Evaluation of blood supply and metabolism in tumor, axillary lymph node and normal breast tissue with F-18 FDG PET/CT in breast cancer: comparison with pathological prognostic factors.

BACKGROUND AND PURPOSE: Perfusion parameters obtained in F-18 FDG PET/CT performed for staging purposes in breast cancers may provide additional information about tumor biology as well as glucose metabolism. The aim of this study was to evaluate throughout F-18 FDG PET/CT the relationship between blood flow and glucose metabolism and histological parameters of the primary tumor, normal mammary gland, and axillary lymph nodes in breast cancer patients. MATERIALS AND METHODS: Sixty six female patients (mean age 51 y ± 12,81) were prospectively included to this study. We performed dynamic blood flow (f) study that started with 296-444 MBq (8-12 mCi) F-18 FDG injection and lasted for 10 minutes, and glucose metabolism (m) imaging one hour later. On each frame, mean activity concentration (AC) values (Bq/mL) were recorded on a spherical volume of interest (VOI) having a volume of ~ 1 cm3 on the hottest voxel of primary tumor (T), across normal breast gland (NG) and ipsilaterally axillary lymph nodes (iLN). Correlations among PET parameters and estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (c-erbB2) and Ki67 index were analyzed. RESULTS: T volume (TV) ranged from 1.1 to 85.28 cm3 [median (IR): 6.44 (11.78)]. There were positive correlations between c-erbB2 and TACf and between c-erbB2 and iLNACf (p = 0.045, r = + 0.248; p = 0.050, r = + 0.242). In the ER positive (ERP) patients, TV and TACm were significantly lower than those of ER negative (ERN) (respectively p = 0.044 and p = 0.041). In patients with two positive Ki-67 indices, iLN-SUVmax was significantly higher than one-positive patients (p = 0.020). There was a negative correlation between NGACm and histological grade of tumor (p = 0.005, r = - 0.365). CONCLUSIONS: Breast cancer shows differences in progression, metastasis and survival due to its diversity in terms of molecular, biological and angiogenesis. High glucose metabolism in breast cancers is associated with tumor aggressiveness. Being able to examine tumor tissue characteristics such as blood flow and glucose metabolism with a single diagnostic technique and to reveal its relationship with histological parameters can provide a reliable pretherapeutic evaluation in breast cancers.

The utility of F-18 FDG PET/CT for diagnosis and response evaluation of hepatosplenic tuberculosis.

A 77-year-old woman underwent F-18 FDG PET/CT for evaluation of fever focus. Diffuse and intense hepatosplenic uptake was noted and lymphoma or tuberculosis was proposed. Liver biopsy revealed chronic granulomatous inflammation with Langerhans-type giant cells and necrosis. A follow-up PET/CT after anti-tuberculosis treatment revealed that the hepatosplenic uptake had resolved.

PAGET'S DISEASE OF THE BONE FOUND INCIDENTALLY ON F-18 FDG PET/CT: CLINICAL SIGNIFICANCE AND DIFFERENTIAL DIAGNOSTIC CRITERIA.

Background: Paget Disease (PD) is usually asymptomatic and discovered incidentally, it is known that it is exhibited low to high grade increased F-18 FDG uptake. Aim: In this study, we investigated the distinguishability of FDG PET/CT in incidental PD cases from other bone diseases and at different stages of the disease. Patients and Methods: In this cross-sectional, descriptive study, "Paget" identification associated with PET/CT reports was found in 69 of 18,119 studies (~3.8%). Of the 45 patients (33 males and 12 females) eligible for inclusion in the study, 35.6% had monostotic and 64.4% had polyostotic disease (p>0.5). There was no statistically significant difference in biochemical parameters between groups. Results: According to the radiological appearance of the patients, 36 were in the mixed stage and 9 were in the blastic stage. Only the difference in ALP and creatinine values between the groups was statistically significant. SUVmax, SUVmean and HU values were found to be statistically significantly higher in pagetoid bones compared to control bone lesions. For SUVmax for PD bone lesion we found the 2.55 cutoff point with a sensitivity of 91% and a specificity of 84%. Conclusion: The specific radiological appearance of bone lesions and the evaluation of metabolic activity compared to normal bone seem to help differentiate PD from other lesions. Prospective studies are needed in the differentiation of FDG's disease stage and treatment response evaluation. The ability to differentiate between benign and malignant FDG avid bone lesions in oncological patients' enables appropriate patient management, including avoiding unnecessary additional invasive procedures such as bone biopsy.

