We present the case of a 41-year-old male, suspected to have pulmonary thromboembolism with a history of coronavirus disease 2019 (COVID-19) infection 1 month ago. He presented with dyspnea and dry cough for 2 weeks. D-dimer was >776.70 mcg/L. Lung perfusion scan with Tc-99m macroaggregated albumin revealed multiple bilateral segmental perfusion defects with no mass lesion/consolidation on high-resolution computed tomography (CT) of lungs suggestive of pulmonary embolism (PE) present according to perfusion only modified PIOPED II criteria. CT pulmonary angiogram showed a large filling defect in the right pulmonary artery. The case emphasizes the prolonged sequelae following COVID-19 after recovery from the acute phase of the illness. Lung perfusion scintigraphy can play an important role in the screening of such patients who may be at risk for developing PE as post-COVID-19 sequelae.

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Aim: This study aims to study the clinical-diagnostic relevance of incidental breast uptake (“incidentaloma”) on 18F-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) scan performed for other indications and to correlate it with radiological imaging and histopathology. Materials and Methods: We retrospectively evaluated 3675 FDG-PET scans, identifying 43 patients with breast “incidentaloma.” Thirty of these findings were further investigated with clinical examination, mammography (MMX), UltraSound (US) and/or magnetic resonance (MR). Cases suspected for malignancy underwent US-guided macro-biopsy (USMB) or MR-guided biopsy. Correlations between FDG-PET, radiology findings, age, and histopathology were evaluated. Results: patients who performed both US and MMX were 19. Ten consequently underwent USMB, one MR-guided biopsy, the remaining 8 were not further investigated. Nine patients had a diagnosis of malignancy. Among 11 patients who performed only US and consequently, USMB 6 had a diagnosis of malignancy. Histopathology of the 22 patients with both morphological and glucometabolic alterations showed different types of benign or malignant neoplasia, with a cumulative 68.2% incidence of malignancy. Seven lesions showed a SUV_max >2.5, while the remaining 15 a SUV_max <2.5. There was no statistically significant correlation between SUV_max and histology, therefore SUV_max parameter should not be used to discriminate between benign and malignant findings. No significant correlation between patient age and tumor characterization was found. Conclusions: incidental mammary uptake during an FDG-PET scan may represent a clue suggesting to investigate PET findings. In this subset of patients, early diagnosis may lead to a change in clinical management with a favorable impact on prognosis and a significant reduction in healthcare costs.

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Tuberculosis (TB) is chronic granulomatous infection caused by bacteria, Mycobacterium tuberculosis, which primarily involves the lungs. Abdominal TB is an extrapulmonary disease which can mimic malignancy, especially in women with ascites, weight loss, and high cancer antigen-125 levels. Here, we report a case of young female, where clinical and radiological features were suggestive of ovarian malignancy. However, the pattern of uptake on flourine-18 fluorodeoxyglucose positron emission tomography/computed tomography raised the suspicion of a chronic infectious disease. The final diagnosis was confirmed as TB by cytology and started on antituberculous treatment. She had a good response and remission of lesions after 4 months of treatment.

