Measuring response to chemotherapy in locally advanced breast cancer: methodological considerations

Prediction of disease-free survival using relative change in FDG-uptake early during neoadjuvant chemoradiotherapy for potentially curable esophageal cancer: A prospective cohort study

18F-Fluorodeoxyglucose positron emission tomography (FDG-PET) has been investigated as a tool for monitoring response to neoadjuvant chemo- and chemoradiotherapy (CT and CRT, respectively) and as a predictor for survival in patients with esophageal cancer. In contrast to patients who undergo neoadjuvant CT, it is not known whether patients who are clinically identified as responders after neoadjuvant CRT show better disease-free survival (DFS) than patients identified as nonresponders. The aim of the study was to determine the predictive value of FDG-uptake measured prior to and early during neoadjuvant CRT. Patients treated with neoadjuvant CRT between 2004 and 2009 within a randomized trial were included. FDG-uptake was measured at baseline and after 14 days of CRT. According to the PERCIST-criteria, patients were allocated to have metabolic response, stable disease, or progression. Patients were followed until recurrence of disease or death. The predictive value of FDG-PET was determined with univariable and multivariable analysis in patients who underwent potentially curative surgery. One-hundred and six patients were included in the analysis. Minimal follow-up for surviving patients was 60 months. No significant differences in DFS were found between patients with metabolic response, stable disease, or progression, with 5-year DFS rates of 66%, 53%, and 67%, respectively (P = 0.39). Relative change in FDG uptake after 14 days of CRT is not associated with DFS in patients with esophageal cancer undergoing neoadjuvant chemoradiotherapy followed by surgery. These measurements should not be used for prognostication in this specific group of patients.

Effects of flutamide on [methyl-(3)h]-choline uptake in human prostate cancer-3 cells: a pilot study

BACKGROUND

Positron emission tomography using [methyl-(11)C]-choline is effective in imaging many types of cancer, especially prostate cancer (PC). The antiandrogen flutamide is often used as part of the initial treatment of PC. Data on the effect of flutamide on and methylcholine incorporation into PC-3 cells are lacking in the experimental and literature work.

OBJECTIVES

The aims of this study were to assess whether human PC-3 cells are susceptible to flutamide and whether the drug modulates the uptake of [methyl-(3)H]-choline into these cells.

METHODS

PC-3 cells were treated for 3 days with flutamide (≤100 nmol/L), inhibiting growth by 20% to 70% with control cells included. Two viability tests (cytotoxic analyses), the thiazole blue assay and the trypan blue exclusion method, were used to determine the median inhibitory concentration for flutamide (10 nmol/L). Control and flutamide-treated cells were incubated with [methyl-(3)H]-choline for 10 minutes and then in nonradioactive medium for 10 minutes to simulate the rapid blood clearance of [methyl-(11)C]-choline tracer that occurs within 5 to 20 minutes, and then extracted using organic and aqueous solvents to determine the intracellular distribution of the tracer. Protein assay and flow-cytometry analysis were used to determine protein content and DNA synthesis in both control and treated cells. The uptake of [methyl-(3)H]-choline was normalized to protein content and expressed as mean (SD) dpm/1Jg protein (n = 6).

RESULTS

PC-3 cell proliferation was inhibited with flutamide treatment. After treatment of PC-3 cells with flutamide 10 nmol/L for 3 days, cells accumulated DNA during the S phase. Mean (SD) [methyl-(3)H]-choline uptake was found to be significantly lower with flutamide 10-nmol/L-treated cells compared with control cells (65.95 [0.72] vs 114.21 [0.57] dpm/1Jg protein; P < 0.001); the difference between the 5-nmol/L-treated cells and controls was nonsignificant.

CONCLUSIONS

In this pilot study, flutamide inhibited tumor cell growth and proliferation and decreased (modulated) the uptake of [methyl-(3)H]-choline into androgen receptor-negative PC-3 cells. These results suggest that flutamide might inhibit proliferation by an androgen-independent mechanism.

