Multiple Nervous System Involvement of Erdheim-Chester Disease With Responsive Perinephritic Hypermetabolism.

ABSTRACT: A 36-year-old man who was at follow-up for histiocytosis had sudden-onset symptoms of unilateral ophthalmic increased pressure. The patient was referred to the FDG PET/CT for determination of involvement with suspicion of Erdheim-Chester disease. The reduction of the FDG uptake in all of the lesions (medial temporal lobes, nasal septum, medulla spinalis in sacral region, as well as perinephritic infiltrations), which were determined by the first PET/CT, was achieved at second imaging.

68Ga Prostate-specific Membrane Antigen Uptake in Metastatic Medullary Thyroid Carcinoma.

We present the case of a 58-year-old man with advanced medullary thyroid carcinoma who had a treatment history with different types of modalities. In the follow-up, the patient had rising calcitonin and CEA levels. Metastatic lymph nodes, liver, and bone metastases with varying degrees of uptake were detected on 18F-fluorodeoxyglucose (FDG) and 68Ga-DOTATATE positron emission tomography/computed tomography (PET/CT). 68Ga prostate-specific membrane antigen (PSMA) PET/CT was performed to explore whether the patient might have a chance for PSMA-targeted radionuclide therapy, and increased PSMA expression was noted in most of the metastatic lesions, even some of which have higher PSMA uptake than 18F-FDG and 68Ga-DOTATATE.

18F-fluorodeoxyglucose positron emission tomography/CT in the diagnosis of right-sided endocarditis in children and adults with infective endocarditis.

OBJECTIVE: Infectious endocarditis poses a diagnostic challenge due to its highly variable clinical presentation. To establish a definitive diagnosis, different imaging modalities are essential. In recent years, positron emission tomography/CT has gained increasing significance in diagnosing infective endocarditis; however, its application in the pediatric age group remains limited. This study encompasses patients definitively or potentially diagnosed with infectious endocarditis at our institution from 2018 to 2023. METHODS: A total of 29 patients underwent 18F-fluorodeoxyglucose positron emission tomography/CT examinations, with 19 of them presenting with right-sided infective endocarditis. RESULTS: Evidence consistent with infective endocarditis was observed in 18 (94.7%) of the patients. Pulmonary septic embolism was identified in 15 (78.9%) cases, and splenic involvement was noted in 12 (57.8%) cases. Transthoracic/transesophageal echocardiography failed to reveal vegetation or provided uncertain results in six patients, whereas fluorodeoxyglucose-positron emission tomography-CT exhibited involvement. Subsequently, the diagnosis of infective endocarditis was confirmed post-surgery based on the fluorodeoxyglucose-positron emission tomography-CT findings. CONCLUSION: Our results, along with our clinical experience, demonstrate that fluorodeoxyglucose-positron emission tomography-CT is a safe and viable method for diagnosing right-sided endocarditis, which is often challenging to visualize using echocardiography.

Bone Metabolism in Men who Live with HIV Aged 50 years and Over: Impact of Infection Duration.

BACKGROUND: Early diagnosis and effective antiretroviral therapy (ART) lead to similar life expectancy in people living with HIV (PLWH) compared to the general population. This population faces problems such as decreased bone mineral density (BMD) and increased fracture risk. The aim of this study was to determine the prevalence of osteoporosis in men aged 50 years and over who were PLWH and to determine risk factors and changes in bone metabolism with bone turnover markers. METHODS: 79 male PLWH aged 50 years and over were followed up in our outpatient clinic between May 2021 and October 2021. The patients' demographic, clinical, laboratory, and DEXA data were analyzed. Serum levels of bone turnover markers were measured. RESULTS: The prevalence of osteopenia, osteoporosis, and normal BMD was found to be 55.7%, 13.9%, and 30.4%, respectively. A correlation was found between low BMD and low body mass index, elapsed time since diagnosis of HIV infection, high rate of use of ART, and long usage time of tenofovir disoproxil fumarate + protease inhibitor. A one-year increase in HIV infection duration was associated with an increased risk of low BMD by 1.246. CONCLUSION: Compared to studies conducted on the general population, the prevalence of osteoporosis in male PLWH aged 50 years and older was two times higher. The limited effect of the duration of ART use on low BMD may be due to the patients' histories of replacement therapy. Therefore, to eliminate the negative effects of ART on BMD, it may be beneficial to start replacement therapy when necessary.