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Aim: To estimate the standard uptake values (SUVs) of Tc-99m methylene-diphosphonate (Tc-99m MDP) from normal skeletal sites in breast cancer patients using quantitative single-photon emission computed tomography (SPECT). Materials and Methods: A total of 60 breast cancer patients who underwent Tc-99m MDP SPECT/CT study at different postinjection acquisition times were included in this study. Based on postinjection acquisition time, patients were divided into four study groups (n_15 each), i.e. I^st (2 h), II^nd (3 h), III^rd (4 h), and IV^th (5 h). Image quantification (SUVmax and SUVmean) was performed using Q.Metrix software. Delineation of volume of interest was shaped around different bones of the skeletal system. Results: The highest normal SUVmax and SUVmean values were observed in lumber and thoracic vertebra (8.89 ± 2.26 and 2.89 ± 0.58) for Group I and in pelvis and thoracic (9.6 ± 1.32 and 3.04 ± 0.64), (10.93 ± 3.91 and 3.65 ± 0.97), (11.33 ± 2.67 and 3.65 ± 0.22) for Group II, III and IV, respectively. Lowest normal SUVmax and SUVmean values were observed in humerus and ribs (3.22 ± 0.67 and 0.97 ± 0.18), (5.16 ± 1.82 and 1.18 ± 0.16) for Group I, IV, and in humerus (3.17 ± 0.58 and 0.85 ± 0.26), (3.98 ± 1.12 and 1.04 ± 0.28) for Group II and III, respectively. Significant difference (P < 0.05) noted in SUVmax for sternum, cervical, humerus, ribs, and pelvis with respect to time. However, significant difference (P < 0.05) noted in SUVmean for all skeletal sites with respect to time. Conclusions: Our study shows variability in normal SUV values for different skeletal sites in breast cancer patients. Vertebral bodies and pelvis contribute highest SUV values. Time dependency of SUVs emphasizes the usefulness of routinely acquired images at the same time after Tc-99m MDP injection, especially in follow-up studies.

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Background: Optimal peptide concentration in treatment with ¹⁷⁷Lu-DOTATOC/DOTATATE is a matter of debate. Most of the studies with peptide receptor radionuclide therapy mention peptide dose ranging between 100 and 250 μg. The aim of this is to identify possible differences in radiation-absorbed doses (D/Gy) to tumor and kidney as a function of the peptide mass dose in order to identify the most suitable peptide dose for treatment. The therapeutic index (D_tumor/D_kidneys) was assessed as a key parameter for the treatment response. Materials and Methods: Five patients with metastasized Grade 1 to Grade 2 neuroendocrine tumor were analyzed in this study. Patients (n = 4) received two cycles of treatment with intravenously injected ¹⁷⁷Lu-DOTATOC containing peptide mass doses of 200 μg and 90 μg, alternatively; one patient was treated with 90 μg peptide mass in both the therapy cycles. Whole-body (head to mid-thigh) three-dimensional single-photon emission computerized tomography (3D SPECT)/CT images were acquired at 1, 4, 24, 48, and 72 h following the injection of ¹⁷⁷Lu-DOTATOC. Attenuation correction for 3D SPECT images was performed using CT data acquired and fused with the SPECT data (SPECT/CT). Results: Overall, 28 target lesions (liver n = 17, lung n = 4, lymph nodes n = 1, and bone n = 2) were analyzed after 1^st and 2^nd therapy cycles. Tumor normalized absorbed doses varied by a factor of 74 between 0.35 and 26 mGy/MBq. Averaged over all patients, a higher normalized mean tumor dose (10.51 mGy/MBq) was achieved for a peptide dose of 200 μg compared to 90 μg (4.58 mGy/MBq). Kidneys doses varied by a factor of up to 4 between patients (0.25–1.0 mGy/MBq) (independent of dose cycle and peptide dose) and by a factor of up to 2 between dose cycles. The mean kidney dose was 13.7% higher for the 90 μg peptide dose compared to 200 μg. Given the higher tumor dose, the mean therapeutic index of a 200 μg mass dose was considerably higher (16.95), compared to a 90 μg mass dose (9.63). This coincided with the observation, that lesion volume reduction was more pronounced after an initial treatment with a 200 μg mass dose. Biologically effective dose was only 5. 1%–19.3% higher than the absorbed dose for individual dose cycles. Conclusions: Higher peptide dose of 200 μg appears to be more suitable than 90 μg in terms of tumor dose, kidney dose, and therapeutic index for treatment with ¹⁷⁷Lu-DOTATOC.

