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

Relative strengths of three linearizations of receptor availability: Saturation, Inhibition, and Occupancy plots

We derived three widely used linearizations from the definition of receptor availability in molecular imaging with Positron Emission Tomography. The purpose of the present research was to determine the convergence of the results of the three methods in terms of three parameters, occupancy (s), distribution volume of the non-displaceable binding compartment (VND), and binding potential of the radioligand (BPND), in the absence of a gold standard. We tested 104 cases culled from the literature and calculated the goodness of fit of each of the Least Squares (LSM) and Deming II (DM) methods of linear regression when applied to the determination of the three main parameters, s, VND, and BPND, using the goodness of fit parameters R2, coefficient of variation (RMSE), and ‖X‖_∞ with both regression methods. We observed superior convergence among the values of s, VND, and BPND for the Inhibition and Occupancy plots. The Inhibition Plot emerged as the plot with a slightly higher degree of convergence (based on R2, RMSE and ‖X‖_∞ value). With two regression methods, Least Squares (LSM) and Deming II (DM), the estimated values of s, VND, and BPND generally converged. The Inhibition and Occupancy plots yielded the best fits to the data, according to the goodness of fit parameters, due primarily to the absent commingling of the dependent and independent variables tested with the Saturation (original Lassen) plot. In the presence of noise, the Inhibition and Occupancy plots yielded higher convergence.

Sentinel node theory helps tracking of primary lesions of cancers of unknown primary

Background

Sentinel lymph node is the first stop of lymphatic spreading of cancer with known primary. The lymph node metastasis pattern of cancer of unknown primary (CUP) is unclear and has been presumed to follow the same pathway. To test this hypothesis, data of all 716 patients clinically diagnosed as CUP in our center were collected.

Methods

Diagnoses of lymph node metastasis were established by ¹⁸F-FDG PET-CT and/or biopsy pathology. Three hundred and forty-seven cases meeting the criteria were divided into three groups: pathology-confirmed primary with invasive biopsy or surgery of the suspicious lesion (group A, n = 64), primary still unknown even with invasive biopsy or surgery of the suspicious lesion (group B, n = 204), and others with no suspicious lesion or lesions who had not been sampled due to medical or other reasons (group C, n = 79). We assessed the clinicopathological features between these groups, and the relationship between lymph node metastasis pattern and confirmed primary site.

Results

In group A, the primary sites of 61 cases were compatible with sentinel node theory, resulting in a positive predictive value of 95%. No significant differences in age, sex, bone metastasis, or visceral metastasis observed between group A and group B, except that group A had a higher ratio of differentiated carcinoma (94% vs. 77%, P = 0.003).

Conclusion

To our knowledge, this is the first evidence indicating that the majority of clinical CUP cases follow the sentinel node theory to spread in lymph nodes, which helps tracking the primary, especially for differentiated carcinoma.

Nuclear Medicine Imaging Techniques for Detection of Skeletal Metastases in Breast Cancer

Bone is the most common site of metastases from advanced breast cancer. Whole-body bone scintigraphy has been most frequently used in the process of managing cancer patients; its advantage is that it provides rapid whole-body imaging for screening of osteoblastic or sclerotic/mixed bone metastases at reasonable cost. Recent advanced techniques, such as single-photon emission computed tomography (SPECT)/CT, quantitative analysis, and bone scan index, contribute to better understanding of the disease state. More recent advances in machines and PET drugs improve the staging of the skeleton with higher sensitivity and specificity.

Comparison of Diagnostic Performance of Three-Dimensional Positron Emission Mammography versus Whole Body Positron Emission Tomography in Breast Cancer

Objective

To compare the diagnostic performance of three-dimensional (3D) positron emission mammography (PEM) versus whole body positron emission tomography (WBPET) for breast cancer.

Methods

A total of 410 women with normal breast or benign or highly suspicious malignant tumors were randomized at 1 : 1 ratio to undergo 3D-PEM followed by WBPET or WBPET followed by 3D-PEM. Lumpectomy or mastectomy was performed on eligible participants after the scanning.

Results

The sensitivity and specificity of 3D-PEM were 92.8% and 54.5%, respectively. WBPET showed a sensitivity of 95.7% and specificity of 56.8%. After exclusion of the patients with lesions beyond the detecting range of the 3D-PEM instrument, 3D-PEM showed higher sensitivity than WBPET (97.0% versus 95.5%, P = 0.913), particularly for small lesions (<1 cm) (72.0% versus 60.0%, P = 0.685).

Conclusions

The 3D-PEM appears more sensitive to small lesions than WBPET but may fail to detect lesions that are beyond the detecting range. This study was approved by the Ethics Committee (E2012052) at the Tianjin Medical University Cancer Institute and Hospital (Tianjin, China). The instrument positron emission mammography (PEMi) was approved by China State Food and Drug Administration under the registration number 20153331166.

Diagnostic clue of nodular fasciitis mimicking metastasis in papillary thyroid cancer, mismatching findings on 18F-FDG PET/CT and 123I whole body scan: A case report

This study reports a case of nodular fasciitis incidentally detected in a patient with papillary thyroid cancer. A 47-year-old woman underwent a total thyroidectomy and radioactive iodine therapy for papillary thyroid cancer. On a follow-up fluorodeoxyglucose (¹⁸F-FDG) PET/computed tomography (CT) scan after 12 months, a focal ¹⁸F-FDG-avid lesion was incidentally detected in the paraspinal muscle. It was well-enhanced on CT and magnetic resonance imaging, indicating metastasis. However, the lesion was not iodine avid on the ¹²³I whole body scan, which favored benign etiology over metastasis from thyroid cancer. For pathological confirmation, surgical excision was performed and the paraspinal lesion was finally confirmed as nodular fasciitis. Therefore, it was suggested that nodular fasciitis may be included in the differential diagnosis of a ¹⁸F-FDG avid/iodine non-avid soft tissue lesion in patients with thyroid cancer. In such circumstances, ¹²³I whole body scans may serve a role in non-invasive work-up, and prevent unnecessary surgical procedures.

