Accuracy of 18F-FDG PET/CT for primary tumor visualization and staging in T1 breast cancer

Role of 18F-FDG PET/CT in evaluation of recently diagnosed breast cancer patients

Background

Breast cancer is the most frequent malignant disease in women and usually affects people of all ages, races, socioeconomic classes, and geographic locations. Once breast cancer is diagnosed, tumor staging should be assessed precisely before treatment and prognosis could be determined. The purpose of this study was to determine the diagnostic usefulness of PET/CT in the initial assessment of patients with newly diagnosed breast cancer who were referred for tumor staging, pre-therapeutic or preoperative evaluation.

Results

In the examined 50 patients, PET/CT has higher sensitivity and accuracy compared to CT alone (reaching 100% for PET/CT and 96% for CT) in detecting malignant breast lesions, regional and distant nodal deposits as well as distant deposits, with subsequent upstaging in two patients.

Conclusions

18F-FDG PET/CT is a single valuable technique that detects metastatic illness in newly diagnosed breast cancer patients in an efficient, accurate, and noninvasive manner, resulting in modification of the initial staging, which in turn reflected on the patients' therapeutic plans.

ACR Appropriateness Criteria® Imaging of the Axilla

This publication reviews the current evidence supporting the imaging approach of the axilla in various scenarios with broad differential diagnosis ranging from inflammatory to malignant etiologies. Controversies on the management of axillary adenopathy results in disagreement on the appropriate axillary imaging tests. Ultrasound is often the appropriate initial imaging test in several clinical scenarios. Clinical information (such as age, physical examinations, risk factors) and concurrent complete breast evaluation with mammogram, tomosynthesis, or MRI impact the type of initial imaging test for the axilla. Several impactful clinical trials demonstrated that selected patient's population can received sentinel lymph node biopsy instead of axillary lymph node dissection with similar overall survival, and axillary lymph node dissection is a safe alternative as the nodal staging procedure for clinically node negative patients or even for some node positive patients with limited nodal tumor burden. This approach is not universally accepted, which adversely affect the type of imaging tests considered appropriate for axilla. This document is focused on the initial imaging of the axilla in various scenarios, with the understanding that concurrent or subsequent additional tests may also be performed for the breast. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Sensitivity, Specificity and the Diagnostic Accuracy of PET/CT for Axillary Staging in Patients With Stage I-III Cancer: A Systematic Review of The Literature

BACKGROUND/AIM

Axillary lymph node (ALN) status plays a key role in the staging of breast cancer. Positron Emission Tomography/Computed Tomography (PET/CT) using 18-Fluorodeoxyglucose (¹⁸FDG) can visualise ALN metastasis. However, its utility compared to current methods is unclear. We systematically reviewed the role of ¹⁸FDG PET/CT in breast cancer staging.

MATERIALS AND METHODS

PubMed, Ovid and Cochrane were searched systematically up until August 2020. Included papers had true positive (TP), false positive (FP), true negative (TN) and false negative (FN) rates, sensitivity, specificity, accuracy, positive (PPV) and negative predictive value (NPV).

RESULTS

Nine studies (n=1486) were included, showing: i) sensitivity=52.2%, ii) specificity=91.6%, iii) PPV=77.8%, iv) NPV=77.2, and v) accuracy=77.3%.

CONCLUSION

¹⁸FDG-PET/CT has a low sensitivity but high specificity for ALN disease. Therefore, ultrasound-guided biopsy could be considered in a positive CT/PET. Modest accuracy prohibits the use of ¹⁸FDG-PET/CT alone in axillary staging. Prospective research using standardised protocols and quantitative cut-off points is warranted.

Impact of 18F-FDG PET, PET/CT, and PET/MRI on Staging and Management as an Initial Staging Modality in Breast Cancer: A Systematic Review and Meta-analysis

OBJECTIVES

We performed a systematic review and meta-analysis to evaluate the impact of 18F-FDG PET, PET/CT, and PET/MRI on staging and management during the initial staging of breast cancer.