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Background: Gallium-68-prostate-specific membrane antigen (⁶⁸Ga-PSMA) positron emission tomography/computed tomography (PET/CT) has recently been shown to be very high accuracy in biopsy-naïve prostate cancer (PCa) detection and can potentially improve the low specificity noted with diffusion-weighted magnetic resonance imaging (DW-MRI), especially in instances of prostate inflammation. We aimed to compare the diagnostic accuracy of DW-MRI and PSMA PET/CT using apparent diffusion coefficient (ADC) and maximum standardized uptake (SUV_max) values in the diagnosis of PCa. Patients and Methods: A retrospective study comparing and analyzing the diagnostic accuracy of prebiopsy DW-MRI and ⁶⁸Ga-PSMA PET/CTs done in patients with suspected PCa (raised prostate specific antigen [PSA] and/or positive digital rectal examination) from January 2019 to December 2020. The standard of reference was transrectal ultrasound-guided biopsies. Results: Sixty-seven patients were included in the study, mean age: 70 years (range 49–84), mean PSA: 23.2 ng/ml (range 2.97–45.6). Biopsy was positive for PCa in 56% (n = 38) and negative in 43% (n = 29). Of the benign results, benign hyperplasia was noted in 75% (n = 22) and prostatitis in 25% (n = 7). Of the PCa, 55% (n = 21) of were high International Society of Urological Pathology (ISUP) grade (4–5) and 45% (n = 17) low/intermediate ISUP grade (1–3). Overall the sensitivity/specificity/Accuracy for prediction of PCa of MRI using prostate imaging and reporting data system version 2 criteria and PSMA PET/CT using PCa molecular imaging standardized evaluation criteria was 92.1%/65.5%/80.5% and 76.3%/96.5%/85.1% respectively. Mean apparent diffusion co-efficient (mean ADC) value of benign lesions and PCa was 1.135 × 10^-3 mm²/s and 0.723 × 10^-3 mm²/s, respectively (P = 0.00001). Mean SUV_max and ADC of benign and PCa lesions was 4.01 and 16.4 (P = 0.000246). Mean SUV_max/ADC ratio of benign and malignant lesions was 3.8 × 103 versus 25.21 × 103 (P < 0.000026). Inverse correlation was noted between ADC and SUV_max values (R = −0.609), inverse correlation noted between ADC and Gleason's score (R = −0.198), and positive correlation of SUV_max and SUV_max/ADC with Gleason's score ( R = 0.438 and R = 0.448). Receiver operating characteristic curve analysis revealed a SUV_max cutoff 6.03 (sensitivity/specificity - 76%/90%, area under the curve (AUC) - 0.935, Youden index (YI) - 0.66), ADC cutoff of 0.817 × 10 ⁻³ mm²/s (sensitivity/specificity – 79%/86%, AUC – 0.890, YI - 0.65), and SUV_max/ADC ratio cutoff of 7.43 × 103 (sensitivity/specificity – 87%/98%, AUC - 0.966, YI - 0.85) for PCa diagnosis. Conclusion: For diagnosis of biopsy-naïve PCas, the combination of diffusion-weighted MRI and PSMA PET/CT (i.e., SUV_max/ADC ratio) shows better diagnostic accuracy than either used alone and the combination of PET and MRI is especially useful when distinguishing cancer from prostatitis.

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Lymphomas represent common hematological malignancy, and depending on site, they are classified as nodal or extranodal lymphoma. The term extranodal disease refers to lymphomatous infiltration of anatomic sites other than the primary lymphatic sites; however, the diagnosis of primary versus secondary extranodal lymphoma remains challenging. Among the extranodal locations, gastrointestinal system is the most frequent site. The involvement of the stomach, small intestine, and colon is noted. Rectum as primary site for lymphoma is rare in adults and extremely rare in children. We describe a case of primary rectal lymphoma (high-grade B-cell non-Hodgkin's lymphoma) in 11-year-old child. We believe that reporting this case will add to the data about clinical presentation, radiological, nuclear medicine findings, and treatment approaches of primary rectal lymphoma.

