Misleading FDG Uptake in Oncology Assessment: Beyond COVID-19 Vaccination-The Role of Pneumococcal Vaccination.

ABSTRACT: Here, we report the case of a 35-year-old woman who performed PET/CT 18F-FDG as an initial workup for HER2+ right breast invasive ductal carcinoma. Examination revealed multifocal breast involvement with homolateral lymph node involvement. Contralateral axillary adenopathy and diffuse splenic and osteomedullary hypermetabolism were also observed, suggesting associated lymphoma in the absence of a recent COVID-19 vaccination. Cytopuncture was discussed and finally postponed after the patient was found to have recently received a pneumococcal vaccination.

Colorectal Adenocarcinoma Mimicking Neuroendocrine Neoplasia on 18 F-FDOPA PET/CT.

ABSTRACT: We present a case of a 48-year-old woman who had previously undergone surgical resection for bladder paraganglioma. An 18 F-FDOPA PET/CT scan performed for suspected colorectal paraganglioma showed intense colorectal uptake associated with adenopathy. Histological examination did not support the presence of a neuroendocrine tumor but instead confirmed the presence of moderately differentiated colorectal adenocarcinoma. Colorectal adenocarcinoma belongs to the list of nonneuroendocrine false-positive tumors that can be detected using 18 F-FDOPA. Therefore, a morphological analysis is important. Thus, 18 F-FDOPA may be a marker for the aggressiveness of colorectal adenocarcinoma.

A False-Positive Bone Oligometastatic Prostate Cancer in 18 F-Choline PET/CT : Be Aware of Chronic Vascular Pitfalls.

ABSTRACT: We report the case of a 71-year-old man undergoing initial assessment for a high-risk group prostate adenocarcinoma. His medical history includes gastric carcinoma treated with surgery and chemotherapy. 18 F-choline PET/CT was performed for initial staging and displayed several intense foci uptake of sternum and thoracic vertebrae, suggestive of bone metastasis. Because of a chronic right jugulosubclavian confluent thrombosis related to his implantable chamber, a control was performed 3 weeks later. It showed spontaneous disappearance of those uptakes, consistent with pitfalls related to the collateral circulation induced by the chronic right subclavian vein thrombosis, despite the chronic anticoagulation.

Performance study of a 360° CZT camera for monitoring 177Lu-PSMA treatment.

BACKGROUND: The aim of this study was to investigate the quantification performance of a 360° CZT camera for 177Lu-based treatment monitoring. METHODS: Three phantoms with known 177Lu activity concentrations were acquired: (1) a uniform cylindrical phantom for calibration, (2) a NEMA IEC body phantom for analysis of different-sized spheres to optimise quantification parameters and (3) a phantom containing two large vials simulating organs at risk for tests. Four sets of reconstruction parameters were tested: (1) Scatter, (2) Scatter and Point Spread Function Recovery (PSFR), (3) PSFR only and (4) Penalised likelihood option and Scatter, varying the number of updates (iterations × subsets) with CT-based attenuation correction only. For each, activity concentration (ARC) and contrast recovery coefficients (CRC) were estimated as well as root mean square. Visualisation and quantification parameters were applied to reconstructed patient image data. RESULTS: Optimised quantification parameters were determined to be: CT-based attenuation correction, scatter correction, 12 iterations, 8 subsets and no filter. ARC, CRC and RMS results were dependant on the methodology used for calculations. Two different reconstruction parameters were recommended for visualisation and for quantification. 3D whole-body SPECT images were acquired and reconstructed for 177Lu-PSMA patients in 2-3 times faster than the time taken for a conventional gamma camera. CONCLUSION: Quantification of whole-body 3D images of patients treated with 177Lu-PSMA is feasible and an optimised set of parameters has been determined. This camera greatly reduces procedure time for whole-body SPECT.

Unintentional Intra-arterial Injection of 177Lu-PSMA-1 in a Patient With a Peritoneal Carcinosis Secondary to a Metastatic Prostate Cancer.

ABSTRACT: We report the case of an 81-year-old man presenting with peritoneal carcinosis secondary to a metastatic castrate-resistant prostate cancer addressed for 177Lu-PSMA-1 therapy. During the second cycle, a diffuse uptake in his left forearm was observed on the 1-hour postinjection scintigraphy, typical for an accidental intra-arterial injection. Less than 24 hours postinjection, a full removal of the intra-arterial injection was observed in the man, without any pain or symptoms. Moreover, the man demonstrated an 85% PSA reduction and a CT OR following the RECIST 1.1 criteria after 3 cycles.