METHODS

We searched the PubMed, Embase, Cochrane Library, and KoreaMed databases until March 2020 to identify studies that reported the proportion of breast cancer patients whose clinical stage or management were changed after PET scans. The proportion of changes was pooled using a random-effects model. Subgroup and metaregression analyses were performed to explore heterogeneity.

RESULTS

We included 29 studies (4276 patients). The pooled proportions of changes in stage and management were 25% (95% confidence interval [CI], 21%-30%) and 18% (95% CI, 14%-23%), respectively. When stage changes were stratified according to initial stage, the pooled proportions were 11% (95% CI, 3%-22%) in stage I, 20% (95% CI, 16%-24%) in stage II, and 34% (95% CI, 27%-42%) in stage III. The relative proportions of intermodality and intention-to-treat changes were 74% and 70%, respectively. Using metaregression analyses, the mean age and the proportion of initial stage III to IV and histologic grade II to III were significant factors affecting the heterogeneity in changes in stage or management.

CONCLUSIONS

Currently available literature suggests that the use of 18F-FDG PET, PET/CT, or PET/MRI leads to significant modification of staging and treatment in newly diagnosed breast cancer patients. Therefore, there may be a role for routine clinical use of PET imaging for the initial staging of breast cancer.

Impact of 18F-FDG PET/MR on therapeutic management in high risk primary breast cancer patients - A prospective evaluation of staging algorithms

PURPOSE

To investigate whether potential differences in staging between a traditional staging imaging algorithm and ¹⁸F-FDG PET/MR lead to a change in patient management in breast carcinoma and to compare the diagnostic accuracy between the traditional staging algorithm and ¹⁸F-FDG PET/MR for the TNM classification.

METHOD

In this prospective cohort study from two university hospitals 56 women with newly diagnosed, therapy-naive breast cancer and increased pre-test probability for distant metastases were included. All patients were examined by a traditional staging imaging algorithm (X-ray mammography, breast ultrasonography, chest plain radiography, bone scintigraphy, and ultrasonography of the liver and axillary fossa) and whole-body ¹⁸F-FDG PET/MR including dedicated ¹⁸F-FDG PET/MR breast examinations. Each patient was discussed two times in a separate tumor board session to determine a total of three therapy recommendations based on histopathological data of the primary tumor and (1) traditional algorithm only, (2) traditional algorithm and ¹⁸F-FDG PET/MR, and (3) ¹⁸F-FDG PET/MR only. Major changes in therapy recommendations and differences between the traditional staging algorithm and ¹⁸F-FDG PET/MR for the TNM classification were evaluated.

RESULTS

Staging by ¹⁸F-FDG PET/MR led to a difference in treatment compared the traditional staging algorithm in 8/56 cases (14%). Therapy changes included therapy of the breast, locoregional nodes and systemic therapy. A trend to staging superiority was found for ¹⁸F-FDG PET/MRI without statistical significance (p = 0.3827).

CONCLUSION

In conclusion, for breast cancer patients with elevated pre-test probability for distant metastases a change of the therapy regiment occurs in 14 % of patients when staged by ¹⁸F-FDG PET/MR and confirmed by histopathology compared to a traditional staging algorithm. In particular with regard to the amendment of the guideline further assessment of ¹⁸F-FDG-PET/MR in this setting is necessary to assess the true value of this modality.

FDG PET Hybrid Imaging

Molecular imaging with positron emission tomography (PET) using tumour-seeking radiopharmaceuticals has gained wide acceptance in oncology with many clinical applications. The hybrid imaging modality PET/CT (computed tomography) allows assessing molecular as well as morphologic information at the same time. Therefore, PET/CT represents an efficient tool for whole-body staging and re-staging within one imaging modality. In oncology, the glucose analogue 18-F-fluorodeoxyglucose (FDG) is the most widely used PET/CT radiopharmaceutical in clinical routine. FDG PET and FDG PET/CT have been used for staging and re-staging of tumour patients in numerous studies. This chapter will discuss the use and the main indications of FDG PET/CT in oncology with special emphasis on lung cancer, lymphoma, head and neck cancer, melanoma and breast cancer (among other tumour entities). A review of the current literature is given with respect to primary diagnosis, staging and diagnosis of recurrent disease. Besides its integral role in diagnosis, staging and re-staging of disease in oncology, there is increasing evidence that FDG PET/CT can be used for therapy response assessment (possibly influencing therapeutic management and treatment planning) by evaluating tumour control, which will also be discussed in this chapter.