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Primary lymphomatous involvement of spinal cord, nerve roots, and cauda equina is a rare entity and comprises only 0.1% of extra-nodal lymphoma spectrum. Here, we present a case of non-Hodgkin lymphoma involving cauda equina, initially suspected as ependymoma on magnetic resonance imaging that was later confirmed on nerve root biopsy as high B cell non-Hodgkin's lymphoma of L1-S1 nerve roots. F-18 fluorodeoxyglucose positron emission tomography-computed tomography was performed for staging workup which showed abnormal metabolic activity within the spinal canal from D10-S2 with no evidence of distant organ involvement.

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Giant cell tumors (GCTs) are benign bone lesions which are treated with curettage and bone grafting. Infrequently, GCTs show local site recurrences which are then treated with either surgical excision or radiation therapy. Radiation-induced sarcoma is rarely seen as a late complication of radiation therapy which needs to be differentiated from recurrent GCT. We report one such rare case of radiation-induced sarcoma detected on Flourine-18 fluorodeoxyglucose (18F FDG) positron emission tomography/computed tomography in a 40-year-old male who was treated with radiation therapy for recurrent GCT 9 years ago.

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Multi-targeted tyrosine kinase inhibitor (TKI) pazopanib approved for the treatment of advanced soft tissue sarcoma (STS) has prolonged the estimated survival times and quality of life of patients. However, several adverse effects associated predominantly with the inhibition of the vascular endothelial growth factor receptor by these drugs may prove to be potentially life-threatening. One such rare adverse event with the use of pazopanib is acute pancreatitis. We present a case of asymptomatic necrotizing pancreatitis induced by pazopanib treatment for metastatic STS detected on ¹⁸F-FDG PET-CT imaging.

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Renal cell carcinoma is a common urogenital malignancy. It often metastasizes to the lungs, liver, bone, adrenal glands, and brain in the advanced stage. However, the involvement of the skin and subcutaneous region of the head and neck is rare. We report a case of a middle-aged man presented with extensive metastases to post radical nephrectomy. The nose and lower lip metastasis with submental lymph nodal mass is not previously reported. He also had metachronous prostatic adenocarcinoma. The case highlights the excellent capability of molecular imaging using fluorodeoxyglucose-positron-emission tomography/computed tomography to pick up all metastatic lesions and find metachronous prostate malignancy.

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An 12-year-old boy with relapse of acute lymphocytic leukemia and suspected skeletal involvement underwent mTc-Methylene Di-Phosphonate skeletal scintigraphy, which revealed a lytic “cold” lesion in the pelvis and diffuse splenic uptake. There was no active splenic infiltration in cross-sectional imaging. However, the patient had a history of multiple blood transfusions, which is a rare cause for diffuse splenic uptake.

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Osteoblastoma accounts for approximately 1% of all primary bone tumors. We report F18-fluorodeoxyglucose positron emission tomography/computed tomography (F18-FDG PET/CT) findings of an osteoblastoma in the rib of a 20-month-old girl child, who had fever with pain in the right shoulder for 4 months. This lesion was initially judged as a malignant bone tumor but a biopsy revealed it to be an osteoblastoma. The age of patient and predominant site of disease involvement contributes to uniqueness of our case. In our case, F18-FDG PET/CT has facilitated biopsy planning and ruled out other sites of disease involvement.

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Gastric cancer is one of the important causes of cancer-related mortality worldwide, with significantly low median survival in metastatic gastric cancer. Thus, when planning treatment for gastric cancer, it becomes important to determine whether or not there is metastasis. Bone marrow is a rare region for metastasis in cases of gastric carcinoma, as suggested by the literature. We are herewith presenting the case of a 56-year-old patient of recurrent gastric carcinoma who showed a rare site of metastasis involving marrow on fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scan.

