Prevalence of interstitial pneumonia suggestive of COVID-19 at 18F-FDG PET/CT in oncological asymptomatic patients in a high prevalence country during pandemic period: a national multi-centric retrospective study.

PURPOSE: To assess the presence and pattern of incidental interstitial lung alterations suspicious of COVID-19 on fluorine-18-fluorodeoxyglucose positron emission tomography (PET)/computed tomography (CT) ([18F]FDG PET/CT) in asymptomatic oncological patients during the period of active COVID-19 in a country with high prevalence of the virus. METHODS: This is a multi-center retrospective observational study involving 59 Italian centers. We retrospectively reviewed the prevalence of interstitial pneumonia detected during the COVID period (between March 16 and 27, 2020) and compared to a pre-COVID period (January-February 2020) and a control time (in 2019). The diagnosis of interstitial pneumonia was done considering lung alterations of CT of PET. RESULTS: Overall, [18F]FDG PET/CT was performed on 4008 patients in the COVID period, 19,267 in the pre-COVID period, and 5513 in the control period. The rate of interstitial pneumonia suspicious for COVID-19 was significantly higher during the COVID period (7.1%) compared with that found in the pre-COVID (5.35%) and control periods (5.15%) (p < 0.001). Instead, no significant difference among pre-COVID and control periods was present. The prevalence of interstitial pneumonia detected at PET/CT was directly associated with geographic virus diffusion, with the higher rate in Northern Italy. Among 284 interstitial pneumonia detected during COVID period, 169 (59%) were FDG-avid (average SUVmax of 4.1). CONCLUSIONS: A significant increase of interstitial pneumonia incidentally detected with [18F]FDG PET/CT has been demonstrated during the COVID-19 pandemic. A majority of interstitial pneumonia were FDG-avid. Our results underlined the importance of paying attention to incidental CT findings of pneumonia detected at PET/CT, and these reports might help to recognize early COVID-19 cases guiding the subsequent management.

Applications of PET and SPECT in Patients with Autism Spectrum Disorder.

Autism spectrum disorder (ASD) consists of neurological development disorders that manifest before three years of age and affect social interactions, markedly restricting range of interests and activities, often associated with some degree of intellectual disability. Single-photon emission computed tomography (SPECT) and positron emission tomography (PET) are non-invasive imaging tools to investigate the function of the brain in vivo. SPECT and PET studies exploring rCBF and brain glucose metabolism in patients with ASD have been performed, providing important insights into the brain regions involved in ASD. Abnormalities in serotonergic, dopaminergic, GABAergic, cholinergic, and glutamatergic systems have been suggested to contribute to the observed distorted brain circuitry associated with ASD. However, the specificity of such abnormalities needs to be fully clarified because schizophrenia and other psychiatric diseases have been shown to present with comparable changes in neurotransmitter systems. Neuroinflammation could also play a role in the development of autism. Therefore, ASD is a complicated process involving a number of factors. It is mandatory to perform more research studies to determine the molecular cornerstone of ASD and to improve our comprehension of the clinical correlates of ASD.

Early diagnosis of focal congenital hyperinsulinism: A fluorine-18-labeled l-dihydroxyphenylalanine positron emission tomography/computed tomography study.

Congenital hyperinsulinism (CHI) is responsible for hyperinsulinemic hypoglycemia which needs aggressive treatment in order to prevent neurological damages. Recent advances in genetics have linked CHI to mutations in many different genes that play a key role in regulating insulin secretion from pancreatic ß-cells. Furthermore, histopathological lesions, diffuse and focal, have been associated with these different genetic alterations. This short manuscript describes how the advent of fluorine-18-labeled L-dihydroxyphenylalanine-positron emission tomography/computed tomography (18F-DOPA-PET/CT) scanning has changed the management of patients with CHI. 18F-DOPA PET/CT imaging differentiates focal from diffuse disease and is 100% accurate in localizing the focal lesion. In these patients, the lesion can be surgically removed allowing complete resolution of clinical alterations. We report a case in which clinical experience together with rapid genetic analysis and imaging with 18F-DOPA-PET/CT, were able to guide the correct clinical management of this condition. We confirm that advances in molecular genetics, imaging methods (18F-DOPA PET-CT), medical therapy, and surgical approach have completely changed the management and improved the outcome of these children.