Multiparametric 18F-FDG PET/MRI of the Breast: Are There Differences in Imaging Biomarkers of Contralateral Healthy Tissue Between Patients With and Without Breast Cancer?

The rationale was to assess whether there are differences in multiparametric 18F-FDG PET/MRI biomarkers of contralateral healthy breast tissue in patients with benign and malignant breast tumors. Methods: In this institutional review board-approved prospective single-institution study, 141 women with imaging abnormalities on mammography or sonography (BI-RADS 4/5) underwent combined 18F-FDG PET/MRI of the breast at 3T with dynamic contrast-enhanced MRI, diffusion-weighted imaging, and the radiotracer 18F-FDG. In all patients, the following imaging biomarkers were recorded for the contralateral (tumor-free) breast: breast parenchymal uptake (BPU) (from 18F-FDG PET), mean apparent diffusion coefficient (from diffusion-weighted imaging), background parenchymal enhancement (BPE), and amount of fibroglandular tissue (FGT) (from MRI). Appropriate statistical tests were used to assess differences in 18F-FDG PET/MRI biomarkers between patients with benign and malignant lesions. Results: There were 100 malignant and 41 benign lesions. BPE was minimal in 61 patients, mild in 56, moderate in 19, and marked in 5. BPE differed significantly (P < 0.001) between patients with benign and malignant lesions, with patients with cancer demonstrating decreased BPE in the contralateral tumor-free breast. FGT approached but did not reach significance (P = 0.055). BPU was 1.5 for patients with minimal BPE, 1.9 for mild BPE, 2.2 for moderate BPE, and 1.9 for marked BPE. BPU differed significantly between patients with benign lesions (mean, 1.9) and patients with malignant lesions (mean, 1.8) (P < 0.001). Mean apparent diffusion coefficient did not differ between groups (P = 0.19). Conclusion: Differences in multiparametric 18F-FDG PET/MRI biomarkers, obtained from contralateral tumor-free breast tissue, exist between patients with benign and patients with malignant breast tumors. Contralateral BPE, BPU, and FGT are decreased in breast cancer patients and may potentially serve as imaging biomarkers for the presence of malignancy.

Local and whole-body staging in patients with primary breast cancer: a comparison of one-step to two-step staging utilizing 18F-FDG-PET/MRI

OBJECTIVES

The purpose of this study was to compare the diagnostic value of a one-step to a two-step staging algorithm utilizing ¹⁸F-FDG PET/MRI in breast cancer patients.

METHODS

A total of 38 patients (37 females and one male, mean age 57 ± 10 years; range 31-78 years) with newly diagnosed, histopathologically proven breast cancer were prospectively enrolled in this trial. All PET/MRI examinations were assessed for local tumor burden and metastatic spread in two separate reading sessions: (1) One-step algorithm comprising supine whole-body ¹⁸F-FDG PET/MRI, and (2) Two-step algorithm comprising a dedicated prone ¹⁸F-FDG breast PET/MRI and supine whole-body ¹⁸F-FDG PET/MRI.

RESULTS

On a patient based analysis the two-step algorithm correctly identified 37 out of 38 patients with breast carcinoma (97%), while five patients were missed by the one-step ¹⁸F-FDG PET/MRI algorithm (33/38; 87% correct identification). On a lesion-based analysis 56 breast cancer lesions were detected in the two-step algorithm and 44 breast cancer lesions could be correctly identified in the one-step ¹⁸F-FDG PET/MRI (79%), resulting in statistically significant differences between the two algorithms (p = 0.0015). For axillary lymph node evaluation sensitivity, specificity and accuracy was 93%, 95 and 94%, respectively. Furthermore, distant metastases could be detected in seven patients in both algorithms.

CONCLUSION

The results demonstrate the necessity and superiority of a two-step ¹⁸F-FDG PET/MRI algorithm, comprising dedicated prone breast imaging and supine whole-body imaging, when compared to the one-step algorithm for local and whole-body staging in breast cancer patients.