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Parathyroid adenoma sometimes present in ectopic location and may pose a difficulty in both diagnosis and localization. We report a case of a young lady suspected to have neuroendocrine tumor of the mediastinum demonstrating synaptophysin positivity on an initial core needle biopsy. Ga-68 DOTANOC positron emission tomography–computed tomography revealed a somatostatin receptor-expressing lesion in the anterior mediastinum with tracer avid multiple lytic bone lesions. On further biochemical and imaging workup with Tc-99 m SESTAMIBI, a diagnosis of ectopic parathyroid adenoma was made which was further confirmed with surgical excision.

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A 42-year-old male presented with weight loss and progressively increasing pain and swelling in joints over the past 3 months. Contrast-enhanced computed tomography (CT) demonstrated pleuropulmonary opacities and supra/infradiaphragmatic lymph nodes enlargement. Positron emission tomography (PET/CT) with ¹⁸F-fluorodeoxyglucose showed intensely increased tracer uptake in joints, in pulmonary opacities, as well as in thoracic, iliac, and inguinal nodes. On suspicion of lymphoma with synovial involvement, he was submitted to lymph node and synovial biopsy, which revealed reactive follicular lymphadenopathy and synovium inflammatory changes, respectively. Rheumatoid factor resulted increased, and thus, diagnosis of rheumatoid arthritis with related lung and lymph node involvement was made.

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Autoimmune encephalitis with antibodies against neuronal cell surface antigens is a group of neuropsychiatric disorders, with anti-N-methyl D-aspartate (NMDAR) encephalitis being one of them. We report a case of a young male patient who presented with complaints of seizures associated with fever, rapidly progressing memory loss, and choreoathetoid movements for 1 month. His serum was strongly positive for anti-NMDAR receptor antibodies. F-18 fluorodeoxyglucose positron-emission tomography/computed tomography for the brain revealed hypermetabolism involving bilateral basal ganglia and bilateral mammillary bodies associated with hypometabolism in bilateral occipital lobes.

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A variety of fungal pulmonary infections can produce radiologic findings that mimic malignancy. Distinguishing these infectious lesions from malignancy remains challenging for physicians. We describe one such case where fungal lung nodule mimicked metastasis on fluorodeoxyglucose positron emission tomography/computed tomography scan.

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Spontaneous pneumomediastinum is a rare condition, characterized by the presence of air in the mediastinum without any apparent precipitating cause. It is mainly a radiological diagnosis. The onus of differentiating between secondary and spontaneous pneumomediastinum lies on a thorough workup. In addition to etiology, complications such as tension pneumomediastinum, cervical emphysema, and pneumorachis. When present, must be diagnosed promptly. Spontaneous pneumomediastinum is a benign condition which is usually managed conservatively. Although not routinely seen on positron emission tomography/computed tomography, when present, they must be picked up and reported accurately to guide appropriate management of the patient.

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Cardiac metastasis from lung cancer is rare. They are clinically silent and often diagnosed only postmortem. Cardiac magnetic resonance imaging (MRI) provides interesting information about the tissue characterization and vascularization of the tumor. The 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) shows hypermetabolism in the cardiac metastasis. We present a case of a 74-year-old male, diagnosed with squamous cell carcinoma of the lung, who underwent cardiac MRI which showed a right intracavitary mass. We share interesting images, detected on 18F-FDG PET/CT, of cardiac metastasis.

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Malignant fibrous histiocytoma (MFH)/undifferentiated pleomorphic sarcoma (UPS) is an uncommon malignancy in the head-and-neck region. UPS is a malignant neoplasm of uncertain origin that arises both in soft tissue and bone. We bring forth a 65-year-old female who presented with an ulceroproliferative growth in the right upper neck. Contrast-enhanced magnetic resonance imaging and ¹⁸F-fluorodeoxyglucose positron emission tomography–computed tomography revealed a large exophytic, solid-cystic growth in the right parotid region with locoregional extension and few ipsilateral lymph nodes. Biopsy of the lesion revealed UPS, which was previously called MFH. She was considered for chemoradiotherapy. Correlative imaging helps in adequate staging of large tumors with assessment of response to chemoradiotherapy.