PET metabolic tumor volume as a new prognostic factor in childhood rhabdomyosarcoma.

PURPOSE: Childhood RMS is a rare malignant disease in which evaluation of tumour spread at diagnosis is essential for therapeutic management. F-18 FDG-PET imaging is currently used for initial RMS disease staging. MATERIALS AND METHODS: This multicentre retrospective study in six French university hospitals was designed to analyse the prognostic accuracy of MTV at diagnosis for patients with RMS between 1 January 2007 and 31 October 2017, for overall (OS) and progression-free survival (PFS). MTV was defined as the sum of the primitive tumour and the largest metastasis, where relevant, with a 40% threshold of the primary tumour SUVmax. Additional aims were to define the prognostic value of SUVmax, SUVpeak, and bone lysis at diagnosis. RESULTS: Participants were 101 patients with a median age of 7.4 years (IQR [4.0-12.5], 62 boys), with localized disease (35 cases), regional nodal spread (43 cases), or distant metastases (23). 44 patients had alveolar subtypes. In a univariate analysis, a MTV greater than 200 cm3 was associated with OS (HR = 3.47 [1.79;6.74], p<0.001) and PFS (HR = 3.03 [1.51;6.07], p = 0.002). SUVmax, SUVpeak, and bone lysis also influenced OS (respectively p = 0.005, p = 0.004 and p = 0.007) and PFS (p = 0.029, p = 0.019 and p = 0.015). In a multivariate analysis, a MTV greater than 200 cm3 was associated with OS (HR = 2.642 [1.272;5.486], p = 0.009) and PFS (HR = 2.707 [1.322;5.547], p = 0.006) after adjustment for confounding factors, including SUVmax, SUVpeak, and bone lysis. CONCLUSION: A metabolic tumor volume greater than 200 cm3, SUVmax, SUVpeak, and bone lysis in the pre-treatment assessment were unfavourable for outcome.

Cholesterol Granuloma: Unusual Pitfall for Hodgkin Lymphoma Evaluation With 18F-FDG PET/CT.

ABSTRACT: Cholesterol granuloma (CG) is a foreign body-type granuloma that forms in response to cholesterol crystals. Its etiology and pathogenesis are unclear. 18F-FDG is not a tumor-specific agent. Fibroblasts, macrophages, and multinucleated giant cells also take up 18F-FDG. Like sarcoid granulomas or fibrous dysplasia, CG avidly takes up 18F-FDG and can mimic tumor involvement. We present 2 cases of histologically proven CG, which has been misinterpreted as active residual Hodgkin lymphoma lesion.

Yttrium-90 quantitative phantom study using digital photon counting PET.

BACKGROUND: PET imaging of 90Y-microsphere distribution following radioembolisation is challenging due to the count-starved statistics from the low branching ratio of e+/e- pair production during 90Y decay. PET systems using silicon photo-multipliers have shown better 90Y image quality compared to conventional photo-multiplier tubes. The main goal of the present study was to evaluate reconstruction parameters for different phantom configurations and varying listmode acquisition lengths to improve quantitative accuracy in 90Y dosimetry, using digital photon counting PET/CT. METHODS: Quantitative PET and dosimetry accuracy were evaluated using two uniform cylindrical phantoms specific for PET calibration validation. A third body phantom with a 9:1 hot sphere-to-background ratio was scanned at different activity concentrations of 90Y. Reconstructions were performed using OSEM algorithm with varying parameters. Time-of-flight and point-spread function modellings were included in all reconstructions. Absorbed dose calculations were carried out using voxel S-values convolution and were compared to reference Monte Carlo simulations. Dose-volume histograms and root-mean-square deviations were used to evaluate reconstruction parameter sets. Using listmode data, phantom and patient datasets were rebinned into various lengths of time to assess the influence of count statistics on the calculation of absorbed dose. Comparisons between the local energy deposition method and the absorbed dose calculations were performed. RESULTS: Using a 2-mm full width at half maximum post-reconstruction Gaussian filter, the dosimetric accuracy was found to be similar to that found with no filter applied but also reduced noise. Larger filter sizes should not be used. An acquisition length of more than 10 min/bed reduces image noise but has no significant impact in the quantification of phantom or patient data for the digital photon counting PET. 3 iterations with 10 subsets were found suitable for large spheres whereas 1 iteration with 30 subsets could improve dosimetry for smaller spheres. CONCLUSION: The best choice of the combination of iterations and subsets depends on the size of the spheres. However, one should be careful on this choice, depending on the imaging conditions and setup. This study can be useful in this choice for future studies for more accurate 90Y post-dosimetry using a digital photon counting PET/CT.