Heterogeneity in lung (18)FDG uptake in pulmonary arterial hypertension: potential of dynamic (18)FDG positron emission tomography with kinetic analysis as a bridging biomarker for pulmonary vascular remodeling targeted treatments

BACKGROUND

Pulmonary arterial hypertension (PAH) is a disease of progressive vascular remodeling, characterized by dysregulated growth of pulmonary vascular cells and inflammation. A prevailing view is that abnormal cellular metabolism, notably aerobic glycolysis that increases glucose demand, underlies the pathogenesis of PAH. Increased lung glucose uptake has been reported in animal models. Few data exist from patients with PAH.

METHODS AND RESULTS

Dynamic positron emission tomography imaging with fluorine-18-labeled 2-fluoro-2-deoxyglucose ((18)FDG) ligand with kinetic analysis demonstrated increased mean lung parenchymal uptake in 20 patients with PAH, 18 with idiopathic PAH (IPAH) (FDG score: 3.27±1.22), and 2 patients with connective tissue disease (5.07 and 7.11) compared with controls (2.02±0.71; P<0.05). Further compartment analysis confirmed increased lung glucose metabolism in IPAH. Lung (18)FDG uptake and metabolism varied within the IPAH population and within the lungs of individual patients, consistent with the recognized heterogeneity of vascular pathology in this disease. The monocrotaline rat PAH model also showed increased lung (18)FDG uptake, which was reduced along with improvements in vascular pathology after treatment with dicholoroacetate and 2 tyrosine kinase inhibitors, imatinib and sunitinib. Hyperproliferative pulmonary vascular fibroblasts isolated from IPAH patients exhibited upregulated glycolytic gene expression, along with increased cellular (18)FDG uptake; both were reduced by dicholoroacetate and imatinib.

CONCLUSIONS

Some patients with IPAH exhibit increased lung (18)FDG uptake. (18)FDG positron emission tomography imaging is a tool to investigate the molecular pathology of PAH and its response to treatment.

Validity of simplified 3'-deoxy-3'-[18F]fluorothymidine uptake measures for monitoring response to chemotherapy in locally advanced breast cancer

Purpose

Positron emission tomography using 3′-deoxy-3′-[¹⁸F]fluorothymidine ([¹⁸F]FLT) has been suggested as a means for monitoring response to chemotherapy. The aim of this study was to evaluate the validity of simplified uptake measures for assessing response to chemotherapy using [¹⁸F]FLT in locally advanced breast cancer (LABC).

Procedures

Fifteen LABC patients underwent dynamic [¹⁸F]FLT scans both prior to and after the first cycle of chemotherapy with fluorouracil, epirubicin or doxorubicin, and cyclophosphamide. The net uptake rate constant of [¹⁸F]FLT, K_i, determined by non-linear regression (NLR) of an irreversible two-tissue compartment model was used as the gold standard. In addition to Patlak graphical analysis, standardised uptake values (SUV) and tumour-to-whole blood ratio (TBR) were used for analysing [¹⁸F]FLT data. Correlations and relationships between simplified uptake measures and NLR before and after chemotherapy were assessed using regression analysis.

Results

No significant differences in both pre- and post-chemotherapy relationships between any of the simplified uptake measures and NLR were found. However, changes in SUV between baseline and post-therapy scans showed a significant negative bias and slope less than one, while TBR did not.

Conclusions

In LABC, TBR instead of SUV may be preferred for monitoring response to chemotherapy with [¹⁸F]FLT.

Molecular pathways and molecular imaging in breast cancer: an update

Breast cancer is a heterogenic cancer being characterized by a variability of somatic mutations and in particular by different receptor expressions, such as estrogen, progesterone and human epidermal receptor. These phenotype characteristics play a crucial role in determining tumour response to various chemotherapies and other treatments and in the development of resistance to therapies. Positron emission tomography (PET) as a nuclear medicine technique, has recently demonstrated the advantages in determining the severity of disease and in evaluating the efficacy of treatments in a variety of neoplasm, including breast cancer. Because this procedure is able to pinpoint molecular activity within the body, it offers the potential to identify disease in its earliest stages as well as a patient's immediate response to therapeutic interventions in a non-invasive way. In this paper we performed an extended view about the correlation between molecular factors of breast cancer and PET tracers; in particular, we focalized our attention on their possible advantages in terms of 1) early detection of primary or recurrent cancer; 2) as a guide for target therapies and 3) for the evaluation of response to specific and now-available molecular treatments.