Increase in Distant Stage Breast Cancer Incidence Rates in US Women Aged 25-49 Years, 2000-2011: The Stage Migration Hypothesis

Background. Unexplained increases have been reported in incidence rates for breast cancer diagnosed at distant stage in younger U.S. women, using data from the Surveillance, Epidemiology and End Results (SEER) Program. Methods. This report focused on recent SEER trends (2000–2011) in age-standardized incidence rates of invasive breast cancer at ages 25–39 and 40–49 years and the hypothesis that stage migration may have resulted from advances in detecting distant metastases at diagnosis. Results. Increases in the rates for distant stage were roughly equal to decreases in the rates for the most advanced stage subgroups within regional stage; this was evident for estrogen receptor (ER) negative cancers, associated with poorer prognosis, but not for ER positive cancers. The 3-year relative survival rate increased over time for distant stage (especially in the ER positive subgroup) and regional stage but not for localized stage; these trends do not contradict the stage-migration hypothesis. Conclusions. Findings provide some support for stage migration as one explanation for the recent increase in incidence of distant stage breast cancer, but additional studies are needed using other databases.

Positron emission tomography: clinical applications in oncology. Part 1

Positron emission tomography is a functional diagnostic imaging technique, which can accurately measure in vivo distribution of a radiopharmaceutical with high resolution. The ability of positron emission tomography to study various biologic processes opens up new possibilities for both research and day-to-day clinical use. Positron emission tomography has progressed rapidly from being a research technique in laboratories to a routine clinical imaging modality becoming part of armamentarium for the medical profession. The most widely used radiotracer in positron emission tomography is 18F-fluoro-2-deoxy-D-glucose (FDG), which is an analog of glucose. FDG uptake in cells is directly proportional to glucose metabolism of cells. Since glucose metabolism is increased many fold in malignant tumors, positron emission tomography has a high sensitivity and high negative predictive value. Positron emission tomography with FDG is now the standard of care in initial staging, monitoring the response to therapy and management of lung cancer, colorectal cancer, lymphoma, melanoma, esophageal cancer, head and neck cancer and breast cancer. The aim of this article is to review the clinical applications of positron emission tomography in oncology.

The role of FDG-PET-CT in the evaluation of primary systemic therapy in breast cancer: links between metabolic and pathological remission

Introduction: FDG-PET-CT is highly sensitive in detection of viable tumour tissue, giving an importance for that in oncological diagnostics. Aim: The authors analysed retrospectively the relationship between metabolic response and changes in Ki-67, a proliferation marker. Methods: Staging FDG-PET-CT scans (before and after therapy) SUVs (Standardized Uptake Value), and morphological changes in the primary tumour and axillary lymph node region were evaluated in 30 patients with breast cancer. Calculated ΔSUV were compared with Ki-67 proliferation marker (measured in biopsies and surgical specimens). Results: The decrease of SUV and size were significant in the primary tumour and the axillary lymph node region. Decrease of Ki-67 was significant. Significant correlation was found between Ki-67 and SUV before therapy, initial Ki-67 and ΔSUV, and ΔKi-67 and ΔSUV. Conclusions: The metabolic changes were more sensitive in the measurement of the therapeutic response than morphological remission, and they correlated well with the pathological response, in not standardized clinical conditions even. Orv. Hetil., 2012, 153, 1958–1964.

Comparison of the diagnostic value of FDG-PET/CT and axillary ultrasound for the detection of lymph node metastases in breast cancer patients

BACKGROUND

FDG-PET/CT is increasingly being used for breast cancer staging. Its diagnostic accuracy in comparison to ultrasound as the standard non-invasive imaging modality for the evaluation of axillary lymph nodes has yet not been evaluated.

PURPOSE

To retrospectively compare the diagnostic value of full-dose, intravenously contrast-enhanced FDG-PET/CT and ultrasound for the detection of lymph node metastases in breast cancer patients.

MATERIAL AND METHODS

Ninety patients (one patient with a bilateral carcinoma) (89 women, one man; mean age, 55.5 +/- 16.6 years) suffering from primary breast cancer underwent whole-body FDG-PET/CT and axillary ultrasound. The ipsilateral axillary fossa (n = 91) was evaluated for metastatic spread. The sensitivity, specificity, the positive predictive value (PPV), negative predictive value (NPV), and accuracy of both methods were calculated. The sensitivity and accuracy were statistically compared using the McNemar Test (P <0.05). Analyses were made on a patient basis. The number of patients with extra-axillary locoregional lymph node metastases exclusively detected by FDG-PET/CT was evaluated. For axillary lymph node metastases histopathology served as the reference standard.

RESULTS

The sensitivity, specificity, PPV, NPV, and accuracy of FDG-PET/CT for the detection of axillary lymph node metastases were 54%, 89%, 77%, 74%, and 75%, respectively. For ultrasound it was 38%, 78%, 54%, 65%, and 62%, respectively. FDG-PET/CT was significantly more accurate than ultrasound for the detection of axillary lymph node metastases (P = 0.019). There was no statistically significant difference between the sensitivity of both modalities (P = 0.0578). FDG-PET/CT detected extra-axillary locoregional lymph node metastases in seven patients (8%) that had not been detected by another imaging modality.