Second primary cancers: a retrospective analysis of real world data using the enhanced medical research engine ConSoRe in a French comprehensive cancer center.

BACKGROUND: Second primary cancers (SPC) account for 18% of all cancers. We used the enhanced medical/health data mining tool ConSoRe to search aggregated data, analyze electronic patient records (EPR), and better characterize patients with SPC. METHODS: This retrospective cohort study used ConSoRe to identify EPRs from patients with SPC referred to the regional cancer center Leon Bérard from 1993 to 2017, and examined characteristics of patients with SPC, frequencies of first primary cancer (FPC) localization in the global population of patients with SPC, and time to SPC. Data set was extracted on January 1, 2018. RESULTS: Among 296,530 EPRs, we identified 157,187 patients with FPC, including 13,002 (8%) patients with SPC. Between 2000 and 2010, the rate of SPC was 34%, and 52% of SPC were identified in the last years (2010-2017). In men, main cancers were head and neck cancer, lymphoma, and prostate carcinoma accounting for 15.6%, 12.8%, and 10.5% of FPC, while the three most common SPC were head and neck cancer (13.2%), lung cancer (11.8%) and lymphoma (9.2%). In women, breast cancers, lymphoma, and skin cancers accounted for 48.8%, 8%, and 5.1% of first cancers, and for 31.1%, 7% and 6% of SPC. CONCLUSION: The data mining tool ConSoRe contributes to access to real world data, and to better characterize patients with SPC. Expanding such approach to any comprehensive center will allow a global overview of the follow-up of patients with cancer, and help to improve long-term management and adapt surveillance.

Discordant results in 18F-FDG PET/CT and ultrasound-based assessment for axillary lymph node metastasis detection: A large retrospective analysis in 560 patients with breast cancer.

PURPOSE: Ultrasound is the recommended modality to assess axillary lymph node involvement in breast cancer; nevertheless, 18F-fluorodeoxyglucose (18F-FDG) integrated positron emission tomography/computed tomography (PET/CT) diagnostic efficiency, to identify suspicious lesions, is also considered. We aim to report discrepancies in ultrasound and 18F-FDG PET/CT results. METHODS: This single-centered retrospective analysis selected consecutive patients with invasive ductal biopsy-proven breast cancer, for whom divergent 18F-FDG PET/CT and axillary ultrasound imaging (and/or core needle biopsy if available) had been performed, and described clinical, histological, imaging, and surgery data. RESULTS: This retrospective study included 560 patients and identified discordant results between 18F-FDG PET/CT and ultrasound (suspicious 18F-FDG PET/CT and normal ultrasound imaging and/or core needle biopsy) in 20 (4%) patients. Axillary lymph node involvement was confirmed in 17 (85%) out of these 20 patients. Further, the lymph nodes were smaller than one centimeter in 12 (60%) patients, macrometastasic involvement (involvement >2 mm) was detected in 13 (65%) patients, and more than 3 macrometastases were detected in 6 (30%) patients. All patients had an aggressive breast cancer. The sentinel node biopsy performed in 9 (45%) patients allowed to reveal lymph node involvement, even in cases of macrometastatic involvement. CONCLUSION: Discordant results were issued from normal ultrasound imaging and/or core needle biopsy, and suspicious 18F-FDG PET/CT revealed that 18F-FDG PET/CT may overcome axillary ultrasound limits in the specific case of aggressive breast cancers, especially for axillary lymph nodes smaller than 1 centimeter. Sentinel node biopsy remains a valuable aid, even in patients with macrometastatic involvement.

Contribution of Different Positron Emission Tomography Tracers in Glioma Management: Focus on Glioblastoma.

Although rare, glioblastomas account for the majority of primary brain lesions, with a dreadful prognosis. Magnetic resonance imaging (MRI) is currently the imaging method providing the higher resolution. However, it does not always succeed in distinguishing recurrences from non-specific temozolomide, have been shown to improve -related changes caused by the combination of radiotherapy, chemotherapy, and targeted therapy, also called pseudoprogression. Strenuous attempts to overcome this issue is highly required for these patients with a short life expectancy for both ethical and economic reasons. Additional reliable information may be obtained from positron emission tomography (PET) imaging. The development of this technique, along with the emerging of new classes of tracers, can help in the diagnosis, prognosis, and assessment of therapies. We reviewed the current data about the commonly used tracers, such as 18F-fluorodeoxyglucose (18F-FDG) and radiolabeled amino acids, as well as different PET tracers recently investigated, to report their strengths, limitations, and relevance in glioblastoma management.