18F-FDG PET/CT in breast cancer: Evidence-based recommendations in initial staging

Current guidelines do not systematically recommend 18F-FDG PET/CT for breast cancer staging; and the recommendations and level of evidence supporting its use in different groups of patients vary among guidelines. This review summarizes the evidence about the role of 18F-FDG PET/CT in breast cancer staging and the therapeutic and prognostic impact accumulated in the last decade. Other related aspects, such as the association of metabolic information with biology and prognosis are considered and evidence-based recommendations for the use of 18F-FDG PET/CT in breast cancer staging are offered. We systematically searched MEDLINE for articles reporting studies with at least 30 patients related to clinical questions following the Problem/Population, Intervention, Comparison, and Outcome framework. We critically reviewed the selected articles and elaborated evidence tables structuring the summarized information into methodology, results, and limitations. The level of evidence and the grades of recommendation for the use of 18F-FDG PET/CT in different contexts are summarized. Level III evidence supports the use of 18F-FDG PET/CT for initial staging in patients with recently diagnosed breast cancer; the diagnostic and therapeutic impact of the 18F-FDG PET/CT findings is sufficient for a weak recommendation in this population. In patients with locally advanced breast cancer, level II evidence supports the use of 18F-FDG PET/CT for initial staging; the diagnostic and therapeutic impact of the 18F-FDG PET/CT findings is sufficient for a strong recommendation in this population. In patients with recently diagnosed breast cancer, the metabolic information from baseline 18F-FDG PET/CT is associated with tumor biology and has prognostic implications, supported by level II evidence. In conclusion, 18F-FDG PET/CT is not recommended for staging all patients with early breast cancer, although evidence of improved regional and systemic staging supports its use in locally advanced breast cancer. Baseline tumor glycolytic activity is associated with tumor biology and prognosis.

Preoperative [18]fluorodeoxyglucose-positron emission tomography/computed tomography in early stage breast cancer: Rates of distant metastases

AIM

To investigate rates of distant metastases (DM) detected with [18]fluorodeoxyglucose-positron emission tomography/computed tomography (18FDG-PET/CT) in early stage invasive breast cancer.

METHODS

We searched the English language literature databases of PubMed, EMBASE, ISI Web of Knowledge, Web of Science and Google Scholar, for publications on DM detected in patients who had 18FDG-PET/CT scans as part of the staging for early stages of breast cancer (stage I and II), prior to or immediately following surgery. Reports published between 2011 and 2017 were considered. The systematic review was conducted according to the PRISMA guidelines.

RESULTS

Among the 18 total studies included in the analysis, the risk of DM ranged from 0% to 8.3% and 0% to 12.9% for stage I and II invasive breast cancer, respectively. Among the patients with clinical stage II, the rate of occult metastases diagnosed by 18FDG-PET/CT was 7.2% (range, 0%-19.6%) for stage IIA and 15.8% (range, 0%-40.8%) for stage IIB. In young patients (< 40-year-old), 18FDG-PET/CT demonstrated a higher prevalence of DM at the time of diagnosis for those with aggressive histology (i.e., triple-negative receptors and poorly differentiated grade).

CONCLUSION

Young patients with poorly differentiated tumors and stage IIB triple-negative breast cancer may benefit from 18FDG-PET/CT at initial staging to detect occult DM prior to surgery.

Additional Prone 18F-FDG PET/CT Acquisition to Improve the Visualization of the Primary Tumor and Regional Lymph Node Metastases in Stage II/III Breast Cancer

PURPOSE

To prospectively compare prone and supine acquired 18F-FDG PET/CT for visualization of primary tumors and regional lymph nodes in stage II/III breast cancer patients.

MATERIALS AND METHODS

One hundred ninety-eight patients were included consecutively from August 2010 to April 2012. One hour after administration of 180-240 MBq 18F-FDG, PET/CT images of the thorax were firstly acquired in prone position. Subsequently, a standard PET/CT in supine position from skull base to thighs was made. Both sets of images were tested in a univariate and a multivariate analysis for the number of lesions per breast or lymph node (LN) region and anatomical mismatch between PET and CT images.