Promise and pitfalls of quantitative imaging in oncology clinical trials

Quantitative imaging using computed tomography, magnetic resonance imaging and positron emission tomography modalities will play an increasingly important role in the design of oncology trials addressing molecularly targeted, personalized therapies. The advent of molecularly targeted therapies, exemplified by antiangiogenic drugs, creates new complexities in the assessment of response. The Quantitative Imaging Network addresses the need for imaging modalities which can accurately and reproducibly measure not just change in tumor size but changes in relevant metabolic parameters, modulation of relevant signaling pathways, drug delivery to tumor and differentiation of apoptotic cell death from other changes in tumor volume. This article provides an overview of the applications of quantitative imaging to phase 0 through phase 3 oncology trials. We describe the use of a range of quantitative imaging modalities in specific tumor types including malignant gliomas, lung cancer, head and neck cancer, lymphoma, breast cancer, prostate cancer and sarcoma. In the concluding section, we discuss potential constraints on clinical trials using quantitative imaging, including complexity of trial conduct, impact on subject recruitment, incremental costs and institutional barriers. Strategies for overcoming these constraints are presented.

Early metabolic response using FDG PET/CT and molecular phenotypes of breast cancer treated with neoadjuvant chemotherapy

Background

This study was aimed 1) to investigate the predictive value of FDG PET/CT (fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography) for histopathologic response and 2) to explore the results of FDG PET/CT by molecular phenotypes of breast cancer patients who received neoadjuvant chemotherapy.

Methods

Seventy-eight stage II or III breast cancer patients who received neoadjuvant docetaxel/doxorubicin chemotherapy were enrolled in this study. FDG PET/CTs were acquired before chemotherapy and after the first cycle of chemotherapy for evaluating early metabolic response.

Results

The mean pre- and post-chemotherapy standard uptake value (SUV) were 7.5 and 3.9, respectively. The early metabolic response provided by FDG PET/CT after one cycle of neoadjuvant chemotherapy was correlated with the histopathologic response after completion of neoadjuvant chemotherapy (P = 0.002). Sensitivity and negative predictive value were 85.7% and 95.1%, respectively. The estrogen receptor negative phenotype had a higher pre-chemotherapy SUV (8.6 vs. 6.4, P = 0.047) and percent change in SUV (48% vs. 30%, P = 0.038). In triple negative breast cancer (TNBC), the pre-chemotherapy SUV was higher than in non-TNBC (9.8 vs. 6.4, P = 0.008).

Conclusions

The early metabolic response using FDG PET/CT could have a predictive value for the assessment of histopathologic non-response of stage II/III breast cancer treated with neoadjuvant chemotherapy. Our findings suggest that the initial SUV and the decline in SUV differed based on the molecular phenotype.

Trial Registration

ClinicalTrials.gov: NCT01396655

[F]fluoro-2-deoxy-d-glucose incorporation by mcf-7 breast tumour cells in vitro is modulated by treatment with tamoxifen, Doxorubicin, and docetaxel: relationship to chemotherapy-induced changes in ATP content, hexokinase activity, and glucose transport

Breast tumours responding to chemotherapy exhibit decreased [¹⁸F]fluoro-2-deoxy-D-glucose ([¹⁸F]FDG) incorporation. Underlying mechanisms of these changes is poorly understood. Here, in MCF-7 cells, responding to chemotherapy drugs commonly utilised in the treatment of breast cancer, [¹⁸F]FDG incorporation and several pivotal factors associated with [¹⁸F]FDG incorporation investigated. Methods. IC50 and subclinical doxorubicin, docetaxel, and tamoxifen doses determined using MTT assay. [¹⁸F]FDG incorporation by cells treated with IC50 drug doses for 48 hours and 72 hours were determined and FDG dephosphorylation estimated by measuring loss of 18F from [¹⁸F]FDG-preincubated cells (pulse-chase). Glucose transport determined by measuring initial uptake rate of non-metabolised glucose analogue omethylglucose; hexokinase activity and ATP content measured in cell homogenates; Cell cycle distribution determined using flow cytometry of propidium iodide stained nuclei. Results. [¹⁸F]FDG incorporation and ATP content decreased in cells after 72 hours treatment with IC50 doses of tamoxifen, doxorubicin, and docetaxel compared with untreated controls. Decreased glucose transport and/or hexokinase activity accompanied decreased [¹⁸F]FDG incorporation by MCF-7 cells treated with tamoxifen or doxorubicin but not docetaxel. Conclusions. Tumour cell [¹⁸F]FDG incorporation along with ATP content decreased by treatment with tamoxifen, doxorubicin and docetaxel paralleling clinical observations for solid tumours. Effect of each treatment on glucose transport and hexokinase activity was chemotherapy-drug dependent.

