time of diagnosis. The two patients with bilateral Wilms tumors were studied during therapy.

RESULTS

Uptake of FDG was present in the Wilms tumor studied at diagnosis, and in one of the tumors in each of the patients with bilateral disease studied during therapy. In all three cases, the results of the PET scans influenced therapeutic decisions.

CONCLUSION

PET FDG scanning may be useful for the management of selected patients with Wilms tumors.

Preliminary assessment of fluorine-18 fluorodeoxyglucose positron emission tomography in patients with bladder cancer

The purpose of this study was to assess the feasibility of imaging of bladder cancer with fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) scanning. We studied 12 patients with histologically proven bladder cancer who had undergone surgical procedures and/or radiotherapy. Retrograde irrigation of the urinary bladder with 1000-3710 ml saline was performed during nine of the studies. Dynamic and static PET images were obtained, and standardized uptake value images were reconstructed. FDG-PET scanning was true-positive in eight patients (66.7%), but false-negative in four (33.3%). Of 20 organs with tumor mass lesions confirmed pathologically or clinically, 16 (80%) were detected by FDG-PET scanning. FDG-PET scanning detected all of 17 distant metastatic lesions and two of three proven regional lymph node metastases. FDG-PET was also capable of differentiating viable recurrent bladder cancer from radiation-induced alterations in two patients. In conclusion, these preliminary data indicate the feasibility of FDG-PET imaging in patients with bladder cancer, although a major remaining pitfall is intense FDG accumulation in the urine.

Does fluorine-18 fluorodeoxyglucose metabolic imaging of tumours benefit oncology?

Fluoro-deoxyglucose (FDG) is a metabolic marker, which follows the same route into cells as that of glucose, and it can be radiolabelled with fluorine-18, 18F-FDG making it suitable for imaging with positron emission tomography (PET). The fact that rapidly proliferating cells such as tumour cells accumulate 18F-FDG more avidly than those with a normal turnover rate has given rise to its potential in oncology. The rationale and previous published uses of 18F-FDG in oncology are reviewed, together with the various analysis techniques and associated methodological difficulties.

Performance study of a miniature gamma ray scintillation vivo probe for tumor localization

We have developed a miniature gamma-ray endoscopic probe consisting of dual BGO detector probes for tumor detection inside the body cavities. The dual detector system was coupled with random coincidence to decrease the distant background radiation and to improve its spatial resolution for tumor localization.

METHOD

The performance of the probe was investigated with a point source and a water phantom. A solution of positron emitting 18F isotope was used as the source. Clinical trials of the probe were done to localize tumors on the skin surface of four subjects carrying tumors close to the body surfaces, into whom 67Ga-citrate and 18F-FDG radiopharmaceuticals were injected.

RESULTS

Measurements indicated that the spatial resolution of the dual detector probes is around 1.5 times better than the single detector probe, and both single and dual detector endoscopic probe systems are capable of localizing a tumor on a large photon background.

CONCLUSION

The endoscopic probe may be easier to insert inside body cavities due to the small crystal size and the flexible light guides. A single detector probe with higher sensitivity may be useful in searching for tumors over a wide intracavity area but a dual detector probe can be used for precise tumor localization. The detector probe may also be suitable for intraoperative observation.

PET in oncology: will it replace the other modalities?

Medical imaging technology is rapidly expanding and the role of each modality is being redefined constantly. PET has been around since the early sixties and gained clinical acceptance in oncology only after an extreme number of scientific publications. Although PET has the unique ability to image biochemical processes in vivo, this ability is not fully used as a clinical imaging tool. In this overview, the role of PET in relation to other tumor imaging modalities will be discussed and the reported results in the literature will be reviewed. In predicting the future of PET, technical improvements of other imaging modalities need to be dealt with. The fundamental physical principles for image formation with computed tomography (CT), ultrasound (US), magnetic resonance imaging (MRI), photon-emission tomography (PET), and single photon emission CT (SPECT) will not change. The potential variety of radiopharmaceuticals which may be developed is unlimited, however, and this provides nuclear imaging techniques with a significant advantage and adaptive features for future biologic imaging. The current applications of PET in oncology have been in characterizing tumor lesions, differentiating recurrent disease from treatment effects, staging tumors, evaluating the extent of disease, and monitoring therapy. The future developments in medicine may use the unique capabilities of PET not only in diagnostic imaging but also in molecular medicine and genetics. The articles discussed in this review were selected from a literature search covering the last 3 years, and in which comparisons of PET with conventional imaging were addressed specifically. PET studies with the glucose analogue fluorine-18-labeled deoxyglucose (FDG) have shown the ability of detecting tumor foci in a variety of histological neoplasms such as thyroid cancer, breast cancer, lymphoma, lung cancer, head and neck carcinoma, colorectal cancer, ovarian carcinoma, and musculoskeletal tumors. Also, the contribution of the whole body PET (WBPET) imaging technique in diagnosis will be discussed. In the current health care environment, a successful imaging technology must not only change medical management but also demonstrate that those changes improve patient outcome.

Initial assessment of positron emission tomography for detection of nonpalpable regional lymphatic metastases in melanoma

BACKGROUND

The purpose of this pilot study is to determine the feasibility of positron emission tomography with fluorodeoxyglucose (FDG-PET) for detection of nonpalpable regional lymph node metastases in patients with melanoma.