RESULTS

Images in prone position showed less compression of breast tissue, more primary tumor (PT) multifocality (P < 0.001) and more avid axillary LNs (P < 0.001) compared with supine position. Anatomical mismatch of the axillary LN metastases was found more often on supine PET/CT images compared with prone (P = 0.004). Prone images showed a smaller PT functional volume compared with supine position (P < 0.001).

CONCLUSIONS

Prone position PET/CT improved the visualization of PT multifocality and the number of detected axillary lymph nodes. Therefore, it is a valuable addition to standard supine PET/CT in the protocol for locoregional assessment in stage II/III breast cancer patients.

Quantitative Assessment of Breast Parenchymal Uptake on 18F-FDG PET/CT: Correlation with Age, Background Parenchymal Enhancement, and Amount of Fibroglandular Tissue on MRI

Background parenchymal enhancement (BPE), and the amount of fibroglandular tissue (FGT) assessed with MRI have been implicated as sensitive imaging biomarkers for breast cancer. The purpose of this study was to quantitatively assess breast parenchymal uptake (BPU) on ¹⁸F-FDG PET/CT as another valuable imaging biomarker and examine its correlation with BPE, FGT, and age.

METHODS

This study included 129 patients with suspected breast cancer and normal imaging findings in one breast (BI-RADS 1), whose cases were retrospectively analyzed. All patients underwent prone ¹⁸F-FDG PET/CT and 3-T contrast-enhanced MRI of the breast. In all patients, interpreter 1 assessed BPU quantitatively using SUV_max Interpreters 1 and 2 assessed amount of FGT and BPE in the normal contralateral breast by subjective visual estimation, as recommended by BI-RADS. Interpreter 1 reassessed all cases and repeated the BPU measurements. Statistical tests were used to assess correlations between BPU, BPE, FGT, and age, as well as inter- and intrainterpreter agreement.

RESULTS

BPU on ¹⁸F-FDG PET/CT varied among patients. The mean BPU SUV_max ± SD was 1.57 ± 0.6 for patients with minimal BPE, 1.93 ± 0.6 for mild BPE, 2.42 ± 0.5 for moderate BPE, and 1.45 ± 0.3 for marked BPE. There were significant (P < 0.001) moderate to strong correlations among BPU, BPE, and FGT. BPU directly correlated with both BPE and FGT on MRI. Patient age showed a moderate to strong indirect correlation with all 3 imaging-derived tissue biomarkers. The coefficient of variation for quantitative BPU measurements with SUV_max was 5.6%, indicating a high reproducibility. Interinterpreter and intrainterpreter agreement for BPE and FGT was almost perfect, with a κ-value of 0.860 and 0.822, respectively.

CONCLUSION

The results of our study demonstrate that BPU varied among patients. BPU directly correlated with both BPE and FGT on MRI, and BPU measurements were highly reproducible. Patient age showed a strong inverse correlation with all 3 imaging-derived tissue biomarkers. These findings indicate that BPU may serve as a sensitive imaging biomarker for breast cancer prediction, prognosis, and risk assessment.

Evaluation of a Hanging-Breast PET System for Primary Tumor Visualization in Patients With Stage I-III Breast Cancer: Comparison With Standard PET/CT

OBJECTIVE

The purposes of this study were to evaluate the performance of a mammography with molecular imaging PET (MAMMI-PET) system for breast imaging in the hanging-breast position for the visualization of primary breast cancer lesions and to compare this method with whole-body PET/CT.

SUBJECTS AND METHODS

Between March 2011 and March 2014, a prospective evaluation included women with one or more histologically confirmed primary breast cancer lesions (index lesions). After injection of 180-240 MBq of (18)F-FDG, whole-body PET/CT and MAMMI-PET acquisitions were performed, index lesions were scored 0, 1, or 2 for FDG uptake relative to background. Detection and FDG uptake were compared by breast length, maximal tumor diameter, affected breast quadrants, tumor grade, and histologic and immunologic sub-types. Finally, the two PET modalities were compared for detection of index lesions.