Quantitative analysis of normal and pathologic adrenal glands with 18F-FDOPA PET/CT: focus on pheochromocytomas.

INTRODUCTION: Many studies have reported the high performance of 6-fluorine-18-fluorodihydroxyphenilalanine (F-FDOPA) PET/CT in the diagnosis of pheochromocytomas but nobody seems to have investigated physiological and pathological adrenal glands from a quantitative point of view. The purpose of the present study was to assess the quantitative F-FDOPA uptake of normal and pathologic adrenal glands and to establish thresholds to characterize pheochromocytomas. We were especially interested in characterizing the remaining adrenal glands captation after an adrenalectomy. PATIENTS AND METHODS: We reviewed 112 F-FDOPA PET/CT scans taken for different indications. A total of 212 adrenal glands, of which 17 were pheochromocytomas, were analyzed on the basis of their functional and morphological features. The final diagnosis was based on histologic proof when available (six pheochromocytomas) or after synthesis of clinical, biological, morphological, and functional results. Maximum standardized uptake value (SUVmax), mediastinum, and liver ratios in case of pheochromocytomas, adenomas, and solitary adrenal glands were determined and compared with those of healthy glands. Receiver operating characteristic curves were determined and areas under the curve were compared for different cutoffs of each index. RESULTS: Pheochromocytomas demonstrated a higher F-FDOPA uptake compared with normal adrenal glands (mean SUVmax: 7.5, SD 4.0, range: 3.5-20.0 vs. mean SUVmax: 2.6, SD: 0.8, range: 1.0-6.9) (P<0.0001). An SUVmax threshold of 4.2 has a sensitivity and specificity of 94 and 98%, respectively. The areas under the curve were 0.988, 0.991, and 0.987 for an SUVmax of 4.2, a mediastinum ratio of 3.0, and a liver ratio of 1.7, respectively. A large number of nonsecreting pheochromocytomas were noticed. On the basis of the SUVmax no statistically significant difference was found between secreting (SUVmax: 8.9, SD: 5.3) and nonsecreting pheochromocytomas (SUVmax: 5.1, SD: 0.9) (P=0.141). After unilateral adrenalectomy, solitary glands presented no increased uptake compared with healthy adrenal glands. An unexpected lower captation was also observed (SUVmax: 2.0, P=0.047). CONCLUSION: We confirm the high affinity of F-FDOPA for secreting or nonsecreting pheochromocytoma. Indeed within a series of various adrenal glands, only these tumors presented a significant increased uptake compared with normal adrenal glands. Because of a high rate of nonhypersecreting lesions, F-FDOPA can act as a surrogate to biological assays. After an adrenalectomy, the remaining glands did not demonstrate compensatory accumulation of F-FDOPA. To our knowledge this last point has never been addressed.

FDOPA Patterns in Adrenal Glands: A Pictorial Essay.

F-FDOPA is a well-established tool to explore pheochromocytomas. It tends to replace I-MIBG scan in metastatic pheochromocytomas, multiple endocrine neoplasia type 2-related tumors, succinate dehydrogenase [ubiquinone] iron-sulfur subunit-negative tumors, and succinate dehydrogenase[ZERO WIDTH SPACE]-positive lesions. To our knowledge, no study has characterized physiological and pathological adrenal glands with F-FDOPA from a quantitative point of view. We report the features of different normal and pathological adrenal glands with F-FDOPA. Within our series, only pheochromocytomas present a significantly increased uptake reflecting the high specificity of this tracer. Tumors such as adenomas or myelolipomas present no F-FDOPA significant accumulation. Interestingly, adrenal gland hyperplasia and solitary glands do not demonstrate compensatory uptake.

Interest of systematic screening of pheochromocytoma in patients with neurofibromatosis type 1.