Radiofrequency ablation for treatment of thyroid follicular neoplasm with low SUV in PET/CT study.

OBJECTIVES: To evaluate the feasibility of radiofrequency ablation (RFA) on follicular neoplasm with low standard uptake value (SUV) in a Positron emission tomography (PET/CT) study. METHODS: From January 2018 to July 2019, 86 consecutive patients were diagnosed with follicular neoplasm. Of the patients, 28 with PET/CT scans were enrolled in this study. All patients received ultrasound, fine/core needle aspiration, and PET/CT scan prior to treatment. In accordance with previous studies, we recommended 6 patients who had follicular neoplasm with SUVmax ≥5 undergo surgical resection due to an elevated suspicion of malignancy. For 22 patients SUVmax <5, RFA was performed using the moving shot technique. Ultrasound was performed 6 to 12 months after each procedure. RESULTS: Statistically significant volume reductions during follow-up between values prior to RFA and 12 months post RFA were demonstrated (12.6 ± 20.9 vs. 2.4 ± 3.0 cm3, p < 0.001). Volume reduction ratios at 6-12 months (mean: 10.1 months) after RFA were 73.3% ± 17.7%. One patient presented with vocal cord palsy and recovered within 3 months after RFA. No postprocedural hypothyroidism occurred in the RFA patients. CONCLUSIONS: By using PET/CT, we can select patients with low SUV follicular neoplasm. RFA offers a safe and feasible alternative treatment option for patients unsuitable or unwilling to undergo surgery.KEY POINTSBy using positron emission tomography-computed tomography, we can distinguish low SUV follicular neoplasm for radiofrequency ablation.For low SUV follicular neoplasm, RF ablation offers a safe and effective alternative treatment option for patients unsuitable or unwilling to undergo surgery.

Imaging of non-neurogenic peripheral nerve malignancy-a case series and systematic review.

OBJECTIVE: To evaluate the frequency, clinico-pathologic and imaging features of malignant tumors in peripheral nerves which are of non-neurogenic origin (non-neurogenic peripheral nerve malignancy-PNM). MATERIALS AND METHODS: We retrospectively reviewed our pathology database for malignant peripheral nerve tumors from 07/2014-07/2019 and performed a systematic review. Exclusion criteria were malignant peripheral nerve sheath tumor (MPNST). Clinico-pathologic and imaging features, apparent diffusion coefficient (ADCmin), and standard uptake values (SUVmax) are reported. RESULTS: After exclusion of all neurogenic tumors (benign = 196, MPNST = 57), our search yielded 19 non-neurogenic PNMs (7%, n = 19/272), due to primary intraneural malignancy (16%, n = 3/19) and secondary perineural invasion from an adjacent malignancy (16%, n = 3/19) or metastatic disease (63%, n = 12/19). Non-neurogenic PNMs were located in the lumbosacral plexus/sciatic nerves (47%, n = 9/19), brachial plexus (32%, n = 6/19), femoral nerve (5%, n = 1/19), tibial nerve (5%, n = 1/19), ulnar nerve (5%, n = 1/19), and radial nerve (5%, n = 1/19). On MRI (n = 14/19), non-neurogenic PNM tended to be small (< 5 cm, n = 10/14), isointense to muscle on T1-W (n = 14/14), hyperintense on T2-WI (n = 12/14), with enhancement (n = 12/12), low ADCmin (0.5-0.7 × 10-3 mm2/s), and variable metabolic activity (SUVmax range 2.1-13.1). A target sign was absent (n = 14/14) and fascicular sign was rarely present (n = 3/14). Systematic review revealed 89 cases of non-neurogenic PNM. CONCLUSION: Non-neurogenic PNMs account for 7% of PNT in our series and occur due to metastases and primary intraneural malignancy. Although non-neurogenic PNMs exhibit a non-specific MRI appearance, they lack typical signs of neurogenic tumors such as the target sign. Quantitative imaging features identified by DWI (low ADC) and F18-FDG PET/CT (high SUV) may be helpful clues to the diagnosis.