METHODS

Adult patients with histologically proven cutaneous melanoma planned to undergo surgical lymphadenectomy for treatment of nonpalpable subclinical or residual metastatic melanoma in regional lymph node basin(s) participated. Each patient underwent attenuation-corrected PET imaging of the regional lymph node basin(s) with F18 fluorodeoxyglucose (FDG) followed by complete surgical lymphadenectomy. FDG-PET scans were interpreted prospectively by an experienced nuclear medicine physician. FDG-PET scan interpretations and histologic results were then correlated.

RESULTS

Eleven patients underwent 12 FDG-PET scans followed by 12 operations to clear 14 regional lymph node basins. FDG-PET correctly predicted the presence of metastatic melanoma in seven of seven surgical specimens. FDG-PET scans correctly predicted the absence of disease in seven of seven histologically negative node basins. Sensitivity was 1.0; specificity was 1.0.

CONCLUSIONS

This study suggests that increased fluorodeoxyglucose uptake in palpably unremarkable regional lymph node basins in patients with melanoma is highly suggestive of metastatic disease.

Overview by an oncologist: what are the imaging needs of the oncologist and oncological surgeon?

Imaging techniques play an important role in the management of the care of the patient who has suspected or known malignancy. Currently available tests have high sensitivity, but low specificity and high false-positive rates. For example, computed tomography scanning and magnetic resonance imaging provide sensitive cross sectional imaging and have improved the detection of small lesions without increasing etiologic specificity. Many masses cannot be further characterized with current imaging studies which may be a particular problem in the assessment of residual disease versus fibrosis. Often, results of these imaging studies create new problems and confusion that require additional tests and sometimes invasive approaches in order to obtain definite answers. Clearly, the oncologist and oncological surgeon need new screening tests with increased specificity without losing sensitivity for most common cancers, and new imaging techniques for staging and follow-up of very small volume tumors without sacrificing specificity. New nuclear medicine techniques such as positron emission tomography (PET) scan or immunoscintigraphy may provide a functional evaluation of a tumor for screening, staging, and follow-up. Initial results of immunoscintigraphy and PET imaging are very encouraging. They may in the future provide prognostic evaluation addition to anatomical assessment of tumor. Additionally, these new imaging studies survey the entire body and detect metastases at multiple sites (regional and distal) simultaneously. Therefore, we should determine the role of these imaging techniques in carefully controlled prospective trials.

The role of (99m)Tc methoxyisobutylisonitrile in imaging breast cancer

Multiple imaging modalities have been used in evaluating patients suspected of breast cancer. Mammography and ultrasound are the dominant modalities now used by most mammographers. Mammography has been shown to be inaccurate in patients with dense breast or in breasts where significant architectural distortion has occurred. Alternative modalities independent of breast density are currently being evaluated. These include ultrasonography, magnetic resonance imaging, and nuclear medicine techniques. Recent reports indicate methoxyisobutylisonitrile (MIBI) to be promising in the evaluation of patients with difficult to evaluate mammograms. The current sensitivity and specificity figures for MIBI scintigraphy of the breast are dependent on a number of factors. A recent multicenter trial involving 673 patients sponsored by the DuPont-Merck Radiopharmaceutical Corporation indicated an overall sensitivity of 85% with a specificity of 81%. Nonpalpable lesions showed a sensitivity of 55% to 72%. The acceptance of MIBI breast imaging will be dependent on specific applications in which MIBI can be shown to be superior to alternative modalities. A promising subgroup of patients includes patients with dense breasts, breasts with architectural distortions, or extensive scaring from prior biopsies, especially if these patients are considered to be in a high risk category.

Scintigraphic imaging of breast tumors

Technetium-99m-sestamibi scintigraphy has recently emerged as a new procedure for the imaging of malignant breast tumors. A large clinical experience has now been collected and this article reviews the main published results. The major drawback of the procedure appears to be its low sensitivity in detecting lesions smaller than 1 cm. The biological background underlying the tracer accumulation is also described. The stimulating potent applications of this functional imaging technique to non-invasively explore the development, and possibly the reversal, of a multidrug resistance under chemotherapy are discussed. The data related to the use of the positron emitter fluor-18-labeled fluorodeoxyglucose (FDG), a very promising agent for imaging breast as well as other solid tumors, are also reviewed. This situation of specific agents, still under development and such as labeled receptor ligands, is examined.

The 3D and 2D color flow display of breast masses

A prospective study was performed in 24 women with breast masses on mammography going on to surgical biopsy. 2D and 3D power mode and frequency shift color flow Doppler scanning and display were compared. Vessels were displayed as rotatable color volumes in 3D, superimposed on gray-scale slices. The latter were stepped sequentially through the imaged volume. Radiologists rated the masses in each display (3D, 2D and videotapes) on a scale of 1 to 5 (5 = most suspicious) for each of six conventional gray-scale and six new vascular criteria. Thirteen masses proved to be benign and 11 were malignant. 3D provided a stronger subjective appreciation of vascular morphology and allowed somewhat better ultrasound discrimination of malignant masses than did the 2D images or videotapes (specificities of 85%, 79% and 71%, respectively, at a sensitivity of 90%). Only in 3D did the vascularity measures display a trend towards significance in this small study.

Oncological applications of positron emission tomography with fluorine-18 fluorodeoxyglucose

Positron emission tomography (PET) is now primarily used in oncological indication owing to the successful application of fluorine-18 fluorodeoxyglucose (FDG) in an increasing number of clinical indications at different stages of diagnosis, and for staging and follow-up. This review first considers the biological characteristics of FDG and then discusses methodological considerations regarding its use. Clinical indications are considered, and the results achieved in respect of various organs and tumour types are reviewed in depth. The review concludes with a brief consideration of the ways in which clinical PET might be improved.