CONCLUSION

Though more accurate compared to ultrasound for evaluating the axillary lymph node status FDG-PET/CT is only as sensitive as ultrasound when it comes to the detection of axillary lymph node metastases. Due to the low sensitivity FDG-PET/CT cannot act as a substitute for Sentinel lymph node biopsy. FDG-PET/CT is able to detect previously unknown locoregional extra-axillary lymph node metastases.

Molecular Imaging in Breast Cancer - Potential Future Aspects

SUMMARY: Molecular imaging aims to visualize and quantify biological, physiological, and pathological processes at cellular and molecular levels. Recently, molecular imaging has been introduced into breast cancer imaging. In this review, we will present a survey of the molecular imaging techniques that are either clinically available or are being introduced into clinical imaging. We will discuss nuclear imaging and multiparametric magnetic resonance imaging as well as the combined application of molecular imaging in the assessment of breast lesions. In addition, we will briefly discuss other evolving molecular imaging techniques, such as phosphorus magnetic resonance spectroscopic imaging and sodium imaging.

PET-guided breast biopsy

Molecular imaging, using positron emission tomography (PET), has become an integral step in the evaluation of many patients with malignancy. However, its use in patients with breast cancer has been limited by the lower levels of (18) F-fluorodeoxyglucose (FDG) uptake in some breast malignancies compared to other cancers, the small size of many breast cancers, and the need for biopsy under PET guidance. High-resolution breast PET, or positron emission mammography (PEM), with biopsy guidance software, now addresses these issues. We report a prospective, multicenter study designed to test the efficacy and safety of PEM biopsy guidance software in women with FDG-avid breast lesions worrisome for malignancy. The intervention chosen was vacuum-assisted core biopsy. Nineteen subjects underwent a total of 24 PEM-guided biopsies. All lesions were successfully targeted and sampled as determined by post-biopsy image scan evaluation, specimen imaging, and pathologic concordance. Invasive cancer was identified in 13 of 24 lesions (54%), while four (17%) were high-risk lesions and three of these were upgraded to malignancy at excision. No serious adverse events occurred and all patients found the procedure to cause only minimal to mild discomfort. High-resolution PEM-guided breast biopsy is both safe and effective for the sampling of PET-depicted breast lesions.

Positron emission mammography in breast cancer presurgical planning: comparisons with magnetic resonance imaging

PURPOSE

The objective of this study was to compare the performance characteristics of (18)F-fluorodeoxyglucose (FDG) positron emission mammography (PEM) with breast magnetic resonance imaging (MRI) as a presurgical imaging and planning option for index and ipsilateral lesions in patients with newly diagnosed, biopsy-proven breast cancer.

METHODS

Two hundred and eight women >25 years of age (median age = 59.7 ± 14.1 years) with biopsy-proven primary breast cancer enrolled in this prospective, single-site study. MRI, PEM, and whole-body positron emission tomography (WBPET) were conducted on each patient within 7 business days. PEM and WBPET images were acquired on the same day after intravenous administration of 370 MBq of FDG (median = 432.9 MBq). PEM and MRI images were blindly evaluated, compared with final surgical histopathology, and the sensitivity determined. Substudy analysis compared the sensitivity of PEM versus MRI in patients with different menopausal status, breast density, and use of hormone replacement therapy (HRT) as well as determination of performance characteristics for additional ipsilateral lesion detection.

RESULTS

Two hundred and eight patients enrolled in the study of which 87% (182/208) were analyzable. Of these analyzable patients, 26.4% (48/182), 7.1% (13/182), and 64.2% (120/182) were pre-, peri-, and postmenopausal, respectively, and 48.4% (88/182) had extremely or heterogeneously dense breast tissue, while 33.5% (61/182) had a history of HRT use. Ninety-two percent (167/182) underwent core biopsy for index lesion diagnosis. Invasive cancer was found in 77.5% (141/182), while ductal carcinoma in situ (DCIS) and/or Paget's disease were found in 22.5% (41/182) of patients. Both PEM and MRI had index lesion depiction sensitivity of 92.8% and both were significantly better than WBPET (67.9%, p < 0.001, McNemar's test). For index lesions, PEM and MRI had equivalent sensitivity of various tumors, categorized by tumor stage as well as similar invasive tumor size predictions with Spearman's correlation coefficient of 0.61 for both PEM and MRI compared to surgical pathology. Menopausal status, breast density, and HRT did not influence the sensitivity of PEM or MRI. For 67 additional unsuspected ipsilateral lesions or multifocal lesions, PEM had sensitivity of 85% (34/40) and specificity of 74%, (20/27) compared to MRI's sensitivity of 98% (39/40) and specificity of 48% (13/27) [p = 0.074, for sensitivity; p = 0.096 for specificity]

CONCLUSION

PEM is a good alternative to MRI as a presurgical breast imaging option and its performance characteristics are not affected by patient menopausal/hormonal status or breast density.