Complete splenic vein tumour thrombus in primary gastric malignancy on F18-fluorodeoxyglucose positron emission tomography-computed tomography.

Tumour thrombus is an uncommon complication with ominous outcomes. F18 FDG PET-CT scan helps in differentiating tumour thrombus from venous thrombus owing to its metabolic uptake similar to the tumour. We discuss an interesting case of gastric malignancy with complete splenic vein tumour thrombosis on initial presentation.

A systematic review and meta-analysis of 18F-fluoro-d-deoxyglucose positron emission tomography interpretation methods in vascular graft and endograft infection.

OBJECTIVE: Vascular graft and endograft infection (VGEI) has high morbidity and mortality rates. Diagnosis is complicated because symptoms vary and can be nonspecific. A meta-analysis identified 18F-fluoro-d-deoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) as the most valuable tool for diagnosis of VGEI and favorable to computed tomography as the current standard. However, the availability and varied use of several interpretation methods, without consensus on which interpretation method is best, complicate clinical use. The aim of this study was to evaluate the diagnostic performance of different interpretation methods of 18F-FDG PET/CT in diagnosis of VGEI. METHODS: A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data sources included PubMed/MEDLINE, Embase, and Cochrane Library. A meta-analysis was conducted on the different interpretation methods for 18F-FDG PET/CT in diagnosis of VGEI, including visual FDG uptake intensity, visual FDG uptake pattern, and quantitative maximum standardized uptake (SUVmax). RESULTS: Of 613 articles, 13 were included (10 prospective and 3 retrospective articles). The FDG uptake pattern method (I2 = 26.2%) showed negligible heterogeneity, whereas the FDG uptake intensity (I2 = 42.2%) and SUVmax (I2 = 42.1%) methods showed moderate heterogeneity. The pooled sensitivity for FDG uptake intensity was 0.90 (95% confidence interval [CI], 0.79-0.96); for uptake pattern, 0.94 (95% CI, 0.89-0.97); and for SUVmax, 0.95 (95% CI, 0.76-0.99). The pooled specificity for FDG uptake intensity was 0.59 (95% CI, 0.38-0.78); for FDG uptake pattern, 0.81 (95% CI, 0.71-0.88); and for SUVmax, 0.77 (95% CI, 0.63-0.87). The uptake pattern interpretation method demonstrated the best positive and negative post-test probability, 82% and 10%, respectively. CONCLUSIONS: This meta-analysis identified the FDG uptake pattern as the most accurate assessment method of 18F-FDG PET/CT for diagnosis of VGEI. The optimal SUVmax cutoff, depending on the vendor, demonstrated strong sensitivity and moderate specificity.

Diagnostic performance of F-18 FDG PET for detection of cardiac sarcoidosis; A systematic review and meta-analysis.

OBJECTIVE: The purpose of the current study was to investigate the diagnostic performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for diagnosis of cardiac sarcoidosis (CS) through a systematic review and meta-analysis. METHODS: The PubMed and EMBASE database, from the earliest available date of indexing through 31 March 31, 2018, were searched for studies evaluating the diagnostic performance of F-18 FDG PET or PET/CT for CS. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR-), and constructed summary receiver operating characteristic (SROC) curves. RESULTS: Across 17 studies (891 patients), the pooled sensitivity was 0.84 [95% confidence interval (95% CI) 0.71-0.91] with heterogeneity (I2 = 77.5) and a pooled specificity of 0.83 (95% CI 0.74-0.89) with heterogeneity (I2 = 80.0). Likelihood ratio (LR) syntheses gave an overall LR+ of 4.9 (95% CI 3.3-7.3) and LR- of 0.2 (95% CI 0.11-0.35). The pooled diagnostic odds ratio was 27 (95% CI 14-55). Hierarchical SROC curve indicates that the area under the curve was 0.90 (95% CI 0.87-0.92). Meta-regression showed that combined myocardial perfusion imaging was the source of heterogeneity. CONCLUSION: The current meta-analysis showed the moderate sensitivity and specificity of F-18 FDG PET or PET/CT for diagnosis of CS. The presence of combined myocardial perfusion imaging could improve diagnostic accuracy of F-18 FDG PET or PET/CT for diagnosis of CS. At present, the literature regarding the use of F-18 FDG PET for detection of CS remains limited; thus, further large multicenter studies would be necessary to substantiate the diagnostic accuracy of F-18 FDG PET for diagnosis of CS.