RESULTS

For 234 index lesions (diameter, 5-170 mm), the overall sensitivity was 88.9% for MAMMI-PET and 91% for PET/CT (p = 0.61). Twenty-three (9.8%) index lesions located too close to the pectoral muscle were missed with MAMMI-PET, and 20 index lesions were missed with PET/CT. Lesion visibility on MAMMI-PET images was influenced by tumor grade (p = 0.034) but not by cancer subtype (p = 0.65).

CONCLUSION

Although in an overall evaluation MAMMI-PET was not superior to PET/CT, MAMMI-PET does have higher sensitivity for primary breast cancer lesions within the scanning range of the device. Optimization of the positioning device may increase visualization of the most dorsal lesions.

Positron Emission Tomography/Magnetic Resonance Imaging for Local Tumor Staging in Patients With Primary Breast Cancer: A Comparison With Positron Emission Tomography/Computed Tomography and Magnetic Resonance Imaging

OBJECTIVES

This study aimed to assess the diagnostic performance of integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) of the breast for lesion detection and local tumor staging of patients with primary breast cancer in comparison to PET/computed tomography (CT) and MRI.

MATERIALS AND METHODS

The study was approved by the local institutional review board. Forty-nine patients with biopsy-proven invasive breast cancer were prospectively enrolled in our study. All patients underwent a PET/CT, and subsequently, a contrast-enhanced PET/MRI of the breast after written informed consent was obtained before each examination. Two radiologists independently evaluated the corresponding data sets (PET/CT, PET/MRI, and MRI) and were instructed to identify primary tumors lesions as well as multifocal/multicentric and bilateral disease. Furthermore, the occurrence of lymph node metastases was assessed, and the T-stage for each patient was determined. Histopathological verification of the local tumor extent and the axillary lymph node status was available for 30 of 49 and 48 of 49 patients, respectively. For the remaining patients, a consensus characterization was performed for the determination of the T-stage and nodal status, taking into account the results of clinical staging, PET/CT, and PET/MRI examinations. Statistical analysis was performed to test for differences in diagnostic performance between the different imaging procedures. P values less than 0.05 were considered to be statistically significant.

RESULTS

Positron emission tomography/MRI and MRI correctly identified 47 (96%) of the 49 patients with primary breast cancer, whereas PET/CT enabled detection of 46 (94%) of 49 breast cancer patients and missed a synchronous carcinoma in the contralateral breast in 1 patient. In a lesion-by-lesion analysis, no significant differences could be obtained between the 3 imaging procedures for the identification of primary breast cancer lesions (P > 0.05). Positron emission tomography/MRI and MRI allowed for a correct identification of multifocal/multicentric disease in 3 additional patients if compared with PET/CT. For the definition of the correct T-stage, PET/MRI and MRI showed identical results and were correct in significantly more cases than PET/CT (PET/MRI and MRI, 82%; PET/CT, 68%; P < 0.05). Furthermore, the calculated sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for the detection of nodal positive patients (n = 18) were 78%, 94%, 88%, 88%, and 88% for PET/CT; 67%, 87%, 75%, 82%, and 80% for MRI; and 78%, 90%, 82%, 88%, and 86% for PET/MRI, respectively. Differences between the imaging modalities were not statistically significant (P > 0.05).

CONCLUSIONS

Integrated PET/MRI does not provide diagnostic advantages for local tumor staging of breast cancer patients in comparison to MRI alone. Positron emission tomography/MRI and MRI enable an improved determination of the local tumor extent in comparison to PET/CT, whereas all 3 imaging modalities offer a comparable diagnostic performance for the identification of axillary disease.

PET Imaging of Breast Cancer: Role in Patient Management

Breast cancer is the most common malignancy in females. Imaging plays a critical role in diagnosis, staging and surveillance, and management of disease. Fluorodeoxyglucose (FDG) PET the imaging is indicated in specific clinical setting. Sensitivity of detection depends on tumor histology and size. Whole body FDG PET can change staging and management. In recurrent disease, distant metastasis can be detected. FDG PET imaging has prognostic and predictive value. PET/MR is evolving rapidly and may play a role management, assessment of metastatic lesions, and treatment monitoring. This review discusses current PET modalities, focusing on of FDG PET imaging and novel tracers.