OBJECTIVE: Pheochromocytoma (PHEO) may occur in 0.1-5.7% of patients presenting with a neurofibromatosis type 1 (NF1). Current recommendations are to explore only symptomatic patients. The objective of the study is to evaluate the prevalence and the interest of a systematic PHEO screening in this population. DESIGN: A prospective study in a French tertiary center including consecutive NF1 patients older than 18 years. METHODS: A systematic screening combining abdominal imaging and urinary fractionated metanephrines was proposed. In case of positivity of one or both exams, (123)I-metaiodobenzylguanidine scintigraphy or [(18)F]-fluoro-dihydroxyphenylalanine PET imaging was performed. The diagnosis of secreting PHEO was retained in case of elevated urinary metanephrines associated with positive scintigraphy and non-secreting PHEO when urinary metanephrines were normal with a positive scintigraphy. RESULTS: Between January 2014 and August 2015, 234 patients were included and 156 patients (66.7%) completed both exams. In these 156 patients, 12 PHEOs were diagnosed, representing a prevalence of 7.7%. Of these, six PHEOs were secreting, with only two symptomatic patients. The tumor size of these PHEOs were bigger than that of non-secreting PHEO (25.2 ± 6.6 vs 14 ± 6.9 mm, P = 0.0165). One lesion was bilateral. Mean metanephrine and normetanephrine levels were 3.2 ± 2.6N and 2.8 ± 1N respectively. Three patients underwent surgery. The six patients with non-secreting PHEO were asymptomatic. One of them had bilateral lesion and one underwent surgery. CONCLUSIONS: PHEO in NF1, whether or not secreting, are mostly asymptomatic. The current strategy to explore only symptomatic patients leads to an underestimation of prevalence with the risks inherent to the existence of an unrecognized PHEO.

Diagnostic Accuracy of PET/CT-Guided Percutaneous Biopsies for Malignant Peripheral Nerve Sheath Tumors in Neurofibromatosis Type 1 Patients.

BACKGROUND: Malignant peripheral nerve sheath tumors (MPNST) are one of the most frequent causes of death in patients with neurofibromatosis type 1 (NF1). Early detection is crucial because complete surgical resection is the only curative treatment. It has been previously reported that an 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) image with a T/L (Tumor/Liver) SUV max ratio > 1.5 provides a high negative predictive value; however, it is not specific enough to make a NF1-related MPNST diagnosis. A formal proof of malignant transformation from a histological analysis is necessary before surgical excision because the procedure can cause mutilation. The objective of the present work was to investigate the effectiveness of and complications associated with PET/CT-guided percutaneous biopsies for an NF1-related MPNST diagnosis. METHODS: PET/CT-guided percutaneous biopsy procedures performed on 26 NF1 patients with a clinical suspicion of MPNST and a suspect lesion from a PET/CT scan (T/L SUV max ratio > 1.5) were retrospectively evaluated. The localization of the suspected malignant site was determined using PET/CT. A stereotactic (ultrasonic and CT control) core biopsy technique was used with a local anesthesia. RESULTS: The first PET/CT-guided percutaneous biopsies enabled a pathological diagnosis for all of the patients (no "inconclusive " results were obtained), and no secondary procedures were needed. Among the 26 patients, the histopathological results from the biopsy were malignant in 17 cases and benign (BPNST with atypical cells) in nine cases. No complications from the diagnostic procedure were observed. A surgical resection was performed in 18 patients (seven benign and 11 malignant biopsies), removing the fine needle biopsy scar. In addition, six locally advanced/metastatic MPNST were treated with chemo/radiotherapy, and two BPNST had no progression after a follow-up of 14 and 39 months, respectively. The PET/CT-guided percutaneous biopsy gave 25 accurate diagnoses and one false negative (BPNST with atypical cells on the biopsy and MPNST on the operated tumor), resulting in a diagnostic accuracy rate of 96%. This false negative case may be explained by the high heterogeneity of the tumor: benign areas were contiguous with the malignant ones and associated with inflammation. CONCLUSIONS: PET/CT-guided percutaneous biopsies are an effective and relatively non-traumatic procedure for diagnosis of NF1-related MPNST. It is the most reliable approach for early detection of MPNST.

Utility of 18F-FDG PET with a semi-quantitative index in the detection of sarcomatous transformation in patients with neurofibromatosis type 1.