Multi-slice representational learning of convolutional neural network for Alzheimer's disease classification using positron emission tomography.

BACKGROUND: Alzheimer's Disease (AD) is a degenerative brain disorder that often occurs in people over 65 years old. As advanced AD is difficult to manage, accurate diagnosis of the disorder is critical. Previous studies have revealed effective deep learning methods of classification. However, deep learning methods require a large number of image datasets. Moreover, medical images are affected by various environmental factors. In the current study, we propose a deep learning-based method for diagnosis of Alzheimer's disease (AD) that is less sensitive to different datasets for external validation, based upon F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). RESULTS: The accuracy, sensitivity, and specificity of our proposed network were 86.09%, 80.00%, and 92.96% (respectively) using our dataset, and 91.02%, 87.93%, and 93.57% (respectively) using the Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset. We observed that our model classified AD and normal cognitive (NC) cases based on the posterior cingulate cortex (PCC), where pathological changes occur in AD. The performance of the GAP layer was considered statistically significant compared to the fully connected layer in both datasets for accuracy, sensitivity, and specificity (p < 0.01). In addition, performance comparison between the ADNI dataset and our dataset showed no statistically significant differences in accuracy, sensitivity, and specificity (p > 0.05). CONCLUSIONS: The proposed model demonstrated the effectiveness of AD classification using the GAP layer. Our model learned the AD features from PCC in both the ADNI and Severance datasets, which can be seen in the heatmap. Furthermore, we showed that there were no significant differences in performance using statistical analysis.

Retrobulbar metastasis of breast primary- Once in a blue moon lesion.

Breast cancer is the most common cancer in females and mostly metastasizes to liver, brain, bones, and lungs. It only rarely involves the choroid; signs of choroidal metastases become apparent late in the course of disease and are therefore linked to bad prognosis. These signs are often ignored as benign symptoms. Although many features may overlap with benign orbital diseases, MRI remains the modality of choice to help differentiate it from others. We present a case of a female patient who presented with visual impairment with unusual imaging features of retrobulbar choroidal metastases from primary breast cancer.

Hypermetabolic Sister Mary Joseph's nodule in pancreatic carcinoma.

Metastasis to umbilicus is often defined as Sister Mary Joseph's (SMJ) nodule. These nodules may be a manifestation of various underlying malignancies, about 50% arising from abdominopelvic cavity most frequently from the gastrointestinal tract. Pancreatic cancer is the predisposing cause in only about 6% of cases and the most common histopathology is adenocarcinomas. We present the case of a 64-year-old male who was found to have a SMJ nodule on staging F18 FDG PETCT scan.

Role of 18F-FLT PET/CT in suspected recurrent or residual lymphoma: final results of a pilot prospective trial.