Variations in (18)F-FDG uptake in breast cancer depending on PET/CT acquisition position

AIM

To evaluate the variability of quantitative 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET) combined with computed tomography (CT) parameters depending on acquisition position in a dual-position protocol for breast cancers.

MATERIALS AND METHODS

For initial staging work-up, whole-body PET/CT was first acquired in a supine position, and then followed by a regional breast scan in a prone position. The maximum standardised uptake value (SUVmax), metabolic tumour volume (MTV), and total lesion glycolysis (TLG) were measured on both acquisition positions. MTV50 and TLG50 were calculated with a threshold set to be 50% of SUVmax, and MTV2.5 and TLG2.5 with a fixed SUV threshold of 2.5.

RESULTS

The median SUVmax of breast cancers measured on the supine scans was 4.88, and 4.49 on the prone images (p<0.05). MTV and TLG also yielded significantly lower values from supine images. Regarding the tendency for the acquisition position to yield different results, a significant disagreement was observed between SUVmax and MTV50 and between SUVmax and TLG50 (kappa = -0156 and -0.001, respectively), while MTV2.5 and TLG2.5 showed a fair to moderate agreement with SUVmax (kappa = 0.311 and 0.416, respectively).

CONCLUSIONS

SUVmax, MTV, and TLG yielded lower values when acquired in the prone position compared to in the supine position. This observation could be due to the partial volume effect. When using 50% of SUVmax as a threshold, there was a significant discordance between SUVmax and volumetric parameters. Thus, acquisition position may affect quantitative PET/CT parameters and the clinical implications.

Simultaneous positron emission tomography/magnetic resonance imaging for whole-body staging in patients with recurrent gynecological malignancies of the pelvis: a comparison to whole-body magnetic resonance imaging alone

OBJECTIVES

The objective of this study was to assess the diagnostic value of integrated positron emission tomography/magnetic resonance imaging (PET/MRI) for whole-body staging of patients with recurrent gynecological pelvic malignancies, in comparison to whole-body MRI alone.

MATERIALS AND METHODS

The study was approved by the local institutional ethics committee. Written informed consent was obtained before each examination. Thirty-four consecutive patients with a suspected recurrence of cervical (n = 18) or ovarian (n = 16) cancer were prospectively enrolled for an integrated PET/MRI examination, which comprised a diagnostic, contrast-enhanced whole-body MRI protocol including dedicated sagittal dynamic imaging of the pelvis. Two radiologists separately evaluated the data sets regarding lesion count, lesion detection, lesion characterization, and diagnostic confidence. Mean and median values were calculated for each rating. Statistical analyses were performed both per-patient and per-lesion bases using a Wilcoxon signed-rank test to indicate potential significant differences among PET/MRI and MRI (alone) data sets.

RESULTS

Malignant lesions were present in 25 of the 34 patients. Positron emission tomography/magnetic resonance imaging offered correct and superior identification of all 25 patients with cancer recurrence, compared with MRI alone (23/25). A total of 118 lesions (malignant, 89; benign, 29) were detected. Positron emission tomography/magnetic resonance imaging correctly identified 88 (98.9%) of 89 malignant lesions, whereas MRI alone allowed for correct identification of 79 (88.8%) of the 89 malignant lesions. In addition, PET/MRI provided significantly higher lesion contrast and diagnostic confidence in the detection of malignant lesions (P < 0.001) compared with MRI alone.

CONCLUSIONS

These first results demonstrate the high diagnostic potential of integrated PET/MRI for the assessment of recurrence of female pelvic malignancies compared with MRI alone.

Sarcoidosis mimicking metastatic breast cancer in a patient with early-stage breast cancer

Sarcoidosis is a systemic granulomatous disorder of unknown origin that affects the lungs and mediastinal lymph nodes in most patients. The coexistence of sarcoidosis and breast cancer has been reported. An unfortunate consequence of the presence of both entities in the same patient is the risk of misdiagnosis. We report the case of a 70-year-old female with T1N0 cancer of the right breast that was initially diagnosed as stage IV because of mediastinal positron-emission tomography -positive lymphadenopathy. Biopsy of a mediastinal lymph node allowed us to diagnose sarcoidosis and correctly stage her disease as stage I breast cancer.