Use of positron emission tomography to study tumors in vivo

Positron emission tomography (PET) is a non-invasive imaging technique. The ability of PET to visualize biochemistry and physiology in vivo distinguishes this technique from other imaging modalities and renders it of particular interest for oncological studies. PET studies can often differentiate between normal and neoplastic tissue, as well as identify early signs of malignant degeneration through biochemical or physiological changes. Over the past several years, PET studies have been useful in the early diagnosis and the selection of treatment, as well as in following the progression or regression of malignant disease processes. Of particular significance, PET findings can be quantified by using mathematical modeling and computerized data analysis, which makes it possible to produce quantitative images of human pathophysiology in vivo.

Prospective evaluation of fluorine-18 fluorodeoxyclucose positron emission tomography in breast cancer for staging of the axilla related to surgery and immunocytochemistry

The noninvasive staging of axillary lymph nodes for metastases is investigated in patients with breast cancer prior to surgery by positron emission tomography (PET) with fluorine-18-fluoro-2-deoxy-d-glucose (18F-FDG). In 124 patients with newly diagnosed breast cancer, whole-body PET was performed to determine the average differential uptake ratio (DUR) of 18F-FDG in the axillary lymph nodes. Results were correlated with the number of the dissected lymph nodes, size of the primary tumor, tumor type, tumor grade, estrogen and progesterone receptors, DNA ploidy, and the proportion of cells in the synthetic phase of the cell cycle (S-phase). In this prospective study of 124 patients with breast carcinoma, PET correctly categorized all 44 tumor-positive axillary lymph nodes, a sensitivity of 100%. Sixty tumor-negative axillary lymph nodes were negative by PET and 20 tumor-negative axillary lymph nodes were positive by PET. No false-negative PET findings were encountered. A weak correlation was found between DUR and tumor size as well as between DUR and the S-phase of the tumor. In patients with breast carcinoma, 18F-FDG PET can be of value in evaluating axillary lymph nodes for metastatic involvement prior to surgery. It is of particular importance that no false-negative PET findings were encountered, and axillary lymph node dissection might not be necessary in patients without axillary uptake by PET. The DUR of the positive axillary lymph nodes seems to bear a relationship with some of the purported prognostic parameters of the primary tumor.

Fluorine-18 fluoro-2-deoxyglucose positron emission tomography in recurrent rectal cancer: relation to tumour size and cellularity

The aim of this study was to assess the value of fluorine-18 fluoro-2-deoxyglucose (FDG) positron emission tomography in patients with recurrent rectal cancer, in relation to tumour size and cellularity. Thirty-seven patients (21 mean and 16 women; mean age, 55.4+/-9.58 years) with suspected recurrence of rectal cancer were studied. FDG uptake was quantified by the differential absorption ratio (DAR). In 29 patients magnetic resonance imaging was also performed. To evaluate the signal intensity of the lesion, the lesion to muscle signal intensity ratios (SIR) were calculated on T2-weighted images. In seven patients who received surgical treatment the DAR and SIR were compared with the tumour cellularity. All 32 patients with confirmed recurrence showed increased FDG accumulation in the mass (DAR=4.57+/-1.89) in comparison with low FDG accumulation in five patients with scar (DAR=1.17+/-0.43). There was a significant correlation (r=0.661, P<0.001) between the DAR and the tumour diameter. There was no correlation between the DAR and SIR, whereas there was a significant correlation (r=0.565, P<0.01) between the DAR corrected using count recovery coefficient (DAR*) and SIR. In the histopathological findings there was a tendency for the DAR* and SIR to correlate with tumour cellularity. It is concluded that the DAR of recurrent rectal cancer should be evaluated taking into consideration the tumour size and cellularity.

Nuclear medicine techniques in breast imaging

Progress has been made in anatomic imaging with mammography, ultrasound, and MRI, but the noninvasive differentiation of malignant from benign breast masses is an unmet goal. Most breast biopsies still are performed in patients with benign disease. Improved nuclear medicine imaging devices, better radiopharmaceutical agents, and new methods of guiding biopsies and surgery are being developed, signaling a growing role for nuclear medicine techniques. The use of dual-photon positron emission tomography and single-photon imaging are discussed as a means of imaging both primary and regionally metastatic breast cancers.

PET and [18F]-FDG in oncology: a clinical update

Positron emission tomography (PET) has become a very useful adjunct to anatomic imaging techniques, adding unique information to the characterization of disease. The whole-body PET FDG technique developed over the last few years has surpassed most expectations with respect to its utility in clinical oncology. The large spectrum of neoplasms that now can be studied with this approach makes it an essential clinical imaging tool in diagnosis and management for many patients with cancer. The metabolic information provided by this technique is complementary to results from standard clinical and morphological examinations. It may be anticipated that through application of the multi-modality imaging approach, significant advances in medical care will come.