PURPOSE: To evaluate the role of F-18-Fluorothymidine (FLT) PET/CT in lymphoma patients with suspected recurrent or residual disease. METHODS: Adult lymphoma patients presenting with positive or equivocal F-18-FDG PET/CT at end-treatment or follow-up were prospectively addressed to an additional F-18-FLT-PET/CT. SUV max and tumour-to-background ratios (TBRs) were recorded for the most avid lesion. Biopsy or, when not available, clinical or imaging assessment were employed as standard of reference. RESULTS: Overall 52 patients were recruited. Histology was available in 20/52 patients (38%), proliferation-index (Ki-67) in 14/20. Disease was excluded in 13/52 patients (25%) (one reactive follicular hyperplasia, five reactive-inflammatory tissues, four reactive nodes, two nodal sarcoid-like and one non-specific peri-caecal finding). FDG and FLT scans were concordant in disease restaging in 34/52 patients (65%), whereas in 18/52 cases (35%) relevant discrepancies were recorded. SUV max and TBR were significantly higher in the disease versus the disease-free group, with both tracers (p = 0.0231 and 0.0219 for FDG; p = 0.0008 and 0.0016 for FLT). FLT-SUVmax demonstrated slightly better performance in discriminating benign from malignant lesions (ROC-AUC: 0.8116 and 0.7949 for FLT-SUV max and TBR; 0.7120 and 0.7140 for FDG). Optimal FLT-SUV max cut-offs were searched: three would lead to 95% sensitivity, 81% accuracy, and 39% specificity, whereas seven led to 100%, 41%, and 56% respectively. No statistically significant correlation was observed between the two FLT indices and Ki-67. CONCLUSIONS: According to our results in a clinical setting of recurrent or residual lymphoma, FLT is not significantly superior to FDG and it is unlikely that it will be employed independently. FLT may be restricted to a few specific cases, as complementary to standard FDG imaging, to confirm a diagnosis or to define a better target to biopsy. However, due to FLT suboptimal performance, many findings would remain inconclusive, requiring further diagnostic procedures and reducing the effectiveness of performing an additional FLT scan.

Only strongly enhanced residual FDG uptake in early response PET (Deauville 5 or qPET ≥ 2) is prognostic in pediatric Hodgkin lymphoma: Results of the GPOH-HD2002 trial.

PURPOSE: In 2014, we published the qPET method to quantify fluorodeoxyglucose positron emission tomography (FDG-PET) responses. Analysis of the distribution of the quantified signals suggested that a clearly abnormal FDG-PET response corresponds to a visual Deauville score (vDS) of 5 and high qPET values ≥ 2. Evaluation in long-term outcome data is still pending. Therefore, we analyzed progression-free survival (PFS) by early FDG-PET response in a subset of the GPOH-HD2002 trial for pediatric Hodgkin lymphoma (PHL). PATIENTS/METHODS: Pairwise FDG-PET scans for initial staging and early response assessment after two cycles of chemotherapy were available in 93 PHL patients. vDS and qPET measurement were performed and related to PFS. RESULTS: Patients with a qPET value ≥ 2.0 or vDS of 5 had 5-year PFS rates of 44%, respectively 50%. Those with qPET values < 2.0 or vDS 1 to 4 had 5-year PFS rates of 90%, respectively 80%. The positive predictive value of FDG-PET response assessment increased from 18% (9%; 33%) using a qPET threshold of 0.95 (vDS ≤ 3) to 30% (13%; 54%) for a qPET threshold of 1.3 (vDS ≤ 4) and to 56% (23%; 85%) when the qPET threshold was ≥ 2.0 (vDS 5). The negative predictive values remained stable at ≥92% (CI: 82%; 98%). CONCLUSION: Only strongly enhanced residual FDG uptake in early response PET (vDS 5 or qPET ≥ 2, respectively) seems to be markedly prognostic in PHL when treatment according to the GPOH-HD-2002 protocol is given.

Diagnostic accuracy of F-18 FDG PET or PET/CT for detection of lymph node metastasis in clinically node negative head and neck cancer patients; A systematic review and meta-analysis.