Diagnostic accuracy of (18)F-FDG PET/CT compared with that of contrast-enhanced MRI of the breast at 3 T

PURPOSE

To compare the diagnostic accuracy of prone (18)F-FDG PET/CT with that of contrast-enhanced MRI (CE-MRI) at 3 T in suspicious breast lesions. To evaluate the influence of tumour size on diagnostic accuracy and the use of maximum standardized uptake value (SUVMAX) thresholds to differentiate malignant from benign breast lesions.

METHODS

A total of 172 consecutive patients with an imaging abnormality were included in this IRB-approved prospective study. All patients underwent (18)F-FDG PET/CT and CE-MRI of the breast at 3 T in the prone position. Two reader teams independently evaluated the likelihood of malignancy as determined by (18)F-FDG PET/CT and CE-MRI independently. (18)F-FDG PET/CT data were qualitatively evaluated by visual interpretation. Quantitative assessment was performed by calculation of SUVMAX. Sensitivity, specificity, diagnostic accuracy, area under the curve and interreader agreement were calculated for all lesions and for lesions <10 mm. Histopathology was used as the standard of reference.

RESULTS

There were 132 malignant and 40 benign lesions; 23 lesions (13.4%) were <10 mm. Both (18)F-FDG PET/CT and CE-MRI achieved an overall diagnostic accuracy of 93%. There were no significant differences in sensitivity (p = 0.125), specificity (p = 0.344) or diagnostic accuracy (p = 1). For lesions <10 mm, diagnostic accuracy deteriorated to 91% with both (18)F-FDG PET/CT and CE-MRI. Although no significant difference was found for lesions <10 mm, CE-MRI at 3 T seemed to be more sensitive but less specific than (18)F-FDG PET/CT. Interreader agreement was excellent (κ = 0.85 and κ = 0.92). SUVMAX threshold was not helpful in differentiating benign from malignant lesions.

CONCLUSION

(18)F-FDG PET/CT and CE-MRI at 3 T showed equal diagnostic accuracies in breast cancer diagnosis. For lesions <10 mm, diagnostic accuracy deteriorated, but was equal for (18)F-FDG PET/CT and CE-MRI at 3 T. For lesions <10 mm, CE-MRI at 3 T seemed to be more sensitive but less specific than (18)F-FDG PET/CT. Quantitative assessment using an SUVMAX threshold for differentiating benign from malignant lesions was not helpful in breast cancer diagnosis.

Delivery-corrected imaging of fluorescently-labeled glucose reveals distinct metabolic phenotypes in murine breast cancer

When monitoring response to cancer therapy, it is important to differentiate changes in glucose tracer uptake caused by altered delivery versus a true metabolic shift. Here, we propose an optical imaging method to quantify glucose uptake and correct for in vivo delivery effects. Glucose uptake was measured using a fluorescent D-glucose derivative 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-deoxy-D-glucose (2-NBDG) in mice implanted with dorsal skin flap window chambers. Additionally, vascular oxygenation (SO₂) was calculated using only endogenous hemoglobin contrast. Results showed that the delivery factor proposed for correction, “R_D”, reported on red blood cell velocity and injected 2-NBDG dose. Delivery-corrected 2-NBDG uptake (2-NBDG₆₀/R_D) inversely correlated with blood glucose in normal tissue, indicating sensitivity to glucose demand. We further applied our method in metastatic 4T1 and nonmetastatic 4T07 murine mammary adenocarcinomas. The ratio 2-NBDG₆₀/R_D was increased in 4T1 tumors relative to 4T07 tumors yet average SO₂ was comparable, suggesting a shift toward a “Warburgian” (aerobic glycolysis) metabolism in the metastatic 4T1 line. In heterogeneous regions of both 4T1 and 4T07, 2-NBDG₆₀/R_D increased slightly but significantly as vascular oxygenation decreased, indicative of the Pasteur effect in both tumors. These data demonstrate the utility of delivery-corrected 2-NBDG and vascular oxygenation imaging for differentiating metabolic phenotypes in vivo.