Cost-effectiveness of PET imaging in clinical oncology

To be cost-effective, PET must be diagnostically accurate and effective in improving management without increasing treatment cost. To evaluate diagnostic accuracy, we performed prospective evaluations of whole-body PET imaging in staging of non-small-cell lung cancer (99 patients), detection of recurrent colorectal cancer (57 patients), diagnosis of metastatic melanoma (36 patients), and staging of advanced head and neck cancer (29 patients). In each case, PET was more accurate than anatomic imaging for determination of the presence and extent of tumor and demonstration of nonresectable disease. PET was also more accurate than conventional imaging in staging Hodgkin's disease (30 patients). We evaluated the management impact of PET retrospectively, by reviewing the treatment records of 72 patients with solitary pulmonary nodules or non-small-cell lung cancer, 68 patients with known or suspected recurrent colorectal cancer, 45 patients with known or suspected metastatic melanoma, and 29 patients with advanced head and neck tumors. PET improved patient management by avoiding surgery for nonresectable tumor and for CT abnormalities that proved to be benign by PET imaging. For determining cost impact, the costs of surgical procedures were determined from Medicare reimbursement rates, and the cost of a PET study was taken to be $1800. The savings from contraindicated surgical procedures exceeded the cost of PET imaging by ratios of 2:1 to 4:1, depending on the indication. PET was decisively more accurate and cost-effective than anatomic imaging by CT, combining improved patient care with reduced cost of management.

Detection of bony metastases of androgen-independent prostate cancer by PET-FDG

Fourteen F-18 fluorodeoxyglucose (FDG) studies were carried out in 13 patients known to have bony metastases from carcinoma of the prostate. One patient was newly diagnosed. The remaining patients had various types of therapy and were considered hormonally resistant. The average age was 67. All patients had extensive bony metastases shown on the conventional Tc99m-MDP bone scans. Only about 18% of bony lesions apparent on the conventional bone scans showed corresponding increase of FDG uptake. Anatomical correlation was performed by using co-registered images of SPECT and PET in the same area. The positive FDG uptake was not related to the duration of illness, level of PSA, previous therapy, and magnitude of disease involvement. It appears that only a small percentage of bony metastases is associated with increased glycolysis. It is possible that other metabolic processes are more important than glycolysis for providing prostate cancer with a source of energy and nutrients.

Preliminary results for positron emission mammography: real-time functional breast imaging in a conventional mammography gantry

In order to optimally integrate radiotracer breast imaging within the breast clinic, anatomy and pathology should be easily correlated with functional nuclear medicine breast images. As a first step in the development of a hybrid functional/anatomic breast imaging platform with biopsy capability, a conventional X-ray mammography gantry was modified to image the compressed breast with positron emitters. Phantom studies with the positron emission mammography (PEM) device showed that a 1-cc hot spot could be detected within 5 min. A preliminary clinical trial demonstrated in vivo visualization of primary breast cancer within 4 min. For sites where positron-emitting radionuclides are available, PEM promises to achieve low-cost directed functional examination of breast abnormalities, with the potential for achieving X-ray correlation and image-guided biopsy.

Qualitative [18F]FDG positron emission tomography in primary breast cancer: clinical relevance and practicability

Positron emission tomography (PET) using fluorine-18 2-deoxy-2-fluoro-d-glucose (FDG) is of potential value for the diagnosis of malignant tumours. The aim of this study was to evaluate the use of FDG PET in patients with breast tumours, appraising its applicability in visualising primary carcinomas and regional metastases in a clinical setting. Results of FDG PET were compared with those of mammography, breast ultrasonography and histology in 30 patients with inconclusive breast findings. For PET, transmission and emission images were taken in one or two scan positions, depending on the available time and the clinical status of patients. PET showed focal FDG uptake with high contrast in 21 of 23 primary carcinomas. In one patient, only PET correctly visualized multifocal disease (three foci, O 0.4-1 cm). The accuracy of PET in the detection of primary breast cancer was 90%, and in the detection of involved axillary lymph nodes, 94%. All metastases (lymph nodes, lungs, bones, soft tissues) covered by the field of view and demonstrated by other methods (X-ray, computed tomography, magnetic resonance imaging, bone scan) showed FDG uptake. In three patients, only PET initiated further diagnostic procedures. The results indicate that FDG PET can provide a rapid diagnostic study (45-60 min) and allows accurate tumour staging of several organ systems for primary tumour and metastases with a single imaging study in a routine clinical setting.

Regional 2-[18F]fluoro-2-deoxy-D-glucose uptake varies in normal lung

2-[18F]fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) is a promising imaging procedure for detecting primary and metastatic cancer in the lungs. We have, however, failed to detect some small tumors in the lower lobes of the lungs. This study aimed to determine whether increase 18F background activity in the dependent lower lungs is present, which could make lesion detection more difficult. We measured the standardized uptake values (SUVs) for FDG of normal lung remote from the nodular lesion in 16 patients with newly diagnosed untreated lung lesions strongly suspected to represent non-small cell lung cancers. In addition, 15 patients with known or suspected primary breast cancers without pulmonary lesions were included as control subjects. After PET transmission images of the thorax were obtained, approximately 370 MBq of FDG was injected intravenously and imaging was immediately begun. Patients were supine throughout the study. SUVs were determined with images obtained 50-70 min after FDG injection. Regions of interest (ROIs) of 6x6 pixels were positioned over normal lung in anterior, mid, and posterior portions of upper, middle, and lower lung fields. Thus, as many as 18 ROIs were positioned in each patient. The SUVs of the posterior portion were significantly higher than those of the anterior and mid portions in the population of 31 cases (P <0.001). Also, the mean SUV of the lower lung field was significantly higher than the SUVs of the upper and middle lung fields in this population (P <0.01). This pattern was seen among the two groups of 16 patients suspected of having lung cancer and 15 control subjects. Background 18F activity was highest in posterior and lower lung in these patients. The maximum value of mean SUV observed in normal posterior lower lung was 0.804+/-0.230 (41% greater than the mean SUV in the anterior upper lung), which is in the range of the apparent SUV for a 5-mm lung lesion, with higher SUV, due to recovery coefficient issues. Thus this phenomenon could contribute to occasional false-negative lesions in those areas. Increased blood flow and FDG delivery and also scatter from heart and liver may contribute to the increased lower lung background activity. Regional differences in normal lung FDG uptake are significant and should be considered when interpreting pulmonary PET studies in patients with suspected primary or metastatic lung cancer.