Role of fusion of prone FDG-PET and magnetic resonance imaging of the breasts in the evaluation of breast cancer

The purpose of this study is to report further about the statistically significant results from a prospective study, which suggests that fusion of prone F-18 Fluoro-deoxy-glucose (FDG) positron emission tomography (PET) and magnetic resonance (MR) breast scans increases the positive predictive value (PPV) and specificity for patients in whom the MR outcome alone would be nonspecific. Thirty-six women (mean age, 43 years; range, 24-65 years) with 90 lesions detected on MR consented to undergo a FDG-PET scan. Two blinded readers evaluated the MR and the computer tomography (CT) attenuation-corrected prone FDG-PET scans side-by-side, then after the volumes were superimposed (fused). A semiautomatic, landmark-based program was used to perform nonrigid fusion. Pathology and radiologic follow-up were used as the reference standard. The sensitivity, specificity, PPV, negative predictive value (NPV), and accuracy (with 95% confidence intervals) for MR alone, FDG-PET alone, and fused MR and FDG-PET were calculated. The median lesion size measured from the MR was 2.5 cm (range, 0.5-10 cm). Histologically, 56 lesions were malignant, and 15 were benign. Nineteen lesions were benign after 20-47 months of clinical and radiologic surveillance. The sensitivity of MR alone was 95%, FDG-PET alone was 57%, and fusion was 83%. The increase in PPV from 77% in MR alone to 98% when fused and the increase in specificity from 53% to 97% were statistically significant (p < 0.05). The false-negative rate on FDG-PET alone was 26.7%, and after fusion this number was reduced to 9%. FDG-PET and MR fusions were helpful in selecting which lesion to biopsy, especially in women with multiple suspicious MR breast lesions.

Design study of a high-resolution breast-dedicated PET system built from cadmium zinc telluride detectors

We studied the performance of a dual-panel positron emission tomography (PET) camera dedicated to breast cancer imaging using Monte Carlo simulation. The proposed system consists of two 4 cm thick 12 x 15 cm(2) area cadmium zinc telluride (CZT) panels with adjustable separation, which can be put in close proximity to the breast and/or axillary nodes. Unique characteristics distinguishing the proposed system from previous efforts in breast-dedicated PET instrumentation are the deployment of CZT detectors with superior spatial and energy resolution, using a cross-strip electrode readout scheme to enable 3D positioning of individual photon interaction coordinates in the CZT, which includes directly measured photon depth-of-interaction (DOI), and arranging the detector slabs edge-on with respect to incoming 511 keV photons for high photon sensitivity. The simulation results show that the proposed CZT dual-panel PET system is able to achieve superior performance in terms of photon sensitivity, noise equivalent count rate, spatial resolution and lesion visualization. The proposed system is expected to achieve approximately 32% photon sensitivity for a point source at the center and a 4 cm panel separation. For a simplified breast phantom adjacent to heart and torso compartments, the peak noise equivalent count (NEC) rate is predicted to be approximately 94.2 kcts s(-1) (breast volume: 720 cm(3) and activity concentration: 3.7 kBq cm(-3)) for a approximately 10% energy window around 511 keV and approximately 8 ns coincidence time window. The system achieves 1 mm intrinsic spatial resolution anywhere between the two panels with a 4 cm panel separation if the detectors have DOI resolution less than 2 mm. For a 3 mm DOI resolution, the system exhibits excellent sphere resolution uniformity (sigma(rms)/mean) < or = 10%) across a 4 cm width FOV. Simulation results indicate that the system exhibits superior hot sphere visualization and is expected to visualize 2 mm diameter spheres with a 5:1 activity concentration ratio within roughly 7 min imaging time. Furthermore, we observe that the degree of spatial resolution degradation along the direction orthogonal to the two panels that is typical of a limited angle tomography configuration is mitigated by having high-resolution DOI capabilities that enable more accurate positioning of oblique response lines.

Axillary node staging by ultrasonography and fine-needle aspiration cytology in patients with breast cancer

Background

This study evaluated the role of axillary ultrasonography (AUS) and fine-needle aspiration cytology (FNAC) in preoperative staging of the axilla in patients with invasive breast cancer.

Methods

Between October 2006 and March 2009, 502 patients scheduled to undergo surgery for invasive breast cancer had preoperative AUS. All patients with suspicious nodes on ultrasonography underwent FNAC, and those with positive cytology proceeded directly to axillary node clearance. Patients with normal findings on AUS or negative cytology underwent sentinel node biopsy (SNB).

Results

A total of 137 (27·3 per cent) of 502 patients had axillary node metastases on final histology. Thirty-nine (28·5 per cent) node-positive patients were identified by AUS–FNAC and spared unnecessary SNB. AUS–FNAC had a sensitivity of 28·5 per cent and a specificity of 100 per cent for detecting axillary nodal metastases. AUS–FNAC findings were normal in all 15 patients with nodal micrometastases and in 11 patients with isolated tumour cells on histopathology. The sensitivity of AUS–FNAC had a positive correlation with invasive tumour size (odds ratio 1·03) and grade (odds ratio 2·80).

Conclusion

Preoperative AUS–FNAC avoided unnecessary SNB in 28·5 per cent of node-positive patients and in 7·8 per cent of patients overall.

Obtaining adequate surgical margins in breast-conserving therapy for patients with early-stage breast cancer: current modalities and future directions

Inadequate surgical margins represent a high risk for adverse clinical outcome in breast-conserving therapy (BCT) for early-stage breast cancer. The majority of studies report positive resection margins in 20% to 40% of the patients who underwent BCT. This may result in an increased local recurrence (LR) rate or additional surgery and, consequently, adverse affects on cosmesis, psychological distress, and health costs. In the literature, various risk factors are reported to be associated with positive margin status after lumpectomy, which may allow the surgeon to distinguish those patients with a higher a priori risk for re-excision. However, most risk factors are related to tumor biology and patient characteristics, which cannot be modified as such. Therefore, efforts to reduce the number of positive margins should focus on optimizing the surgical procedure itself, because the surgeon lacks real-time intraoperative information on the presence of positive resection margins during breast-conserving surgery. This review presents the status of pre- and intraoperative modalities currently used in BCT. Furthermore, innovative intraoperative approaches, such as positron emission tomography, radioguided occult lesion localization, and near-infrared fluorescence optical imaging, are addressed, which have to prove their potential value in improving surgical outcome and reducing the need for re-excision in BCT.