OBJECTIVE: The purpose of the current study was to investigate the diagnostic performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) or positron emission tomography/computed tomography (PET/CT) for the detection of cervical lymph node (LN) metastasis in clinically node negative head and neck squamous cell cancer (cN0 HNSCC) patients through a systematic review and meta-analysis. METHODS: The PubMed and EMBASE database, from the earliest available date of indexing through April 30, 2018, were searched for studies evaluating the diagnostic performance of F-18 FDG PET or PET/CT for the detection of LN metastasis in cN0 HNSCC patients. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR-), and constructed summary receiver operating characteristic (SROC) curves. RESULTS: Across 18 studies (1044 patients), the pooled sensitivity for F-18 FDG PET or PET/CT for the detection of LN metastasis was 0.58 and a pooled specificity of 0.87 for patient based analysis. Neck side based analysis showed the pooled sensitivity of 0.67 and a pooled specificity of 0.85. Level based study demonstrated the pooled sensitivity of 0.53 and a pooled specificity of 0.97 (95% CI; 0.95-0.98). In meta-regression analysis, no definite variable was the source of the study heterogeneity. CONCLUSION: The current meta-analysis showed the low sensitivity and moderate specificity of F-18 FDG PET/CT for the detection of cervical LN metastasis in cN0 HNSCC patients. Level based analysis of F-18 FDG PET or PET/CT has a high specificity and NPV for the detection of cervical metastatic LN detection.

The crying child; physiological variant on F18-FDG PET-CT in a patient of langerhans cell histiocytosis.

F18-FDG PET-CT (Fluorodeoxyglucose Positron Emission Computed Tomography) scanning has a proven role in the staging of various cancers;the physiological distribution of F18-FDG must be understood thoroughly in order to improve the accuracy of image interpretation. We describe the case of a 2 year old child with Langerhans cell histiocytosis, who cried at the time of cannulation before undergoing F18-FDG PET-CT scanning.

Functional visceral fat activity evaluated by preoperative F-18 FDG PET/CT predicts regional lymph node metastasis in differentiated thyroid cancer.

OBJECTIVE: We investigated the predictive role of functional visceral fat activity evaluated by preoperative F-18 FDG PET/CT for regional lymph node metastasis in patients with differentiated thyroid cancer. DESIGN AND PATIENTS: Fifty-eight patients with newly diagnosed differentiated thyroid cancer were enrolled in this study, retrospectively (men 14; women 44; age 53 ± 14.5). They all received preoperative F-18 FDG PET/CT and surgery. Functional visceral fat activity was defined as maximum standardized uptake value (SUVmax) of visceral fat divided by SUVmax of subcutaneous fat (V/S ratio). Pathology results were confirmed through the surgical specimens. RESULTS: The patients with regional lymph node metastasis showed higher functional visceral fat activity (V/S ratio) than the patients without regional lymph node metastasis (2.12 ± 0.6 vs 1.62 ± 0.34, P = .001). V/S ratio of 1.78 was suggested as an optimal cut-off value for predicting regional lymph node metastasis (sensitivity; 70.3%, specificity; 83.3%, area under the curve; 0.778, P < .0001). Furthermore, functional visceral fat activity was significantly associated with regional lymph node metastasis in patients with differentiated thyroid cancer by univariate and multivariate analyses. CONCLUSIONS: Functional visceral fat activity significantly affects the regional lymph node metastasis status in patients with differentiated thyroid cancer. Furthermore, it may also be useful to predict regional lymph node metastasis.

Metabolic topography of autoimmune non-paraneoplastic encephalitis.

PURPOSE: F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) is emerging to be a useful tool in supporting the diagnosis of AIE. In this study, we describe the metabolic patterns on F-18 FDG PET imaging in AIE. METHODS: Twenty-four antibody-positive patients (anti-NMDA-15, anti-VGKC/LGI1-6, and anti-GAD-3), 14 females and 10 males, with an age range of 2-83 years were included in this study. Each PET study was evaluated visually for the presence of hypometabolism or hypermetabolism and semiquantitatively using Cortex ID (GE) and Scenium (Siemens) by measuring regional Z-scores. These patterns were correlated with corresponding antibody positivity once available. RESULTS: Visually, a pattern of hypometabolism, hypermetabolism, or both in various spatial distributions was appreciated in all 24 patients. On quantitative analysis using scenium parietal and occipital lobes showed significant hypometabolism with median Z-score of -3.8 (R) and -3.7 (L) and -2.2 (R) and -2.5 (L) respectively. Two-thirds (16/24) showed significant hypermetabolism involving the basal ganglia with median Z-score of 2.4 (R) and 3.0 (L). Similarly on Cortex ID, the median Z-score for hypometabolism in parietal and occipital lobes was -2.2 (R) and -2.4 (L) and -2.6 (R) and -2.4 (L) respectively, while subcortical regions were not evaluated. MRI showed signal alterations in only 11 of these patients. CONCLUSION: There is heterogeneity in metabolic topography of AIE which is characterized by hypometabolism most commonly involving the parietal and occipital cortices and hypermetabolism most commonly involving the basal ganglia. Scenium analysis using regional Z-scores can complement visual evaluation for demonstration of these metabolic patterns on FDG PET.