Unexpected Symmetrical Uptake of 18 F-FDG of Distal Peripheral Bones in a Patient With Diffuse Large B-Cell Lymphoma.

ABSTRACT: A 74-year-old woman was referred for 18 F-FDG PET/CT scanning to investigate an underlining etiology due to recently developed unexplained bone pains and lack of walking capacity. On the initial PET/CT scan, we have noted a highly symmetrical and apparent intramedullary FDG uptake of the distal parts of appendicular skeleton system including the bilateral elbows, wrists, and foot ankles in addition to a lymphadenomegaly in the right groin. The excisional biopsy from the lymph node of right groin revealed a diagnosis of diffuse large B-cell lymphoma.

Synchronous occurrence of medullary and papillary thyroid cancer and survival rates.

PURPOSE: Concurrence of medullary and papillary thyroid carcinoma (MTC and PTC) represents less than 1% of all thyroid malignancies. We aimed to reveal the demographic and clinical characteristics of this rare pathology and to evaluate the effect of the same or contralateral lobular localization of these two malignancies in clinical and laboratory features. Evaluation of progression-free survival (PFS) in current pathology is one of the important features of our study. METHODS: All patients diagnosed with simultaneous MTC and PTC after thyroidectomy were evaluated retrospectively. Data on the following variables were recorded: age, gender, tumor localization (ipsilateral lobe located MTC and PTC-Group I, contralateral lobe located MTC and PTC-Group II), tumor size, cervical lymph node metastasis, distant metastasis, tumor stage, postoperative basal calcitonin, carcinoembryonic antigen, thyroglobulin (Tg), and anti-Tg values. In all our cases, since MTC progressed before PTC, progression was accepted as serum calcitonin values exceeded 150 pg/mL. RESULTS: Groups were formed as follows: Group I, four cases where MTC and PTC were localized in different foci in the same lobe; Group II, nine cases where they were localized in different lobes. There was only one case in which two tumors were located in the same focus. The case with dual differentiation was included in Group I (35. 7%). When the PFS of the two groups were compared, no statistically significant difference was found ( P = 0.87). CONCLUSIONS: As a result of this analysis, the location of the simultaneously detected PTC in the same or different lobes with the MTC does not make a significant difference in clinical and laboratory features.

A multi-institutional assessment of eye lens dose in nuclear medicine clinics.

AIM: The endeavor was to measure the lens dose of actively working staff in nuclear medicine departments. MATERIAL AND METHODS: This study was accomplished in three nuclear medicine sites. A total of 23 workers in nuclear medicine joined this work. Among them are 6 SPECT/ CT technologists, 6 PET/CT technologists, 3 PET/MRI technologists, 5 radiopharmacists, 2 physicists, and 1 physician. EXTDOSE Hp(3) OSL dosimeter with tissue equivalent beryllium-oxide crystal was used for lens dose measurement. All participants were asked to wear the lens dosimeter for 2 months as near to the eye level as possible. RESULTS: Pooling the dose measures together yielded an average lens dose of 1.48 ±â€…0.77 mSv for the radiopharmacy team, 1.44 ±â€…0.26 for PET/ CT technologists, 0.86 ±â€…0.45 mSv for SPECT/ CT technologists, 0.38 mSv for the sole physician administered 177Lu, and 0.45 ±â€…0.02 mSv for the physicists conducting 131I therapy. Moreover, normalizing the lens dose to the labeled activity led to a lens dose of 2.2 ±â€…1.4 µSv/GBq for the radiopharmacy team. Likewise, per administered activity: 23.8 ±â€…7.3 µSv/GBq for PET/CT and PET/MRI technologists, 12.2 ±â€…10.5 µSv/GBq 99mTc for SPECT/CT technologists, 6.0 ±â€…0.81 µSv/GBq 131I for physicists, and 3.0 µSv/GBq 177Lu for the physician. CONCLUSION: It was deduced that the annual occupational lens dose of the nuclear medicine workers varied from 2.3 to 11.5 mSv/year; however, one radiopharmacist projected annual lens dose as close to the lens equivalent dose limit (20 mSv/year) as 17.9 mSv.