18F-Fluoride positron emission tomography and positron emission tomography/computed tomography

(18)F-Fluoride is a positron-emitting bone-seeking agent, the uptake of which reflects blood flow and remodeling of bone. Assessment of (18)F-fluoride kinetics using quantitative positron emission tomography (PET) methods allows the regional characterization of lesions of metabolic bone diseases and the monitoring of their response to therapy. It also enables the assessment of bone viability and discrimination of uneventful and impaired healing processes of fractures, bone grafts and osteonecrosis. Taking advantage of the favorable pharmacokinetic properties of the tracer combined with the high performance of PET technology, static (18)F-fluoride PET is a highly sensitive imaging modality for detection of benign and malignant osseous abnormalities. Although (18)F-fluoride uptake mechanism corresponds to osteoblastic activity, it is also sensitive for detection of lytic and early marrow-based metastases, by identifying their accompanying reactive osteoblastic changes, even when minimal. The instant fusion of increased (18)F-fluoride uptake with morphological data of computed tomography (CT) using hybrid PET/CT systems improves the specificity of (18)F-fluoride PET in cancer patients by accurately differentiating between benign and malignant sites of uptake. The results of a few recent publications suggest that (18)F-fluoride PET/CT is a valuable modality in the diagnosis of pathological osseous conditions in patients also referred for nononcologic indications. (18)F-fluoride PET and PET/CT are, however, not widely used in clinical practice. The limited availability of (18)F-fluoride and of PET and PET/CT systems is a major factor. At present, there are not enough data on the cost-effectiveness of (18)F-fluoride PET/CT. However, it has been stated by some experts that (18)F-fluoride PET/CT is expected to replace (99m)Tc-MDP bone scintigraphy in the future.

High-Resolution Fluorodeoxyglucose Positron Emission Tomography with Compression ("Positron Emission Mammography") is Highly Accurate in Depicting Primary Breast Cancer

We sought to prospectively assess the diagnostic performance of a high-resolution positron emission tomography (PET) scanner using mild breast compression (positron emission mammography [PEM]). Data were collected on concomitant medical conditions to assess potential confounding factors. At four centers, 94 consecutive women with known breast cancer or suspicious breast lesions received 18F-fluorodeoxyglucose (FDG) intravenously, followed by PEM scans. Readers were provided clinical histories and x-ray mammograms (when available). After excluding inevaluable cases and two cases of lymphoma, PEM readings were correlated with histopathology for 92 lesions in 77 women: 77 index lesions (42 malignant), 3 ipsilateral lesions (3 malignant), and 12 contralateral lesions (3 malignant). Of 48 cancers, 16 (33%) were clinically evident; 11 (23%) were ductal carcinoma in situ (DCIS), and 37 (77%) were invasive (30 ductal, 4 lobular, and 3 mixed; median size 21 mm). PEM depicted 10 of 11 (91%) DCIS and 33 of 37 (89%) invasive cancers. PEM was positive in 1 of 2 T1a tumors, 4 of 6 T1b tumors, 7 of 7 T1c tumors, and 4 of 4 cases where tumor size was not available (e.g., no surgical follow-up). PEM sensitivity for detecting cancer was 90%, specificity 86%, positive predictive value (PPV) 88%, negative predictive value (NPV) 88%, accuracy 88%, and area under the receiver-operating characteristic curve (Az) 0.918. In three patients, cancer foci were identified only on PEM, significantly changing patient management. Excluding eight diabetic subjects and eight subjects whose lesions were characterized as clearly benign with conventional imaging, PEM sensitivity was 91%, specificity 93%, PPV 95%, NPV 88%, accuracy 92%, and Az 0.949 when interpreted with mammographic and clinical findings. FDG PEM has high diagnostic accuracy for breast lesions, including DCIS.

Accuracy of ultrasonography and 99mTc-sestamibi scintimammography for assessing axillary lymph node status in breast cancer patients. A prospective study

AIMS

The aim of this study was to evaluate the sensitivity, specificity and accuracy of axillary ultrasonography (US) and (99m)Tc-sestamibi scintimammography (SSM) in patients with breast cancer (BC) undergoing curative surgery.

METHODS

A series of 77 consecutive women (median age 54 years, range 36-70) with primary BC underwent both US and SSM from 2 to 15 (median 4) days prior to curative surgery. The results of imaging studies were compared against the final pathology. Breast-conserving surgery with axillary node (AN) dissection was performed in 49 (63.6%) patients, and modified radical mastectomy in 28 (36.4%) patients, according to the tumour staging.

RESULTS

Final pathology showed 5 pT1bN0, 1 pT1bN1, 28 pT1cN0, 19 pT1cN1, 7 pT2N0, and 17 pT2N1 BC. Overall, 719 AN were removed of which 106 (14.7%) were metastatized nodes (median 3, range 1-5 per patient). The sensitivity, specificity and accuracy were 67.6%, 80.0%, and 74.0% for US, 78.4%, 85.0%, and 81.8% for SSM, and 91.9%, 92.5%, and 92.2% for US and SSM together, respectively. There was a significant difference (p<0.05) in the number of metastatized AN between patients with metastases correctly detected and undetected by both US (3.1+/-1.3 vs. 2.0+/-0.7) and SSM (3.2+/-1.3 vs. 1.7+/-0.7).