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Background: We estimated plasma amyloid-peptides levels (Aβ_1-42 and Aβ_1-40) as diagnostic biomarker of Alzheimer's disease (AD) and evaluated its association with clinical severity and 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) Z score of the different brain regions in the Indian population. Patients and Methods: A case-control study was conducted. Diagnostic and statistical manual-IV, Dubois, and NIA-AA criteria were used for the diagnosis of AD. The plasma Aβ_1-42 and Aβ_1-40 concentration and 18F-FDG PET Z score were estimated for different brain regions. Results: Forty-seven cognitive impairment patients (AD = 29, mild cognitive impairment = 18) and 33 age-matched controls were enrolled. Plasma Aβ_1-42 level was significantly higher in the AD group compared to controls (P = 0.046) and a cut-off >5.7 ng/mL has a specificity of 96.9%, sensitivity of 27.6%, positive predictive value 88.9%, and negative predictive value 60.4% for differentiating AD patients from controls. Significant correlation was seen between Aβ_1-40/Aβ_1-42 ratio and 18F-FDG PET Z score in the bilateral-parietal, temporal, frontal-association area, and posterior-cingulate areas. Conclusion: As a diagnostic biomarker of AD, plasma Aβ_1-42 level showed good specificity but low sensitivity in the Indian population.

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Objective: The objective is to evaluate incidental detection of COVID-19 lung involvement in asymptomatic individuals who undergo fluorodeoxyglucose (FDG) positron emission tomography-computerized tomography (PET/CT) scans for oncologic indications. Patients and Methods: The study was conducted in a tertiary care oncology hospital and included patients who were asymptomatic for COVID-19 infection and underwent FDG PET/CT scans for standard oncologic indications between April 15, 2020, and September 30, 2020. Patients who showed CO-RADS category 4/5 changes (high level of suspicion) on the CT chest component of the PET/CT study were considered for analysis. CT severity score, presence of FDG uptake, and maximum standardized uptake value of FDG avid lung involvement were noted and correlated with reverse transcriptase-polymerase chain reaction (RT-PCR) test. Results: 1982 PET/CT scans were performed, 78 (3.9%) patients showed lung changes with high degree of suspicion of COVID-19 pneumonia (CO-RADS 4/5). Hematolymphoid and head-neck cancer were the most common tumor types (23%), and restaging/response evaluation was the most common PET/CT indication. Of the patients who underwent RT-PCR testing, 70% showed a positive result. The mean CT severity score was 6 (standard deviation 5.9) with no significant difference seen between the RT-PCR positive and negative groups. FDG avidity in lung lesions was noted in 41 out 57 (72%) patients. A significant correlation was seen between the RT-PCR positivity and FDG uptake in lung lesions. Conclusion: A small but significant proportion of patients undergoing routine oncologic PET/CT scans showed incidental COVID-19 lung involvement. Lung involvement in these asymptomatic patients showed a low CT severity score in all patients and FDG avidity in majority. Timely detection of such incidental cases can initiate further confirmatory RT-PCR testing and isolation measures that not only influence patient's cancer treatment protocols but also have a larger community impact of limiting the spread of infection.