PET imaging of primary mediastinal tumours

Mediastinal masses include a wide variety of tumours and remain an interesting diagnostic challenge for radiologist. We performed positron emission tomography (PET) studies of primary mediastinal tumours in order to predict the malignancy of these tumours preoperatively. Twenty-two patients with primary mediastinal tumours were studied with PET using 2-deoxy-2-[18F]fluoro-D-glucose (FDG). The histological findings of surgical pathology or biopsy, or mediastinoscopy were compared with those of computerised tomography (CT) and PET. PET images were evaluated semiquantitatively using the differential uptake ratio (DUR). Increased FDG uptake was observed in nine of ten patients with malignant tumours, including thymic carcinomas, lymphomas, invasive thymomas and a case of sarcoidosis. A moderate level of FDG uptake was found in a myeloma, non-invasive thymomas, and a schwannoma, whereas a low uptake was observed in a teratoma and various benign cysts. The mean FDG uptake of malignant tumours was significantly higher than that of benign tumours. Both thymic cancer and invasive thymoma showed a high FDG uptake. CT examination resulted in three false-negative and two false-positive cases when used in predicting tumour invasion, while PET was associated with a false-positive and a false-negative case. In conclusion, the use of FDG with PET is clinically helpful in evaluating the malignant nature of primary mediastinal tumours. Our results also suggest that a high FDG uptake reflects the invasiveness of malignant nature of thymic tumours.

Sensitivity and specificity of MR mammography with histopathological correlation in 250 breasts

PURPOSE

The aim of our prospective study was to determine the diagnostic accuracy of MR mammography (MRM) in detecting malignant disease.

MATERIAL AND METHODS

In 231 consecutive patients scheduled for surgery because of mammographic or palpable lesions suspected of malignancy, the breasts were examined with T1-weighted transversal images using a 3-D fast low angle shot (FLASH) sequence. One pre- and 2 post-contrast images were obtained. Histological examination of the surgical specimens showed carcinoma in 155 breasts, of which 138 were invasive and 17 in situ.

RESULTS

MRM detected 144 of the 155 malignancies and was false-negative in 11 cases. Eight of these MRM-missed tumours were invasive and 3 were in situ cancers. Benign lesions were found at microscopy in 95 breasts, of which MRM correctly diagnosed 69. The cellular composition of the 26 false-positive lesions (myxomatous stromal change, high vascularity, and epithelial or apocrine hyperplasia) might explain the false positivity. The sensitivity and specificity of MRM were 93% and 73% respectively.

CONCLUSION

MRM should be interpreted with caution, and supplemented with e.g. mammography and ultrasonography.

Recent developments in breast imaging

A review of breast imaging has already appeared in 1982 in this journal. Consequently, the present article concentrates on a discussion of only those developments of a more recent nature. Although the emphasis is placed on the physical aspects of the different imaging methods concerned, the essential factors relating to the clinical background and the associated radiation risk are also outlined. The completeness of detail depends on the present clinical importance of the method under discussion. X-ray mammography, which is still the most important breast imaging technique and has proved to be an effective method for breast cancer screening, is therefore treated in greater detail. Since the early 1980s, ultrasound B-mode scanning has evolved to an indispensable adjunct to x-ray mammography. For Doppler sonography, diaphanography, contrast-enhanced MRI, CT and DSA, the visualization of a tumour depends essentially on the enhanced vascularity of the lesion. Whether this will prove to be a reliable indicator for malignancy remains to be shown in controlled clinical studies. Common to all imaging systems is the increasing use of digital methods for signal processing, which also offers the possibility of computer-aided diagnosis by texture analysis and pattern recognition.

The use of mammography in breast preservation in locally advanced breast cancer

PURPOSE

As the feasibility of breast preservation in locally advanced breast cancer is currently under evaluation, little information is available correlating mammographic changes to chemotherapy with local outcome. To evaluate the role of mammography in selecting candidates with locally advanced breast cancer for conservative local therapy, we analyzed mammographic changes in the breast to induction chemotherapy and correlated the radiologic appearance with pathologic outcome.

METHODS AND MATERIALS

From 1985 through 1993, 91 patients with Stage III breast cancer were enrolled on a multimodality clinical trial using chemohormonal therapy followed by local treatment and maintenance therapy. Induction therapy consisted of cyclophosphamide, doxorubicin, methotrexate,and 5-fluorouracil with hormonal synchronization using tamoxifen and conjugated estrogens. After nine cycles, surgical biopsies of the breast were performed. Through 1988, clinical examination alone directed the site for postinduction biopsy; for patients treated after 1988, mammography, in addition to physical examination, determined the biopsy location. Local treatment was determined by biopsy result. Patients with a pathologic complete response received radiation only to the breast adn regional nodes, while those with pathologically proven residual disease underwent mastectomy and postoperative radiotherapy. Nine additional cycles of maintenance chemotherapy were administered.