CONCLUSIONS

Although the results of each diagnostic tests are strictly dependent on the number of the metastatized AN, the combination of axillary US and SSM is a sensitive low-cost procedure that should be suggested in all patients with BC, when a preoperative evaluation of the AN status is required.

MRI/PET nonrigid breast-image registration using skin fiducial markers

We propose a finite-element method (FEM) deformable breast model that does not require elastic breast data for nonrigid PET/MRI breast image registration. The model is applicable only if the stress conditions in the imaged breast are virtually the same in PET and MRI. Under these conditions, the observed intermodality displacements are solely due the imaging/reconstruction process. Similar stress conditions are assured by use of an MRI breast-antenna replica for breast support during PET, and use of the same positioning. The tetrahedral volume and triangular surface elements are used to construct the FEM mesh from the MRI image. Our model requires a number of fiducial skin markers (FSM) visible in PET and MRI. The displacement vectors of FSMs are measured followed by the dense displacement field estimation by first distributing the displacement, vectors linearly over the breast surface and then distributing them throughout the volume. Finally, the floating MRI image is warped to a fixed PET image, by using an appropriate shape function in the interpolation from mesh nodes to voxels. We tested our model on an elastic breast phantom with simulated internal lesions and on a small number of patients imaged, with FMS using PET and MRI. Using simulated lesions (in phantom) and real lesions (in patients) visible in both PET and MRI, we established that the target registration error (TRE) is below two pet voxels.

Initial experience with FDG-PET/CT in the evaluation of breast cancer

PURPOSE

We retrospectively reviewed FDG-PET/CT images in patients with breast cancer to determine whether PET/CT improved the level of diagnostic confidence as compared with PET and to compare PET/CT and CT findings at the location of suspected malignancies.

METHODS

The study included 75 patients with known breast cancer. The initial PET/CT study for each patient was retrospectively reviewed to determine whether improved diagnostic confidence (IDC) regarding lesion localization and characterization was observed with PET/CT as compared with PET alone. PET/CT and CT findings were compared regarding lesion characterization and staging in 69 of the 75 patients, and in the case of discordant findings, comparison with histological or informative follow-up results was also performed.

RESULTS

Fifty of the 75 patients exhibited increased FDG uptake in a total of 95 regions. In the comparison of PET/CT and PET, PET/CT resulted in IDC in 30 (60%) of these 50 patients and in 52 (55%) of the 95 regions. In the comparison between PET/CT and CT in 69 patients, PET/CT demonstrated a significantly better accuracy than CT (P<0.05). PET/CT showed definitely positive findings in 60 regions with malignancies, among which CT exhibited positive findings in 43 (72%). PET/CT and CT accurately staged 59 (86%) and 53 (77%) of the 69 patients, respectively.

CONCLUSIONS

PET/CT added incremental diagnostic confidence to PET in more than 50% of patients and regions with increased FDG uptake. PET/CT accurately detected more regions with malignancies than did CT. This initial evaluation suggests that PET/CT is preferable to PET or CT in the diagnosis of breast cancer.

PET and cancer screening

Various carcinomas are discovered incidentally during FDG PET study. This points to the potential use of PET as a cancer screening modality. Our experience using three PET scanners showed that PET can be performed in many individuals, and a wide variety of carcinomas can be detected at potentially curable stages. PET screening targets various organs that conventional organ-specific screening tests cannot cover. PET used simultaneously with conventional tests can prevent the overlooking of cancer, reduce false-positive results, and assist in the interpretation of CT and MR images. Thus, PET can play a supportive role when used with conventional screening tests. To reduce false-positive and false-negative results in PET screening, however, experienced PET oncologists who can differentiate between distinct physiological FDG uptake and faint abnormal FDG uptake are needed. In Japan, more than half of the PET facilities offer PET examinations for cancer screening of asymptomatic persons. Not a few individuals pay for sophisticated cancer screenings. Guidelines concerning the use of PET for cancer screening were issued by the Japanese Society of Nuclear Medicine in 2004. The guidelines provide for maintenance of study quality and warn of overselling PET screening. It is unclear how much PET contributes to sophisticated cancer screening. Data are lacking as to whether mortality is reduced by PET screening. Scientific evidence should be presented demonstrating the value of PET in cancer screening.

Detection of Primary Breast Carcinoma with a Dedicated, Large-Field-of-View FDG PET Mammography Device: Initial Experience

PURPOSE

To prospectively assess a dedicated, large field of view positron emission tomography (PET) mammographic device for imaging primary breast carcinoma.

MATERIALS AND METHODS

Institutional review board approval was obtained for this study, and all patients provided written informed consent prior to participation. Subjects were recruited from a cohort of patients in whom diagnostic mammography and/or ultrasonography demonstrated lesions that were highly suggestive of malignancy. Twenty-three patients who met the inclusion criteria were subsequently imaged by using a dedicated PET mammography unit that was developed in conjunction with the Thomas Jefferson National Accelerator Facility (Newport News, Va). One hour after administration of 2.0-2.5 mCi (74.0-93.5 MBq) of fluorodeoxyglucose, 5-minute PET mammography of the affected breast was performed. Images were processed and reconstructed in the transverse craniocaudal and coronal planes. For each lesion, image-guided core-needle biopsy was performed immediately after PET mammography. Conventional mammography results and histologic findings were correlated with PET mammography images. The sensitivity, specificity, negative predictive value, and positive predictive value of PET mammography for demonstrating malignant lesions were calculated.