Detecting treatment response in a model of human breast adenocarcinoma using hyperpolarised [1-13C]pyruvate and [1,4-13C2]fumarate

BACKGROUND

The recent introduction of a dynamic nuclear polarisation technique has permitted noninvasive imaging of tumour cell metabolism in vivo following intravenous administration of (13)C-labelled cell substrates.

METHODS

Changes in hyperpolarised [1-(13)C]pyruvate and [1,4-(13)C(2)]fumarate metabolism were evaluated in both MDA-MB-231 cells and in implanted MDA-MB-231 tumours following doxorubicin treatment.

RESULTS

Treatment of MDA-MB-231 cells resulted in the induction of apoptosis, which was accompanied by a decrease in hyperpolarised (13)C label flux between [1-(13)C]pyruvate and lactate, which was correlated with a decrease in the cellular NAD(H) coenzyme pool. There was also an increase in the rate of fumarate conversion to malate, which accompanied the onset of cellular necrosis. In vivo, the decrease in (13)C label exchange between pyruvate and lactate and the increased flux between fumarate and malate, following drug treatment, were shown to occur in the absence of any detectable change in tumour size.

CONCLUSION

We show here that the early responses of a human breast adenocarcinoma tumour model to drug treatment can be followed by administration of both hyperpolarised [1-(13)C]pyruvate and [1,4-(13)C(2)]fumarate. These techniques could be used, therefore, in the clinic to detect the early responses of breast tumours to treatment.

Quantitative analysis of PET studies

Quantitative analysis can be included relatively easily in clinical PET-imaging protocols, but in order to obtain meaningful quantitative results one needs to follow a standardized protocol for image acquisition and data analysis. Important factors to consider are the calibration of the PET scanner, the radiotracer uptake time and the approach for definition of regions of interests. Using such standardized acquisition protocols quantitative parameters of tumor metabolism or receptor status can be derived from tracer kinetic analysis and simplified approaches such as calculation of standardized uptake values (SUVs).

Using 18F-fluorodeoxyglucose positron emission tomography to monitor clinical outcomes in patients treated with neoadjuvant chemo-radiotherapy for locally advanced pancreatic cancer

BACKGROUND

Pancreatic cancer ranks as the fourth leading cause of cancer death in the United States with 5-year survival ranging from 1% to 5%. Positron emission tomography (PET) is a metabolic imaging system that is widely used for the initial staging of cancer and detecting residual disease after treatment. There are limited data, however, on the use of this molecular imaging technique to assess early tumor response after treatment in pancreatic cancer.

METHODS

The objective of the study was to explore the relationship of early treatment response using the F-fluorodeoxyglucose (FDG) PET with surgical outcome and overall survival in patients with locally advanced pancreatic cancer. FDG-PET measurements of maximum standardized uptake value and kinetic parameters were compared with the clinical outcome.

RESULTS

Twenty patients were enrolled in the study evaluating neoadjuvant induction chemotherapy followed by concurrent chemoradiotherapy (chemo-RT) for locally advanced pancreatic cancer. All 20 patients had prestudy PET scans and a total of fifty PET scans were performed. Among patients who were PET responders (> or =50% decrease in standardized uptake value after cycle 1), 100% (2/2) had complete surgical resection. Only 6% (1/16) had surgical resection in the PET nonresponders (<50% decrease). Two patients did not have the second PET scan because of clinical progression or treatment toxicity. Mean survival was 23.2 months for PET responders and 11.3 months for nonresponders (P = 0.234). Similar differences in survival were also noted when response was measured using Patlak analysis.

CONCLUSIONS

FDG-PET can aid in monitoring the clinical outcome of patients with locally advanced pancreatic cancer treated with neoadjuvant chemo-RT. FDG-PET may be used to aid patients who could have complete surgical resection as well as prognosticate patients' survival.