RESULTS

Fifty-five of 91 patients (58%) obtained a clinical complete response (CR) to induction chemotherapy. Twenty-eight of the 53 women with a clinical CR had both pre- and postinduction mammograms. Of these 28 women, 9 obtained a pathologic CR and 19 obtained a pathologic partial response (PR). Fifty-five percent of the pathologic complete responders had resolution of mammographic abnormalities on the postinduction mammograms. Sixty-eight percent (13) of the pathologic partial responders had abnormal mammographic findings. The positive predictive value for residual cancer using physical examination was 92%, while the negative predictive value was only 36%. Among patients with a clinical complete response, the positive and negative predictive values for residual cancer using postinduction mammography were 79% and 56%, respectively. Limitations of mammography included uncertain significance of residual microcalcifications and residual masses on postinduction chemotherapy mammograms.

CONCLUSIONS

Although mammography improved the accuracy of noninvasive evaluations in patients with a clinical complete response, pathologic assessment was still required to determine appropriate local therapy. More sensitive imaging modalities or modifications of film-screen mammography may improve noninvasive detection of residual disease following induction chemotherapy.

Positron emission tomography: 2-deoxy-2-[18F]-fluoro-D-glucose uptake in locally advanced breast cancers

Fifteen patients with locally advanced breast cancers were studied using the radiopharmaceutical 2-deoxy-2-[18F]-fluoro-D-glucose (FDG) with positron emission tomography (PET). Five patients were sequentially imaged before and after two pulses of chemotherapy. In 14 of 15 tumours increased uptake of FDG was observed which correlated with the clinical site of the tumour. The PET images were compared with the mammographic and ultrasonomammographic appearances of the tumours in selected patients. In two patients with normal mammograms PET imaging detected the tumour and in a further four patients, with suspicious but not conclusively malignant mammographic changes, a well-defined area of increased FDG uptake was demonstrated by PET. In all five sequentially imaged tumours, following chemotherapy, there was a decrease of the FDG tumour: normal breast uptake ratio. In four patients who completed a full chemotherapeutic course this change preceded a pathological response of their tumours. These findings suggest that this technique may be of benefit in imaging carcinomas in the breasts of pre-menopausal women which may appear dense on mammography and moreover, that sequential imaging may have a role in the prediction, at an early stage, of the response of locally advanced carcinomas to chemotherapy.

Diagnosis of pancreatic cancer by 2[18F]-fluoro-2-deoxy-D-glucose positron emission tomography

The detection of pancreatic cancer or the discrimination between pancreatic cancer and chronic pancreatitis remains an important diagnostic problem. The increased glucose metabolism in malignant tumours formed the basis for this investigation, which focused on the role of positron emission tomography (PET) with 2[18F]-fluoro-2-deoxy-D-glucose (FDG) in the detection of pancreatic cancer and its differentiation from chronic pancreatitis. Eighty patients admitted for elective pancreatic surgery received preoperatively 250-350 mBq FDG intravenously and emission scans were recorded 45 minutes later. Intense focal activity in the pancreatic region was taken at the time of scanning as showing the presence of pancreatic cancer. The presence of cancer was later confirmed by histological examination of the surgical specimens and histological findings were compared with the preoperative PET results. Forty one patients with pancreatic cancer (group I: n = 42) had a focally increased FDG uptake in the pancreatic region. Two patients with a periampullary carcinoma (group II: n = 6) failed to develop FDG accumulation. In 28 patients with chronic pancreatitis (group III: n = 32) no FDG accumulation occurred. Overall sensitivity and specificity of PET for malignancy (group I + II) were 94% (45 of 48) and 88% (28 of 32), respectively. The standard uptake value of the patients with pancreatic carcinoma was significantly higher than in patients with chronic pancreatitis (3.09 (2.18) v 0.87 (0.56); p < 0.001; median (interquartile range)). These findings show that FDG-PET represents a new and non-invasive diagnostic procedure for the diagnosis of pancreatic cancer and to differentiate pancreatic cancer from chronic pancreatitis. However, the diagnostic potential of this technique requires further evaluation.

Application of whole-body positron emission tomography in the imaging of esophageal cancer: report of a case

We describe herein a case of esophageal cancer in which both primary and metastatic lymph node foci were successfully imaged with whole-body positron emission tomography (PET) scanning. A 75-year-old woman with biopsy-proven squamous cell carcinoma of the esophagus underwent whole-body PET scanning for staging evaluation. The patient was injected with 373.7 MBq [18F]-2-fluoro-2-D-deoxyglucose (FDG), and 60 min later, scanning was performed from the neck to the pelvis. The whole-body images showed intense FDG uptake in the primary lesion and multiple focal areas of increased FDG uptake in the mediastinum and abdomen, which corresponded to the lymph node foci confirmed by computed tomography (CT) scan. To our knowledge, this is the first report of whole-body PET scanning being applied in the imaging of esophageal cancer.