RESULTS

PET mammography demonstrated 20 focal abnormalities, of which 18 were malignant and two were benign. Both benign lesions represented areas of fat necrosis. Three of 20 malignant lesions demonstrated at conventional mammography were not demonstrated at PET mammography. The overall sensitivity of PET mammography for malignancy was 86% (95% confidence interval: 65%, 95%), with a positive predictive value of 90% (95% confidence interval: 70%, 97%). The calculated specificity was 33% (95% confidence interval: 2%, 79%), and the negative predictive value was 25% (95% confidence interval: 1%, 70%).

CONCLUSION

These pilot data suggest that PET mammography can demonstrate small primary breast malignancies.

PET: a revolution in medical imaging

FDG-PET has had remarkable influence on the assessment of physiologic and pathologic states. The authors predict that FDG-PET imaging could soon become the most common procedure used by nuclear medicine laboratories and could remain so for an extended period of time. The power of molecular imaging lies in the vast potential for using biochemical and pharmacologic probes to extend applications arising from an understanding of cell biology to a large number of well-characterized pathologic states. Molecular imaging based upon tracer kinetics with positron-emitting radiopharmaceuticals could become the main source of information for the management of cancer patients. In that case, nuclear medicine procedures might become the most common imaging studies performed in the practice of medicine. This speculation is not farfetched when one realizes the enormous change that a single biologically important compound, FDG, has brought to the medical arena. The major challenge today is to attract the highly qualified individuals and to secure the resources needed to harness the opportunities in the specialty of molecular imaging.

Bone imaging in metastatic breast cancer

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

An overview of the status of imaging screening technology for breast cancer

With breast cancer incidence rates showing no signs of abating, advances in risk stratification and increasing awareness of cancer control, there is interest in expanding the breast imaging arsenal. Mammography is still the standard of care, and a recent meta-analysis of seven large studies supports its value as a screening tool. There is, however, clear need for improved sensitivity and specificity. Imaging of function, metabolism and molecular activity in breast tissue is of potential benefit in addressing these issues. In this article we provide an overview of the current methods of imaging in breast cancer, including mammography, ultrasound, digital mammography, magnetic resonance, positron emission tomography and magnetic resonance spectroscopy. Screening and surveillance should, ideally, be tailored to an individual's cancer risk and breast tissue. Current evidence questions the recent move toward magnetic resonance imaging as a single or multimodality strategy for breast cancer screening. In a high-risk group, the cost effectiveness of technical innovations may be justified.

Implications of PET based molecular imaging on the current and future practice of medicine

The last quarter century has witnessed the introduction of a variety of powerful techniques that have allowed visualization of organ structure and function with exquisite detail. This in turn has brought about a true revolution in the day-to-day practice of medicine. Structural imaging with x-ray computerized tomography and magnetic resonance imaging has added tremendously to many areas of medicine, including preoperative evaluation of patients. Many surgical procedures have been replaced by minimally invasive techniques, which have become a reality only because of the availability of modern imaging modalities. However, despite such accomplishments, structural imaging is quite insensitive for detecting early disease in which there often are no gross structural alterations in organ anatomy. Therefore, these modalities should be complemented by methodologies that can detect abnormalities at the molecular and cellular levels. The introduction of [(18)F]-fluorodeoxyglucose positron emission tomography (FDG-PET) in 1976 as a molecular imaging technique clearly has shown the power of this approach for treating a multitude of serious disorders. The impact of FDG-PET has been particularly impressive in patients with cancer diagnosis, for whom it has become important in staging, monitoring response to treatment, and detecting recurrence. In this review, we emphasize the role of FDG-PET in the assessment of central nervous system maladies, malignant neoplastic processes, infectious and inflammatory diseases, and cardiovascular disorders. New radiotracers are being developed and promise to expand further the list of indications for PET. These include novel tracers for cancer diagnosis and treatment capable of detecting hypoxia and angiogenesis. Prospects for developing new tracers for imaging other organ diseases also appear very promising.

Diagnosis of axillary nodal metastases by ultrasound-guided core biopsy in primary operable breast cancer

The purpose of this study was to examine the use of ultrasound (US)-guided core biopsy of axillary nodes in patients with operable breast cancer. The ipsilateral axillae of 187 patients with suspected primary operable breast cancer were scanned. Nodes were classified based on their shape and cortical morphology. Abnormal nodes underwent US-guided core biopsy/fine needle aspiration (FNA), and the results correlated with subsequent axillary surgery. The nodes were identified on US in 103 of 166 axillae of patients with confirmed invasive carcinoma. In total, 54 (52%) met the criteria for biopsy: 48 core biopsies (26 malignant, 20 benign node, two normal) and six FNA were performed. On subsequent definitive histological examination, 64 of 166 (39%) had axillary metastases. Of the 64 patients with involved nodes at surgery, preoperative US identified nodes in 46 patients (72%), of which 35 (55%) met the criteria for biopsy and 27 (42%) of these were diagnosed preoperatively by US-guided biopsy. In conclusion, US can identify abnormal nodes in patients presenting with primary operable breast cancer. In all, 65% of these nodes are malignant and this can often be confirmed with US-guided core biopsy.

The follow-up of breast cancer

Adenocarcinoma of the breast is the most common cancer of American women. Increased incidence and reduced mortality have generated a population of more than 2 million breast cancer survivors who require medical follow-up. In addition to therapy-related complications, these women are at risk for locoregional recurrence, distant relapse, and the development of second primary breast tumors. Medical surveillance after primary breast cancer treatment has historically included regular patient history and physical examinations, complete blood cell counts, comprehensive blood chemistries, tumor markers, mammography, chest x-rays, and sometimes computed tomography (CT) and nuclear medicine bone scans. The use of such intensive surveillance was based on the presumption that detecting disease recurrence at its earliest stage would offer the chance of cure, improved survival, or at least improved quality of life. Here we review the evidence that such intensive surveillance is not cost-effective, and in fact has no significant impact on the overall survival or quality of life of women diagnosed with early-stage breast cancer. Finally, we present an evidence-based approach to breast cancer surveillance after therapy that is consistent with several clinical practice guidelines, maximizing outcome and minimizing cost.