Physiological Uptake of F18-FDG in breast parenchyma.

Increased F18-FDG uptake is on PET-CT images should always be assessed carefully for physiological and pathological causes. Breast uptake may be focal or diffuse. Although propensity of tumours increase in focal uptake; diffuse involvement may be seen in lymphoma and some types of breast cancer. Frequently, diffuse breast uptake is non-pathologic due to infection, physiological uptake or lactation. We describe the case of a 27-years old female who underwent 18F FDGPET-CT scan for staging workup of diffuse large B-cell lymphoma (DLBCL). The scan demonstrated bilateral F18-FDG breast uptake, due to ongoing lactation.

False positive finding of F18-FDG in non-Hodgkins lymphoma; an inflamed appendix.

Although PET-CT scanning is a tremendous advancement in oncology; for accurate interpretation, it is important to understand its limitations. Not all PET-positive lesions are cancerous. Both activated macrophages and metabolically active carcinomas will accumulate F18-FDG. Due to limited specificity of FDG-PET/CT, histologic assessment may be required to establish correct diagnosis. We describe a case of 37-year-old man with non-Hodgkin's lymphoma, who underwent F18-FDG PET/CT at the completion of chemotherapy. Imaging showed metabolically active right pelvic soft tissue. Surgical resection confirmed appendicitis.

The role of F-18 FDG PET/CT in evaluating the impact of HIV infection on tumor burden and therapy outcome in patients with Hodgkin lymphoma.

BACKGROUND: To evaluate the impact of HIV infection on tumor burden and therapy outcome following treatment with chemotherapy in patients with Hodgkin lymphoma. METHODS: A total of 136 patients with classical Hodgkin lymphoma were studied (mean age ± SD = 32.31 ± 1.39 years, male = 86, female = 50). Advanced disease (stage III and IV) was present in 64% of patients. HIV infection was present in 57 patients while 79 patients were HIV-negative. Baseline F-18 FDG PET/CT was obtained in all patients. SUVmax, MTV and TLG were determined on the baseline scan to evaluate for tumor burden. All patients completed a standard regimen of adriamycin, bleomycin, vinblastine and dacarbazine (ABVD). After a median period of 8 weeks (range = 6 to 17 weeks), a repeat F-18 FDG PET/CT scan was obtained to evaluate response to therapy using Deauville 5-point scoring system. RESULTS: The HIV-positive and HIV-negative groups were similar with regards to age and disease stage. The groups were heterogeneous with respect to gender (p = 0.029). The SUVmax, MTV and TLG of lesions were not significant different between the two groups. Complete response was seen in 72.8% of the study population. Presence of HIV infection was associated with higher rate of treatment failure with 40.4% of the HIV-positive patients having treatment failure while only 17.7% of the HIV-negative patients had treatment failure (p = 0.0034). HIV infection was a significant predictor of response to chemotherapy. Effects of SUVmax, MTV, TLG and Ann Arbor stage of the disease were not statistically significant as predictors of therapy outcome. In a multiple logistic regression, presence of HIV infection still remained an independent predictor of therapy outcome in the presence of other factors such as SUVmax, MTV, TLG and the Ann Arbor stage of the disease. CONCLUSIONS: HIV infection is not associated with a higher tumor burden in patients with Hodgkin lymphoma. HIV infection is, however, a strong predictor of poor therapy outcome in patients treated with standard regimen of ABVD.