18F-FDG PET/MRI Image of Skin Metastasis of Ovarian Cancer.

Ovarian cancer is one of the deadliest tumors among women. It mostly metastasizes to the liver, pleura, lungs, and bones. We present a sixty-six-year-old patient with skin lesions. The patient who underwent biopsy due to skin lesions was diagnosed with ovarian cancer. 18F-fluorodeoxyglucose (FDG) positron emission tomography/magnetic resonance imaging (PET/MRI) performed for metastasis search shows widespread skin involvement, especially in the lower abdomen and legs. Skin involvement it ovarian cancer can be rarely seen, and in this article we would like to share 18F-FDG PET/MRI of skin involvement in ovarian cancer.

Rituximab in the management of retroperitoneal fibrosis: A single tertiary rheumatology care center experience.

AIM: To investigate the clinical and radiological outcomes and glucocorticoid-sparing effect of rituximab therapy in 13 patients with retroperitoneal fibrosis (RPF). METHODS: We analyzed the data of both glucocorticoid-naive and glucocorticoid-resistant RPF patients who were treated with rituximab. Demographic features, positron emission tomography computed tomography (PET-CT) findings, and clinical and histopathologic outcomes were collected retrospectively. RESULTS: We evaluated the data of 13 RPF patients (8M/5F). The median follow-up duration was 28 months (interquartile range [IQR] 24.5-55.5 months) and median age at the time of diagnosis was 50.8 years (IQR 46.5-54.5 years). PET-CT scans showed that following the rituximab therapy, the craniocaudal diameter of the RPF mass reduced from 74 mm (IQR 50.5-130 mm) to 52 mm (IQR 35-77 mm; p = .06), and periaortic thickness of the RPF mass reduced from 14 mm (5.5-21.9 mm) to 7 mm (4.5-11 mm; p = .12). The maximum standardized uptake value (based on body weight) of the RPF mass decreased from 5.8 (4.3-9.7) to 3.1 (2.8-5.3) after the therapy (p = .03). The number of patients with hydronephrosis reduced from 11 to 6 following rituximab therapy (p = .04). Before rituximab, nine patients received a median dose of 10 mg (IQR 0-27.5 mg) prednisolone per day. After the rituximab treatment, we discontinued prednisolone treatment for four out of nine patients and reduced the daily dose for the remaining patients. At the time of the final evaluation of the patients, the median prescribed prednisolone dose was 5 mg/day (IQR 2.5-7.5 mg/day; p = .01). CONCLUSION: Our study shows that rituximab may be a favorable treatment option for glucocorticoid-refractory RPF patients with high disease activity on PET-CT scans.

Bilateral Lymphadenopathy After COVID Vaccine in 18F-Choline PET/MRI Performed for Hyperparathyroidism.

ABSTRACT: We describe a case of a 56-year-old woman with primary hyperparathyroidism. 18F-Choline PET/MRI revealed incidental bilateral axillary lymphadenopathy with mild-moderate increased 18F-choline uptake. The patient had her first and third doses of COVID-19 vaccines from the left arm and second dose of vaccine from the right arm before PET examination.

SPECT/CT-based dosimetry of salivary glands and iodine-avid lesions following 131I therapy.

Objective: The purpose was to provide uptake and radiation dose estimates to salivary glands (SG) and pathologic lesions following radioiodine therapy (RIT) of differentiated thyroid cancer patients (DTC). Methods: A group of DTC patients (n = 25) undergoing 131I therapy joined this study with varying amounts of therapeutic activity. Sequential SPECT/CT scans were acquired at 4 ± 2, 24 ± 2, and 168 ± 3 h following administration of 3497-9250 MBq 131I. An earlier experiment with Acrylic glass body phantom (PET Phantom NEMA 2012 / IEC 2008) was conducted for system calibration including scatter, partial volume effect and count loss correction. Dose calculation was made via IDAC-Dose 2.1 code. Results: The absorbed dose to parotid glands was 0.04-0.97 Gy/GBq (median: 0.26 Gy/GBq). The median absorbed dose to submandibular glands was 0.14 Gy/GBq (0.05 to 0.56 Gy/GBq). The absorbed dose to thyroid residues was from 0.55 to 399.5 Gy/GBq (median: 21.8 Gy/GBq), and that to distal lesions ranged from 0.78 to 28.0 Gy/GBq (median: 3.12 Gy/GBq). 41% of the thyroid residues received dose > 80 Gy, 18% between 70-80 Gy, 18% between 40-70 Gy, and 23% has dose < 40 Gy. In contrast, 18% of the metastases exhibited a dose > 80 Gy, 9% between 40-60 Gy, and the dose to the vast majority of lesions (64%) was < 40 Gy. Conclusion: It was inferred that dose estimation after RIT with SPECT/CT is feasible to apply, together with good agreement with published 124I PET/CT dose estimates. A broad and sub-effective dose range was estimated for thyroid residues and distal lesions. Moreover, the current methodology might be useful for establishing a dose-effect relationship and radiation-induced salivary glands damage after RIT.