Method for combined FDG-PET and radiographic imaging of primary breast cancers

The purpose of the study was to demonstrate the feasibility of a hybrid functional/anatomic breast imaging platform with biopsy capability for facilitating lesion detection and diagnosis. This platform consists of an investigative dedicated positron emission mammography (PEM) device mounted on a stereotactic X-ray mammography system, permitting sequential acquisition of mammographic and emission images during a single breast compression. There is automatic coregistration of images from both modalities, and these results can be successfully correlated with histopathologic findings. The potential utility of functional images correlated to anatomic images would include noninvasively detecting clinically and radiographically occult cancers, assessing response to therapy, discriminating between benign and malignant breast masses, and ultimately reducing the number of invasive and costly surgical interventions. A spot-digital mammogram and subsequent PEM image, collected over a 4-minute period, were obtained in a single patient with the breast in compression after intravenous injection of (F-18)-2-deoxy-2-fluoro-D-glucose (FDG) at the time of stereotactic biopsy. The authors conclude that FDG-based lesion localization information may be combined with the lesion X-ray attenuation characteristics using this common imaging platform.

Positron emission tomography is superior to computed tomography scanning for response-assessment after radical radiotherapy or chemoradiotherapy in patients with non-small-cell lung cancer

PURPOSE

To prospectively study the capacity of positron emission tomography (PET) and computed tomography (CT) to determine response soon after radical radiotherapy or chemoradiotherapy and, thereby, predict survival. PET is known to provide a more accurate estimate of true extent of disease than CT when used to stage non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Seventy-three patients with NSCLC underwent [(18)F]fluorodeoxyglucose PET and CT scans before and after radical radiotherapy (n = 10) or chemoradiotherapy (n = 63). Follow-up PET scans were performed at a median of 70 days after radiotherapy. The median PET-CT interval was 1 day. Each patient had determinations of response to therapy made with PET and CT, categorized as complete response, partial response, no response, progressive disease, or nonassessable. Responses were correlated with subsequent survival.

RESULTS

Median survival after follow-up PET was 24 months. There was poor agreement between PET and CT responses (weighted kappa = 0.35), which were identical in only 40% of patients. There were significantly more complete responders on PET (n = 34) than CT (n = 10), whereas fewer patients were judged to be nonresponders (12 patients on PET v 20 on CT) or nonassessable (zero patients on PET v six on CT) by PET. Both CT and PET responses were individually significantly associated with survival duration; but on multifactor analysis that included the known prognostic factors of CT response, performance status, weight loss, and stage, only PET response was significantly associated with survival duration (P <.0001).

CONCLUSION

In NSCLC, a single, early, posttreatment PET scan is a better predictor of survival than CT response, stage, or pretreatment performance status.

[18F]-Fluorodeoxyglucose positron emission tomography in patients with suspected recurrence of breast cancer

AIM

To evaluate the role of [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) in patients presenting with a suspicion of breast cancer relapse after primary treatment.

MATERIALS AND METHODS

Sixty consecutive female patients with clinical (n=35) or radiological (n=25) suspicion of breast cancer recurrence were evaluated by FDG-PET. Positive PET findings were further evaluated by histological examination or clinical and radiological follow-up. In 25 patients, the serum tumor marker (CA 15-3) status was compared to the PET results.

RESULTS

Disease relapse was proven in 40 patients. Additionally, in three patients a second cancer was diagnosed with (n=1), and without (n=2) concomitant disease relapse. PET missed local recurrence in three patients, and was false positive in another four. In patient-based analysis, the overall sensitivity, specificity, and accuracy were 89%, 84%, and 87%, and 100%, 97%, and 98% for locoregional recurrence and distant metastases, respectively. FDG-PET was more sensitive than the serum tumor marker CA 15-3 in detecting relapsed breast cancer.

CONCLUSION

FDG-PET is a valuable tool in the follow-up of patients with breast cancer.

Dietary energy restriction in breast cancer prevention

Dietary energy restriction (DER) inhibits the development of spontaneous, chemically, genetically, and virally induced mammary cancer in rats and/or mice. DER inhibits the initiation and postinitiation stages of mammary carcinogenesis and the development of both ovarian-hormone-dependent and -independent mammary carcinomas. The predominant effect of DER appears to be suppression of the clonal expansion of transformed cells, and this effect is most likely mediated via the coordinated regulation of cell proliferation, apoptosis, and angiogenesis. The effects of DER on cell cycle regulation and apoptosis are consistent with the limitation of one or more cell survival factors. Evidence is presented that the chemical mediators of this effect, glucocorticoids, insulin, and/or insulin-like growth factors, are elicited in response to the limitation in glucose availability imposed by DER. Investigation of DER is highly relevant to the misregulation of body weight which has been identified as a human health problem of global proportion. Mechanistic studies hold the promise of leading to the identification of DER mimetic approaches that can be used in the prevention and control of breast cancer.

Overview of breast imaging

In summary, it is an exciting time in breast imaging with many tools being brought to bear on an ever more common problem. The challenge for this decade will be to develop optimal cost-effective strategies to use all the tools now available with minimal discomfort and disfigurement to the patient.