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Objectives: The objective of this study was to evaluate the diagnostic accuracy of multiparametric magnetic resonance imaging (mpMRI) and ⁶⁸Ga prostate-specific membrane antigen positron emission tomography–computed tomography (PSMA PET-CT) and respective quantitative parameters (K^trans – influx rate contrast, K_ep – efflux rate constant, ADC – apparent diffusion coefficient, and SUVmax ratio – prostate SUVmax to background SUVmax ratio) in detection and localization of clinically significant prostate cancer (CSPCa) in D'Amico intermediate- and high-risk group patients (prostate-specific antigen [PSA] >10 ng/ml). Methodology: The study included thirty-three consecutive adult men with serum prostate specific antigen >10ng/ml, and systematic 12 core prostate biopsy proven prostate cancer. All the 33 patients, were evaluated with mpMRI, and ⁶⁸Ga PSMA PET-CT. The biopsy specimens and imaging were evaluated for 12 sectors per prostate by a predetermined scheme. Results: MpMRI Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) score ≥3 showed higher sensitivity than ⁶⁸Ga PSMA PET-CT (96.3% vs. 82.4%), with similar specificity (54.5% vs. 54.5%) (n = 33 patients, 396 sectors). Combined use of MRI and ⁶⁸Ga PSMA PET-CT in parallel increased sensitivity (99.5%) and NPV (98.7%) for detection of CSPCa and combined use of MRI and ⁶⁸Ga PSMA PET-CT in series increased specificity (71.8%) and PPV (71.5%) (n = 33 patients, 396 sectors). ADC showed a strong negative correlation with Gleason score (r = −0.77), and the highest discriminative ability for detection and localization of CSPCa (area under curve [AUC]: 0.91), followed by K^trans (r = 0.74; AUC: 0.89), PI-RADS (0.73; 0.86), SUVmax ratio (0.49; 0.74), and K_ep (0.24; 0.66). Conclusion: MpMRI PI-RADS v2 score and ⁶⁸Ga PSMA PET-CT (individually as well as in combination) are reliable tool for detection and localization of CSPCa. Quantitative MRI and ⁶⁸Ga PSMA PET-CT parameters have potential to predict Gleason score and detect CSPCa.

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Context: Extranodal (EN) lymphomas involve sites other than lymph nodes (LNs), spleen, thymus, and the pharyngeal lymphatic ring. The highest standardized uptake value (SUV) max of the LN can aid in the diagnosis of EN site lymphomatous infiltrations over inflammation or infection especially when there are no contrast-enhanced computed tomography (CT) changes. Aims: The purpose of this study was to find the significance of correlation between absolute SUVmax and mediastinal blood pool (mbSUVmax) and liver (lvSUVmax) normalized SUVmax of EN sites and the most fluorodeoxyglucose (FDG) avid LN in patients with primary and secondary EN involvement in Non-Hodgkin's and Hodgkin's Lymphoma. Settings and Design: This was a retrospective study of 70 patients with histopathologically proven lymphoma in whom 18F-FDG positron emission tomography CT was performed for pretherapy staging. Materials and Methods: Images were used to detect EN sites of disease and SUVmax of mediastinal blood pool, liver, highest SUVmax LN, and highest SUVmax EN site were calculated. Statistical Analysis Used: Karl Pearson's coefficient of correlation (r) was used to correlate the highest SUV max of LN and EN site and corresponding highest blood pool corrected and liver corrected SUV max. In view of small sample size, t-test for paired samples at 5% and 10% significance was conducted to validate the findings. Two-tailed t-test for independent samples was also used to compare means of SUVmax values between data grouped according to gender and lymphoma subtype (Non-Hodgkin lymphoma and Hodgkin lymphoma). Results: r = 0.54 for the highest LN SUVmax-highest EN SUVmax values and on further validation by one- and two-tailed paired t-test at significance levels of 5% and 10%, P = 0.00052 and 0.00103 respectively which denoted significant positive and moderate correlation. r = 0.59 for highest LN lvSUVmax-highest EN vSUVmax and P = 0.00032 and 0.00065 showing positive and moderate correlation. r = 0 0.82 for highest LN mbSUVmax-highest EN mbSUVmax values and P = 0.00034 and 0.00068 revealing positive and strong correlation. Conclusion: Significant positive and strong correlation exists between nodal and EN mbsUVmax. This is stronger than the correlation between nodal and EN absolute SUVmax and lvSUVmax. Since normalization of lesion SUVmax to reference tissues reduces the variability of SUV, this can be a useful adjunct to determine whether high SUVmax of the EN site is due to lymphomatous infiltration.

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