The role of chemotherapeutic drugs in the evaluation of breast tumour response to chemotherapy using serial FDG-PET

Introduction

The aims of this study were to investigate whether drug sequence (docetaxel followed by anthracyclines or the drugs in reverse order) affects changes in the maximal standard uptake volume (SUV_max) on [¹⁸F]flourodeoxyglucose positron emission tomography (FDG-PET) during neoadjuvant chemotherapy in women with locally advanced breast cancer.

Methods

Women were randomly assigned to receive either drug sequence, and FDG-PET scans were taken at baseline, after four cycles and after eight cycles of chemotherapy. Tumour response to chemotherapy was evaluated based on histology from a surgical specimen collected upon completion of chemotherapy.

Results

Sixty women were enrolled into the study. Thirty-one received docetaxel followed by anthracyclines (Arm A) and 29 received drugs in the reverse order (Arm B). Most women (83%) had ductal carcinoma and 10 women (17%) had lobular or lobular/ductal carcinoma. All but one tumour were downstaged during therapy. Overall, there was no significant difference in response between the two drug regimens. However, women in Arm B who achieved complete pathological response had mean FDG-PET SUV_max reduction of 87.7% after four cycles, in contrast to those who had no or minor pathological response. These women recorded mean SUV_max reductions of only 27% (P < 0.01). Women in Arm A showed no significant difference in SUV_max response according to pathological response. Sensitivity, specificity, accuracy and positive and negative predictive values were highest in women in Arm B.

Conclusions

Our results show that SUV_max uptake by breast tumours during chemotherapy can be dependent on the drugs used. Care must be taken when interpreting FDG-PET in settings where patients receive varied drug protocols.

Lesion quantification in oncological positron emission tomography: a maximum likelihood partial volume correction strategy

A maximum likelihood (ML) partial volume effect correction (PVEC) strategy for the quantification of uptake and volume of oncological lesions in 18F-FDG positron emission tomography is proposed. The algorithm is based on the application of ML reconstruction on volumetric regional basis functions initially defined on a smooth standard clinical image and iteratively updated in terms of their activity and volume. The volume of interest (VOI) containing a previously detected region is segmented by a k-means algorithm in three regions: A central region surrounded by a partial volume region and a spill-out region. All volume outside the VOI (background with all other structures) is handled as a unique basis function and therefore "frozen" in the reconstruction process except for a gain coefficient. The coefficients of the regional basis functions are iteratively estimated with an attenuation-weighted ordered subset expectation maximization (AWOSEM) algorithm in which a 3D, anisotropic, space variant model of point spread function (PSF) is included for resolution recovery. The reconstruction-segmentation process is iterated until convergence; at each iteration, segmentation is performed on the reconstructed image blurred by the system PSF in order to update the partial volume and spill-out regions. The developed PVEC strategy was tested on sphere phantom studies with activity contrasts of 7.5 and 4 and compared to a conventional recovery coefficient method. Improved volume and activity estimates were obtained with low computational costs, thanks to blur recovery and to a better local approximation to ML convergence.

Decreased blood flow with increased metabolic activity: a novel sign of pancreatic tumor aggressiveness

PURPOSE

To study blood flow (BF) and metabolism in normal pancreas and in different pancreatic lesions. We then determined the effect of these biomarkers on outcome in patients with pancreatic cancer.

EXPERIMENTAL DESIGN

Oxygen-15-labeled water and fluorodeoxyglucose positron emission tomography/computed tomography scans were used in 26 patients with a suspicion of pancreatic cancer to measure pancreatic BF and metabolism. In addition, the ratio of standardized uptake value to BF (SUV/BF) was calculated. Patients were divided into three groups: patients with a finding of normal pancreas (n = 7), benign lesions (n = 8), and malignant tumors (n = 11).

RESULTS

Patients with benign and malignant pancreatic tumors had decreased BF of the lesion by 48% and 60%, respectively, compared with patients with normal pancreatic tissue. SUV(max) was 3-fold higher in malignant tumors compared with both benign lesions and normal pancreas (P < 0.05). In contrast, the SUV(max) of patients with benign lesions and normal pancreas did not differ. The SUV/BF ratio was significantly higher in malignant lesions than in benign lesions or in patients with normal pancreas (P < 0.05). In patients with cancer, high SUV/BF ratio was a stronger predictor of poor survival compared with high metabolism or lower-than-normal pancreatic BF.