Hybrid Ga-68 prostate-specific membrane antigen PET/MRI in the detection of skeletal metastasis in patients with newly diagnosed prostate cancer: Contribution of each part to the diagnostic performance.

PURPOSE: Bone metastasis is essential in patients with prostate cancer (PCa) as it determines prognosis and survival. Hybrid PET/MRI allows simultaneous acquisition of PET and MRI data, thus combining the strength of both technologies allows the detection of bone marrow metastases that are missed by PET/CT. In this retrospective study, we aimed to evaluate the diagnostic efficiency of hybrid PET/MRI with Ga-68 prostate-specific membrane antigen (PSMA) in detecting skeletal metastases in newly diagnosed PCa patients and compared the effectiveness of stand-alone PSMA PET reviewing versus stand-alone whole-body (WB) MRI evaluation. We also investigated the effect of the interpretation of all PET/MR data together on clinical management. METHODS: We studied 74 newly diagnosed PCa patients who underwent PSMA PET/MRI for staging purposes. At first, PET and MRI were evaluated separately for bone lesions on a patient-and-lesion basis and then a further joint PSMA PET/MRI interpretation was made. RESULTS: Patient-based sensitivity, specificity, positive predictive value, negative predictive value and accuracy analysis for bone metastasis was, respectively, 1.0, 0.83, 0.54, 1.0, 0.86 for PET; 0.75, 0.96, 0.81, 0.95, 0.93 for WB MRI and 0.91, 0.95, 0.78, 0,98, 0.94 for PET/MRI. The combined PET/MRI evaluation changed the clinical impact in 13.5% of patients (eight correct and two wrong decisions) compared to PET stand-alone interpretation. CONCLUSION: PSMA PET imaging showed superior sensitivity to WB MRI in detecting bone metastases in newly diagnosed PCa patients, whereas WB MRI has superior specificity and PPV. Furthermore, the specificity and PPV of joint PET/MRI evaluation are better than PSMA PET alone. Despite the longer acquisition period, adding WB MRI sequences to PSMA PET imaging appears beneficial for PCa patient management.

Simplification of dosimetry in 90Y-radioembolization therapy by dual planar images.

AIM: The purpose was to provide a practical and effective method for performing reliable 90Y dosimetry based on 99mTc-MAA and SPEC/CT. The impact of scatter correction (SC) and attenuation correction (AC) on the injected 90Y activity, lung shunt fraction (LSF) and the delivered dose to lung and liver compartments was investigated within the scope of the study. MATERIAL AND METHODS: Eighteen eligible patients (F: 3, M: 15) were subjected to 90Y therapy. 99mTc-MAA (111-222 MBq) was injected into the targeted liver, followed by whole-body scan (WBS) with peak-window at 140 keV (15% width) and one down-scatter window. SPECT/CT scan was subsequently acquired encompassing lung and liver regions. The LSFs were fashioned from standard WBS LSFwb (St), scatter corrected WBS LSFwb (Sc), only scatter corrected SPECT LSFspect (NoAC-SC) and SPECT/CT with attenuation and scatter correction LSFspect (AC-SC). The absorbed doses that would be delivered to tumor and injected healthy liver were estimated using different calculation modes involving AC-SC (SPECT/CT), NoAC-SC (SPECT), NoAC-NoSC+LSFwb (SC), AC-SC + LSFwb (St), and NoAC-NoSC+LSFwb (St). RESULTS: The average deviations (range) in LSF values between standard LSFwb (St) and those from SPECT/CT (AC-SC), SPECT (NoAC-SC), and LSFwb (SC) were - 50% (- 29/- 71), - 32% (- 8/- 67), and - 45% (- 13/80), respectively. The suggested 90Y activity (GBq/Gy) was decreased within a range of 2-11%, 1-9%, and 2-7% by using LSFspect (AC-SC), LSFspect (NoAC-SC), and LSFwb (SC), respectively. Overall, two-sample t-test yielded no statistically significant difference (p < 0.05) in the absorbed doses to tumor and injected healthy liver between AC-SC (SPECT) and the rest of approaches with/and without AC and SC. However, a statistically significant difference (p < 0.05) was demonstrated in the lung shunt fractions and lung doses due to AC and SC. The LSFs from scatter corrected planar images LSFwb (SC) exhibited well agreement (R2 = 0.92) with SPECT/CT (AC-SC) and there was no statistically significant difference (Pvalue > 0.05) between both methods. CONCLUSION: It was deduced that SPECT/CT with attenuation and scatter correction plays a crucial role in the measurements of lung shunt fraction and dose as well as the total number of 90Y treatments. However, the absorbed dose to tumors and injected healthy liver was minimally affected by AC and SC. Besides, a good agreement was observed between LSF datasets from SPECT/CT versus scatter corrected WBS that can be alternatively and effectively used in 90Y dosimetry.