Fluorodeoxyglucose positron emission tomography in pancreatic cancer: an unsolved problem

The aim of this study was to examine the significance and problems of 2-[fluorine-18]-2-deoxy-d-glucose (FDG) positron emission tomography (PET) in diagnosing pancreatic cancer and mass-forming pancreatitis (MFP). PET, X-ray computed tomography (CT) and magnetic resonance (MR) imaging were performed in 15 patients with pancreatic cancer and nine patients with MFP. The areas of the PET scan were determined according to the markers drawn on the patients at CT or MR imaging. Regions of interests (ROIs) were placed by reference to the CT or MR images corresponding to the PET images. Tissue metabolism was evaluated by the differential absorption ratio (DAR) at 50 min after intravenous injection of FDG [DAR = tissue tracer concentration/(injected dose/body weight). The DAR value differed significantly in pancreatic cancer (mean +/- SD, 4.64 +/- 1.94) and MFP (mean +/- SD, 2.84 +/- 2.22) (P < 0.05). In one false-negative case (mucinous adenocarcinoma), the tumour contained a small number of malignant cells. In one false-positive case, lymphocytes accumulated densely in the mass in the pancreatic head. Further studies are necessary to investigate the histopathological characteristics (especially the cellularity) and other factors affecting the FDG DAR on PET images.

PET FDG studies in oncology

Positron emission tomography (PET) studies of cancer with the glucose analog 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) have emerged as both a useful research and clinical method for detecting (diagnosing), staging, and monitoring treatment responses in a variety of neoplasms, including tumors of the brain, head and neck, lung, breast, gastrointestinal and genitourinary systems, lymphatic system, musculoskeletal system, and other organ systems. In addition to FDG, many other positron emitting radiopharmaceuticals are under investigation and development in oncology, but the largest set of clinically relevant results to date has been acquired with FDG. Because most aggressive neoplasms have high glycolytic rates, neoplasms throughout the body may potentially be visualized with PET, using both standard transaxial imaging methods and techniques such as whole body PET imaging for surveying the entire body.

PET imaging of lung tumours and mediastinal lymphoma

Positron emission tomography (PET) of the lung is evaluated regarding its clinical practicability for staging of bronchogenic carcinomas and lymphomas. Stringent quality control, optimized acquisition and reconstruction techniques are of crucial importance. An analysis of 50 PET studies for tumour (T) and lymphnode (N) staging in comparison to CT shows that PET has the highest diagnostic accuracy to classify lesions and is the most promising technique for non-invasive staging. PET cannot be the first imaging modality, but if unnecessary or invasive procedures can be avoided, the additional expense of a PET study seems justified.

Pilot study of positron emission tomography in patients with advanced head and neck cancer receiving radiotherapy and chemotherapy

BACKGROUND

Positron emission tomography (PET) provides a noninvasive modality for evaluating the biochemical processes of normal and pathologic tissue. Preliminary reports of F-18 fluorodeoxyglucose (FDG) PET indicate its potential usefulness in evaluating head and neck tumors. The current study was performed to explore the relationship between changes in tumor FDG metabolism and local control in patients receiving hyperfractionated radiotherapy and concurrent chemotherapy.

METHODS

The study group consisted of six patients with locally advanced, nonmetastatic squamous cell carcinoma of the head and neck. FDG studies were performed prior to, during, and 24 months post-therapy. Ratios of tumor to nontumor FDG uptake in regions of interest (ROI) were compared.

RESULTS

All pretherapy studies demonstrated a focal hypermetabolic abnormality corresponding to the known tumor. The pretherapy tumor to nontumor FDG ratios declined significantly during therapy (p < 0.05) with a similar continued trend post-therapy (p < 0.07).

CONCLUSION

The treatment-induced decrease in tumor hypermetabolism as seen on serial FDG PET parallels the clinical response in squamous carcinoma of the head and neck. Two-year follow-up scans also suggest that continued low tumor to nontumor ratios reflect eradication of local disease. Because of its high cost, a study of larger numbers of patients is necessary to better define the role of PET in the management of head and neck cancer.

FDG-PET for the evaluation of tumor viability after anticancer therapy

To evaluate positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) as an diagnostic tool to determine tumor viability after anticancer therapy, fourteen patients were examined by FDG-PET after the end of the treatment. The lesions with residual viable tumor cells showed higher uptake of FDG than surrounding normal soft tissue. The lesions, in which tumor viability was lost or very low, showed higher uptake of FDG in four cases and similar uptake to normal soft tissue in three cases. The residual increased uptake of FDG was considered to be caused by remaining tumor cells and/or inflammatory reaction to anticancer treatment. FDG-PET after anticancer treatment should be interpreted by considering the reaction due to the treatment and the partial volume artifact of PET caused by the limited spatial resolution.

Synthesis of 2-[18F]fluoro-2-deoxy-L-glucose and positron emission tomography studies in monkeys

2-[18F]Fluoro-2-deoxy-L-glucose was synthesized from its trifluoromethanesulfonyl precursor. The precursor was prepared by selective acetylation and triflation of L-mannose. L-Mannose was first treated with acetic anhydride in the presence of a catalytic amount of perchloric acid and then reacted with phosphorus tribromide followed by aqueous sodium acetate to produce pure 1,3,4,6-tetra-O-acetyl-a-L-mannopyranose in 32% yield. This compound was treated with trifluoromethanesulfonic anhydride and pyridine in methylene chloride to form 1,3,4,6-tetra-O-acetyl-O-tritrifluoromethanesulfonyl-a-L-mannopyra nose in 77% yield. Nucleophilic substitution of the triflate with 18F-in the presence of Kryptofix 2,2,2 followed by acid hydrolysis produced 2-[18F]fluoro-2-deoxy-L-glucose with a radiochemical yield of 20-30% (EOS) within 90 min. Biodistribution studies in rats and PET imaging in Rhesus monkeys demonstrated that this sugar analog distributes in the extracellular space of most organs but is excluded from the CNS.