CONCLUSIONS

BF in pancreatic cancer is significantly reduced compared with the normal pancreas, which may in part explain the poor success of both radiotherapy and chemotherapy. We suggest that the composite measurement of BF and metabolism in pancreatic cancer could serve as a novel tool in the planning of treatments targeting vasculature.

Measuring response with FDG-PET: methodological aspects

The use of fluorodeoxyglucose positron emission tomography (FDG-PET) for the evaluation of tumor response to chemotherapy and radiation therapy has been studied in a number of malignancies. By imaging tumor metabolism and therapy-related changes, FDG-PET has demonstrated advantages over anatomical imaging in the assessment of treatment response. More recent investigations have indicated that FDG-PET can predict tumor response early during the course of therapy, potentially allowing for early treatment adjustments. The aim of this review is to provide oncologists with a basic knowledge of the practical aspects of PET quantification for treatment.

Molecular imaging as a tool for translating breast cancer science

The ability to measure biochemical and molecular processes underlies progress in breast cancer biology and treatment. These assays have traditionally been performed by analysis of cell culture or tissue samples. More recently, functional and molecular imaging has allowed the in vivo assay of biochemistry and molecular biology, which is highly complementary to tissue-based assays. This review briefly describes different imaging modalities used in molecular imaging and then reviews applications of molecular imaging to breast cancer, with a focus on translational work. It includes sections describing work in functional and physiological tumor imaging, imaging gene product expression, imaging the tumor microenvironment, reporter gene imaging, and cell labeling. Work in both animal models and human is discussed with an eye towards studies that have relevance to breast cancer treatment in patients.

Long-term precision of 18F-fluoride PET skeletal kinetic studies in the assessment of bone metabolism

(18)F-Fluoride PET allows noninvasive evaluation of regional bone metabolism and has the potential to become a useful tool for assessing patients with metabolic bone disease and evaluating novel drugs being developed for these diseases. The main PET parameter of interest, termed K(i), reflects regional bone metabolism. The aim of this study was to compare the long-term precision of (18)F-fluoride PET with that of biochemical markers of bone turnover assessed over 6 mo.

METHODS

Sixteen postmenopausal women with osteoporosis or significant osteopenia and a mean age of 64 y underwent (18)F-fluoride PET of the lumbar spine and measurements of biochemical markers of bone formation (bone-specific alkaline phosphatase and osteocalcin) and bone resorption (urinary deoxypyridinoline) at baseline and 6 mo later. Four different methods for analyzing the (18)F-fluoride PET data were compared: a 4k 3-compartmental model using nonlinear regression analysis (K(i-4k)), a 3k 3-compartmental model using nonlinear regression analysis (K(i-3k)), Patlak analysis (K(i-PAT)), and standardized uptake values.

RESULTS

With the exception of a small but significant decrease in K(i-3k) at 6 mo, there were no significant differences between the baseline and 6-mo values for the PET parameters or biochemical markers. The long-term precision, expressed as the coefficient of variation (with 95% confidence interval in parentheses), was 12.2% (9%-19%), 13.8% (10%-22%), 14.4% (11%-22%), and 26.6% (19%-40%) for K(i-3k), K(i-PAT), mean standardized uptake value, and K(i-4k), respectively. For comparison, the precision of the biochemical markers was 10% (7%-15%), 18% (13%-27%), and 14% (10%-21%) for bone-specific alkaline phosphatase, osteocalcin, and urinary deoxypyridinoline, respectively. Intraclass correlation between the baseline and 6-mo values ranged from 0.44 for K(i-4k) to 0.85 for K(i-3k). No significant correlation was found between the repeated mean standardized uptake value measurements.

CONCLUSION

The precision and intraclass correlation observed for K(i-3k) and K(i-PAT) was equivalent to that observed for biochemical markers. This study provided initial data on the long-term precision of (18)F-fluoride PET measured at the lumbar spine, which will aid in the accurate interpretation of changes in regional bone metabolism in response to treatment.