The analysis of 18 F-FDG PET/MRI, electroencephalography, and semiology in patients with gray matter heterotopia: A pilot study.

OBJECTIVES: To describe 18 F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18 F-FDG PET/MRI) along with semiology and electroencephalography (EEG) in patients with gray matter heterotopia (GMH); to evaluate the concordance between 18 F-FDG PET/MRI and clinical epileptogenic zone (EZ). MATERIALS & METHODS: GMH (subcortical heterotopia [SCH] and periventricular nodular heterotopia [PNH]) patients with epilepsy who underwent 18 F-FDG PET/MRI were retrospectively enrolled. Two radiologists evaluated brain MRI, while two nuclear medicine specialists assessed the 18 F-FDG PET. The SUVmax values of visually hypometabolic cortical areas were compared to the contralateral cortex using a SUVmax threshold value of 10%; the SUVmax values of GMH lesions were compared with that of the right precentral gyrus. The cortex or GMH with hypometabolism on 18 F-FDG PET/MRI was considered representative of the EZ. The clinical EZ was identified using EEG and semiology. RESULTS: Thirty patients (19 PNH; 11 SCH) with a mean age of 28.46 ± 9.52 years were enrolled. The heterotopic nodules were ametabolic in 3 patients (10%), hypometabolic in 16 (33.33%), isometabolic in 13 (26.66%), and hypermetabolic in 4 (10%). 18 F-FDG PET/MRI demonstrated hypometabolism in the cortex and GMH in 22/30 (73.33%) and 16/30 (53.33%). We could identify a clinical EZ in 18 patients, and 15 out of 18 (83.33%) had concordant 18 F-FDG PET/MRI findings. CONCLUSION: Heterotopic nodules in GMH patients show different metabolic patterns on 18 F-FDG PET/MRI, with nearly three-quarters of the patients having cortical hypometabolism. 18 F-FDG PET/ MRI findings are mostly concordant with the clinical EZ.

Mesenteric Panniculitis Appears as Metastatic Disease on 18F-FDG-PET/CT Scan.

Mesenteric panniculitis is a rare benign inflammatory process involving mesenteric adipose tissue and the pathogenesis is still unknown. It may present 18Fluorine-fluorodeoxyglucose (18F-FDG) uptake and appear like a malign tumor or metastatic disease. We report a case of 47 year-old woman with serous ovarian adenocarcinoma demonstrating intense 18F-FDG uptake and hyperdense nodularity in mesenteric fatty tissue on post-chemotherapy positron emission tomography/computed tomography imaging. The serum tumor marker (CA-125) level was within the normal range. A correlative magnetic resonance imaging highlighted the diagnosis of mesenteric panniculitis that was also confirmed by clinical follow-up.

18F-Fluorodeoxyglucose Positron Emission Tomography/Magnetic Resonance Imaging Appearance of Gastrointestinal Behcet's Disease.