BACKGROUND: Malignant peripheral nerve sheath tumors (MPNSTs) are a serious complications of neurofibromatosis type 1 associated with poor prognosis and deeper lesions can be difficult to diagnose. 18-FDG PET improves the detection of malignancies. However, the criteria for malignancy, notably the SUVmax threshold, are not standardized. Therefore, the aim of the study was to evaluate a semi-quantitative index for the reproducible detection of MPNST with FDG PET. METHODS: It is a multicenter retrospective study conducted between 2000 to 2012. All patients with NF1 referred for suspected MPNST underwent PET. Since SUVmax was not available until 2004 in our centers, we had to settle for the semi-quantitative method used at that time, the uptake ratio between the tumor and the normal liver (T/L ratio) with 1.5 as the cut-off for malignancy. When dedicated PET with SUVmax became available, the semi-quantitative analysis of PET images remained, along with SUVmax. RESULTS: 113 patients with 145 tumors were included. PET assessment revealed 65 suspected lesions with T/L >1.5 and among these, 40 were MPNSTs. 80 tumors were classified as non-suspicious, and 79 were benign. The 1.5 T/L cut-off had a negative predictive value (NPV) of 98,8% and a positive predictive value of 61,5%. The positive likelihood ratio (LR) was 4,059, the negative LR was 0,032 with 97% sensitivity and 76% specificity. CONCLUSIONS: This study, which is among the largest published, confirms the utility of PET for detecting NF1-associated MPNSTs. A semi-quantitative index, the T/L ratio with a cut-off of 1.5, allowed sensitive and specific differentiation of malignant from benign tumors better than SUVmax. When T/L was <1.5, MPNSTs were ruled out with 98,8% NPV. When T/L was >1.5, there was a strong suspicion of malignancy. This semi-quantitative analytical method is as simple as SUVmax, but is more sensitive, more reproducible and non-user-dependent.

Additional Benefit of F-18 FDG PET/CT in the staging and follow-up of pediatric rhabdomyosarcoma.

PURPOSE: The therapeutic management of rhabdomyosarcoma (RMS) is strongly dependent on initial staging. This study aimed to evaluate F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) as an adjunct to conventional imaging (CI) in the staging and follow-up of pediatric RMS. MATERIALS AND METHODS: A total of 13 consecutive children and adolescents (12 males, 1 female; mean age, 9.6 years) with histologically proven RMS (10 alveolar, 3 embryonal), in whom FDG PET/CT was performed at staging and follow-up, were retrospectively included. In total, 35 FDG PET/CT were compared with CI (MRI, CT, and bone scintigraphy) performed with a less than a 15-day interval. Histologic data, follow-up (mean, 27 months), and the final judgment of a multidisciplinary tumor board were considered as the standard of reference for result interpretation. RESULTS: At staging, FDG PET/CT revealed 1 RMS of the prostate missed by CI, and found 19 true-positive lymph node territories in 4 patients and 11 bone metastases in 3 patients, versus 12 and 3, respectively, with CI. Conversely, FDG PET/CT was less sensitive for detecting infracentimetric lung nodules in 1 patient. On the whole analysis, FDG PET/CT modified lymph node staging in 4 of 13 patients, bone involvement in 2 patients, and led to treatment alteration in 2 children. CONCLUSIONS: FDG PET/CT can be useful in staging and restaging pediatric RMS, especially for assessing lymph nodes and bone involvement, and for detecting unknown primary sites of RMS, with potential therapeutic strategy alteration.

Value of PET-FDG in primary breast cancer based on histopathological and immunohistochemical prognostic factors.

BACKGROUND: The aim of the study was to analyze in breast tumors the correlation between [(18)F]fluorodeoxyglucose (FDG) uptake assessed by positron emission tomography (PET) and histopathological and immunohistochemical prognostic factors. METHODS: FDG-PET combined with computed tomography (CT) was performed before surgery in 45 women with biopsy-proven primary breast cancer. The standardized uptake value (SUV) was compared with histopathological findings after surgery. RESULTS: A positive relationship was found between SUV and histological grade (p < 0.0001), histological type (p = 0.001), tumor size (p < 0.0435), estrogen receptor status (p < 0.0005), and progesterone receptor status (p = 0.002). FDG-PET/CT revealed unknown distant metastatic lesions in 2 of 12 patients with triple-negative breast cancer. The sensitivity of FDG-PET/CT for detecting axillary lymph node metastases was, respectively, 21% and 100% for pN1 and pN2 cases, whereas specificity was 100% for pN0. CONCLUSION: SUV, a preoperative and noninvasive metabolic parameter, correlates with other known prognostic factors in breast cancer. This study provides valuable insight into the usefulness of FDG-PET/CT for preoperative staging of patients with triple-negative and poorly differentiated breast tumors but not for evaluating axillary lymph nodes and lobular carcinomas.