Evolving role of imaging modalities in inflammatory breast cancer

Imaging plays several key roles in the diagnosis and assessment of inflammatory breast cancer (IBC). These include characterization of the known tumor, delineation of locoregional disease in the ipsilateral and contralateral breast and regional lymph node basins, diagnosis of distant metastases, and evaluation of treatment response. We review the role of conventional imaging modalities, including mammography and sonography. We also discuss the potential of using evolving imaging modalities such as magnetic resonance imaging (MRI), positron emission tomography with computed tomography (PET/CT), and more advanced or emerging imaging techniques in the assessment of IBC.

Is there a role for positron emission tomography in breast cancer staging?

Positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) is a radiotracer imaging method that is used in the care of patients with cancer. We conducted a nonsystematic review of the literature regarding the applicability of this technique in patients with breast cancer, encompassing the impact of FDG-PET on surgical management, including axillary node staging and sentinel lymph node biopsy; the use of FDG-PET in the evaluation of the primary tumor; the role of FDG-PET in the evaluation of distant metastases both at diagnosis and in the investigation of suspected recurrence; and the ability of FDG-PET to predict treatment response. FDG-PET is not sufficiently sensitive to replace histologic surgical staging of the axilla. Although FDG avidity of the primary tumor has been shown to be an unfavorable indicator, there is insufficient information to recommend its routine use for this indication. FDG-PET is more sensitive than conventional imaging in the detection of metastatic or recurrent disease, but the impact of increased sensitivity on patient care and outcome has not been demonstrated. The data regarding prediction of treatment response are insufficient to reach any conclusion. There are a number of prospective, adequately powered clinical trials currently in progress that should provide more definitive answers regarding the role, if any, of this technique in the management of patients with breast cancer.

Electromagnetic breast imaging: results of a pilot study in women with abnormal mammograms

PURPOSE

To prospectively assess quantitatively the inherent contrast of electromagnetic (EM) properties that can be imaged by using available technology in women with abnormal findings at conventional breast imaging who underwent subsequent biopsy.

MATERIALS AND METHODS

The protocol was HIPAA compliant and approved by the institutional review board. All participants provided informed consent. Fifty-three women with normal (Breast Imaging Reporting and Data System [BI-RADS] category 1) and ninety-seven women with abnormal (BI-RADS category 4 or 5) screening mammograms were imaged with three EM imaging methods: electrical impedance spectroscopy (EIS), microwave imaging spectroscopy (MIS), and near-infrared spectral tomography (NIR). A region-of-interest (ROI) analysis was used to assess the EM image properties for comparison of findings with conventional image findings and correlation with specific pathologic parameters for women with abnormal findings. Statistical analyses were conducted.

RESULTS

One hundred fifty participants (age range, 35-81 years) were included. EM image property contrast ratios of 150%-200% were found in breast abnormality ROIs relative to the ipsilateral breast background. Analysis of variance demonstrated significant differences in ROI image summaries of mammographically normal versus abnormal breasts for EIS, across diagnostic groups for NIR, and for MIS (analysis restricted to lesions larger than 1 cm(3)). Receiver operating curve (ROC) analysis of the EM properties for cancers among subjects with BI-RADS category 4 or 5, compared with the EM properties for the subjects with normal breasts (BI-RADS category 1), yielded areas under the ROC curve ranging from 0.67 to 0.81. Pathologic correlations with mean vessel density, mean vessel area, and epithelium-to-stroma ratio suggest a biological origin of the EM image properties associated with disease.

CONCLUSION

Results from EM breast examinations provide statistical evidence of a mean increase in image contrast of 150%-200% between abnormal (benign and malignant) and normal breast tissue.

Monitoring of early response to neoadjuvant chemotherapy in stage II and III breast cancer by [18F]fluorodeoxyglucose positron emission tomography

PURPOSE

This study aimed to assess prospectively the efficacy of sequential [18F]fluorodeoxyglucose positron emission tomography (FDG PET) to evaluate early response to neoadjuvant chemotherapy in stage II and III breast cancer patients.