Review of imaging techniques for the diagnosis of breast cancer: a new role of prone scintimammography using technetium-99m sestamibi

Imaging techniques currently used for the diagnosis of breast cancer are reviewed and compared. Besides mammography, magnetic resonance imaging, positron emission tomography, and thallium-201 scintimammography, a new role of technetium-99m sestamibi scintimammography is discussed. It is concluded that while mammography remains the procedure of choice in screening asymptomatic women for breast cancer, other imaging methods play an important role in detecting malignancies in symptomatic patients. 99mTc-sestamibi scintimammography has high sensitivity and improves the specificity of conventional mammography for the detection of breast cancer; with this technique, prone imaging is preferable to supine imaging. 99mTc-sestamibi scintimammography thus deserves further study as a screening technique.

Positron emission tomography and breast masses: comparison with clinical, mammographic, and pathological findings

BACKGROUND

Positron emission tomography (PET) is a means of imaging tissue based upon its metabolic activity. Initial studies in the field of oncology suggest that PET may be useful for diagnosis, staging, and treatment of various tumors.

METHODS

Twenty-eight patients with 37 breast lesions were studied with PET using [fluorine-18] 2-deoxy-2-fluoro-D-glucose (FDG) to assess which clinicopathological characteristics relate to FDG accumulation by the primary tumor.

RESULTS

PET-FDG was found to successfully discriminate malignant from benign breast lesions (p = 0.02) and identify axillary lymph node metastases. FDG uptake by the primary tumor was found to be independent of age, menopausal status, race, tumor size, laterality, histologic differentiation, ploidy, DNA index, estrogen or progesterone receptor value, pathologic stage, and serum glucose. Higher tumor nuclear grade and S-phase were associated with more FDG accumulation by the primary tumor compared with normal breast tissue. PET-FDG correctly identified five malignant lesions that were indeterminant for cancer both on clinical breast examination and mammography and identified one occult cancer that was neither palpable nor apparent mammographically. PET-FDG correctly identified clinical occult axillary metastatic cancer in five patients.

CONCLUSIONS

This study shows that PET-FDG imaging can distinguish malignant from benign breast lesions among a diverse group of patients and suggests that PET-FDG may not only allow for preoperative staging of patients but also provide information about prognosis. This study provides impetus for continued research into PET-FDG imaging of breast lesions, which could have a major impact on the treatment of breast cancer.

Modern techniques in radiological imaging related to oncology

BACKGROUND

Radiological imaging has existed for about 100 years and there have been significant advances in computer technology during the last 25 years. The ideal investigation should be non-invasive, repeatable, and have a sensitivity (detection of the lesion) and specificity (ability to predict the absence of disease) of 100%.

TECHNIQUES

Recent advances in ultrasonography, computed tomography (CT) scanning and magnetic resonance imaging (MRI) have enabled a more accurate demonstration of anatomical structures and better spatial resolution. This has led to the detection of smaller lesions and faster scan times, and thus new or recurrent disease is demonstrated at an earlier stage and motion artefacts are reduced. Advances in imaging techniques have also enabled percutaneous manoeuvres, ranging from diagnostic biopsy of suspicious lesions to therapeutic stenting of malignant strictures, to be performed. Magnetic resonance spectroscopy (MRS) and positron emission tomography (PET) represent a different concept. They assess in vivo tissue metabolism and provide a physiological approach which allows comparison of normal and abnormal tissue, such as tumour. The measurement of certain metabolites or isotope tracers correlates with tumour metabolism, and the response to treatment can be predicted by quantitative changes. Thus, PET scanning and MRS will probably be valuable in assessing new chemotherapeutic agents in animals and patients in vivo. Patients likely to respond to a certain drug can be selected and further studies may help determine ideal dosing regimens. Lack of fine anatomical detail on PET images can be overcome by 'fusing' the 'slice' with the corresponding CT or MRI slice, allowing accurate anatomical and physiological information to be displayed.

CONCLUSION

As more specific indicators of disease and the response to therapy become available, the combination of anatomical and functional imaging modalities will enable treatment to be undertaken at an earlier stage with the potential for increased survival.

Overexpression of Glut-1 glucose transporter in human breast cancer. An immunohistochemical study

BACKGROUND

Breast cancers have higher than normal glucose metabolism, but the mechanism of glucose entry into these tumors is not well understood.

METHODS

The expression of five facilitative glucose transporters, Glut-1 (erythrocyte type), Glut-2 (liver type), Glut-3 (brain type), Glut-4 (muscle/fat type), and Glut-5 (small intestine type), was studied by immunohistochemistry of paraffin sections from 12 primary human breast cancers and 8 lymph node metastases from 2 patients. Rat tissues known to express these glucose transporters were used as controls.

RESULTS

All the primary breast cancers and the lymph node metastases were positive for Glut-1. This transporter was expressed on the cell membrane and in the cytoplasm of the tumor cells, but exhibited marked intratumoral and intertumoral variability in the proportions of positive cells and the intensity of staining. Staining of the normal mammary epithelium, if present, was much lower than observed in tumor cells from the same patient. Glut-2 was expressed in all of the tumors, but the intensity of staining was not consistently stronger than that seen in healthy breast. Clusters of Glut-4-positive granule were observed in cells in six of the tumors. None of the tumors or the healthy breast in the tissues studied expressed Glut-3 or Glut-5.

CONCLUSIONS

Higher expression of the glucose transporter Glut-1 by breast cancer cells compared with the healthy breast tissue is common. Increased glucose transporter protein expression may contribute to the increased uptake of 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) by these tumors observed by positron emission tomography (PET) imaging.