Behcet's syndrome (BS) is a variable vessel vasculitis with multi-organ involvement. Recurrent episodes of oral and genital ulcers, papulopustular and erythema nodosum-like skin lesions, and arthritis are relatively more frequent, whereas uveitis, venous and arterial lesions, nervous system, and gastrointestinal involvement are less common, but are severe manifestations. The frequency of gastrointestinal involvement shows important variation between countries as more common in the Far East and the United States, and much less common in Turkey and the Middle East. The main clinical signs of gastrointestinal Behcet's disease include abdominal pain, diarrhea, blood in the stool, fever, and weight loss. Ulcers seen in the terminal ileum, cecum, and ascending colon are common endoscopic findings. Herein, we presented the positron emission tomography/magnetic resonance imaging findings of gastrointestinal involvement in BS.

A case of hepatic focal nodular hyperplasia mimicking hepatocellular carcinoma identified on gallium-68-prostate-specific membrane antigen positron emission tomography/computed tomography.

Prostate-specific membrane antigen (PSMA) is a glycosylated type-II transmembrane protein highly expressed in individual tumor cells. Lesions with PSMA expression in the liver are commonly reported as prostate cancer metastasis or hepatocellular cancer previously. This is the first case reported as hepatic focal nodular hyperplasia, mimicking hepatocellular carcinoma with imaging features. This patient, having a lesion that has been enlarged from 2.0 cm to 2.5 cm in 3 months, was referred to our department for restaging by gallium-68 PSMA (68Ga-PSMA) positron emission tomography/computed tomography (PET/CT). The CT scan showed a focal segment VI hypodensity, which was significantly PSMA-avid. Consequently, its biopsy resulted as focal nodular hyperplasia in liver. His follow-up 68Ga-PSMA PET/CT ultimately revealed a mass lesion of 8 cm of axial diameter.

Candida esophagitis incidentally detected by 18F-FDG PET/CT in a patient with CNS lymphoma.

Corticosteroids are commonly used in lymphoma patients, and findings in favor of esophageal involvement in 18F-FDG PET-CT should be considered suspicious and definitely be confirmed by biopsy. We describe a 58-year-old lady with diffuse large B-cell lymphoma and central nervous system involvement having an increased metabolism in the distal esophagus with 18F-FDG PET/CT, which was consistent with esophageal candidiasis, most probably due to prolonged use of dexamethasone. Esophageal candidiasis can be misdiagnosed as malignancy with a high SUVmax and may lead to difficulties while managing these patients.

Evaluation of F-18 DOPA PET/CT in the detection of recurrent or metastatic medullary thyroid carcinoma: comparison with GA-68 DOTA-TATE PET/CT.

OBJECTIVE: PET imaging with F-18 DOPA (FDOPA) and Ga-68 DOTATATE (TATE) shows the most promising results to detect medullary thyroid cancer (MTC) recurrence. We performed this comparative study to detect the site of recurrent or metastatic disease in MTC patients with elevated serum calcitonin (Ctn) and/or carcinoembryonic antigen (CEA) levels. METHODS: We studied 46 MTC patients (25 women, 21 men) with elevated Ctn and/or CEA levels during follow-up who had both FDOPA and TATE PET/CT scans for re-staging purposes. RESULTS: FDOPA PET imaging yielded an overall sensitivity of 86.8%, specificity of 100%, PPV of 100%, NPV of 61.5%, and accuracy of 89.1%, while TATE PET scan had the same values as 84.2%, 87.5%, 96.9%, 53.8%, and 84.6%, respectively, and there was no statistically significant difference between the two modalities with the exception of the specificity value that was higher for FDOPA imaging. In a subgroup of patients with overt Ctn or CEA elevation, sensitivity of FDOPA increased significantly, whereas TATE sensitivity did not change. FDOPA PET imaging was significantly superior in detecting liver and regional lymph node (LN) metastases, while TATE PET scan was significantly better in the skeletal metastases. Early FDOPA demonstrated 11 invisible lesions on late FDOPA. CONCLUSION: Both FDOPA and TATE PET/CT imaging are useful to localize recurrences in MTC patients. While TATE imaging is superior to reveal skeletal disease, FDOPA seems better in liver and regional LN metastases; therefore, the two modalities appear complementary in monitoring MTC patients with elevated serum Ctn and/or CEA levels.