PATIENTS AND METHODS

Images were acquired with a PET/computed tomography scanner in 64 patients after administration of FDG (5 MBq/kg) at baseline and after the first, second, third, and sixth course of chemotherapy. Ultrasound and mammography were used to assess tumor size. Decrease in the standardized uptake value (SUV) with PET was compared with the pathologic response.

RESULTS

Surgery was performed after six courses of chemotherapy and pathologic analysis revealed gross residual disease in 28 patients and minimal residual disease in 36 patients. Although SUV data did not vary much in nonresponders (based on pathology findings), they decreased markedly to background levels in 94% (34 of 36) of responders. When using 60% of SUV at baseline as the cutoff value, the sensitivity, specificity, and negative predictive value of FDG PET were 61%, 96%, and 68% after one course of chemotherapy, 89%, 95%, and 85% after two courses, and 88%, 73%, and 83% after three courses, respectively. The same parameters with ultrasound (US) and mammography were 64%, 43%, and 55%, and 31%, 56%, and 45%, respectively. Assessment of tumor response with US or mammography was never significant whatever the cutoff.

CONCLUSION

Pathologic response to neoadjuvant chemotherapy in stage II and III breast cancer can be predicted accurately by FDG PET after two courses of chemotherapy.

Quantification of FDG PET studies using standardised uptake values in multi-centre trials: effects of image reconstruction, resolution and ROI definition parameters

PURPOSE

Standardised uptake values (SUVs) depend on acquisition, reconstruction and region of interest (ROI) parameters. SUV quantification in multi-centre trials therefore requires standardisation of acquisition and analysis protocols. However, standardisation is difficult owing to the use of different scanners, image reconstruction and data analysis software. In this study we evaluated whether SUVs, obtained at three different institutes, may be directly compared after calibration and correction for inter-institute differences.

METHODS

First, an anthropomorphic thorax phantom containing variously sized spheres and activities, simulating tumours, was scanned and processed in each institute to evaluate differences in scanner calibration. Secondly, effects of image reconstruction and ROI method on recovery coefficients were studied. Next, SUVs were derived for tumours in 23 subjects. Of these 23 patients, four and ten were scanned in two institutes on an HR+ PET scanner and nine were scanned in one institute on an ECAT EXACT PET scanner. All phantom and clinical data were reconstructed using iterative reconstruction with various iterations, with both measured (MAC) and segmented attenuation correction (SAC) and at various image resolutions. Activity concentrations (AC) or SUVs were derived using various ROI isocontours.

RESULTS

Phantom data revealed differences in SUV quantification of up to 30%. After application-specific calibration, recovery coefficients obtained in each institute were equal to within 15%. Varying the ROI isocontour value resulted in a predictable change in SUV (or AC) for both phantom and clinical data. Variation of image resolution resulted in a predictable change in SUV quantification for large spheres/tumours (>5 cc) only. For smaller tumours (<2 cc), differences of up to 40% were found between high (7 mm) and low (10 mm) resolution images. Similar differences occurred when data were reconstructed with a small number of iterations. Finally, no significant differences between MAC and SAC reconstructed data were observed, except for tumours near the diaphragm.

CONCLUSION

Standardisation of acquisition, reconstruction and ROI methods is preferred for SUV quantification in multi-centre trials. Small unavoidable differences in methodology can be accommodated by performing a phantom study to assess inter-institute correction factors.

Positron emission tomography in patients with breast cancer using 18F-3′-deoxy-3′-fluoro-l-thymidine (18F-FLT)—a pilot study

BACKGROUND

This pilot study investigated the feasibility of (18)F-3'-deoxy-3'-fluoro-l-thymidine ((18)F-FLT) as a positron emission tomography (PET) tracer for the visualisation of breast cancer.

METHODS

Patients with breast cancer underwent (18)F-FLT-PET prior to surgery. The uptake of (18)F-FLT was determined in the primary tumour and in the axilla.

RESULTS

Eight tumours were visualized by (18)F-FLT-PET with a mean uptake value (SUV(mean)) of 1.7 and mean tumour-non-tumour ratio (TNT) of 5.0. In seven patients, axillary lymph-node metastases were found at pathological examinations, however, (18)F-FLT-PET showed uptake in only two large (and clinically evident) lymph-node metastases.

CONCLUSIONS

(18)F-FLT shows uptake in most primary breast tumours and in large axillary lymph-node metastases.