Lung cancer metastasis mimicking fingertip osteomyelitis: An 18F-fluorodeoxyglucose positron emission tomography-computed tomography study.

Lung cancer commonly metastasizes to ipsilateral and contralateral lungs, to mediastinal lymph nodes, to skeletal level, to brain, and to adrenal gland. It is indeed very rare to find skeletal metastases at the extremities, especially at the onset of the disease. We share the case of a 53-year-old man with dyspnea and pain at the level of the first finger of the left hand under antibiotic treatment for suspected osteomyelitis. 18F-fluorodeoxyglucose positron emission tomography-computed tomography showed the presence of a left lung lesion with multiple localizations at muscles and bones.

18F-Fluciclovine Positron Emission Tomography in Prostate Cancer: A Systematic Review and Diagnostic Meta-Analysis.

BACKGROUND: to explore the diagnostic accuracy of 18F-Fluciclovine positron-emission tomography (PET) in prostate cancer (PCa), considering both primary staging prior to radical therapy, biochemical recurrence, and advanced setting. METHODS: A systematic web search through Embase and Medline was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies performed from 2011 to 2020 were evaluated. The terms used were "PET" or "positron emission tomography" or "positron emission tomography/computed tomography" or "PET/CT" or "positron emission tomography-computed tomography" or "PET-CT" and "Fluciclovine" or "FACBC" and "prostatic neoplasms" or "prostate cancer" or "prostate carcinoma". Only studies reporting about true positive (TP), true negative (TN), false positive (FP) and false negative (FN) findings of 18F-fluciclovine PET were considered eligible. RESULTS: Fifteen out of 283 studies, and 697 patients, were included in the final analysis. The pooled sensitivity for 18F-Fluciclovine PET/CT for diagnosis of primary PCa was 0.83 (95% CI: 0.80-0.86), the specificity of 0.77 (95% CI: 0.74-0.80). The pooled sensitivity for preoperative LN staging was 0.57 (95% CI: 0.39-0.73) and specificity of 0.99 (95% CI: 0.94-1.00). The pooled sensitivity for the overall detection of recurrence in relapsed patients was 0.68 (95% CI: 0.63-0.73), and specificity of 0.68 (95% CI: 0.60-0.75). CONCLUSION: This meta-analysis showed promising results in term of sensitivity and specificity for 18F-Fluciclovine PET/CT to stage the primary lesion and in the assessment of nodal metastases, and for the detection of PCa locations in the recurrent setting. However, the limited number of studies and the broad heterogeneity in the selected cohorts and in different investigation protocols are limitation affecting the strength of these results.

FDG-PET/CT in the Radiotherapy Treatment Planning of Locally Advanced Anal Cancer: A Monoinstitutional Experience.

AIMS: Radiotherapy with concurrent 5-fluorouracil/mitomycin-C based chemotherapy has been established as definitive standard therapy approach for anal cancer. Intensity Modulated Radiotherapy (IMRT) leads to a precise treatment of the tumor, allowing dose escalation on Gross Tumor Volume (GTV), with a surrounding healthy tissues sparing. Our study assessed the impact of 18-Fluorodeoxyglucose positron emission tomography (18FDG-PET/CT) on the radiotherapy contouring process and its contribution to lymphatic spread detection, resulting to a personalization of Clinical Target Volume (CTV) and dose prescription. METHODS: Thirty-seven patients, with histologically proven squamous cell carcinoma of the anal canal (SCCAC) were analyzed. All patients were evaluated with history and physical examination, trans-anal endoscopic ultrasound, pelvis magnetic resonance imaging (MRI), computed tomography (CT) scans of the chest, abdomen and pelvis and planning 18FDG-PET/CT. The GTV and CTV were drawn on CT, MRI and 18FDG-PET/CT fused images. RESULTS: Thirty-four (91%) out of 37 patients presented lymph nodes involvement, in one or more areas, detected on 18FDG-PET/CT and/or MRI. The 18FDG-PET/CT showed positive lymph nodes not detected on MRI imaging (PET+, MRI-) in 14/37 patients (38%). In 14 cases, 18FDG-PET/CT allowed to a dose escalation in the involved nodes. The 18FDG-PET/CT fused images led to change the stage in 5/37(14%) cases: four cases from N0 to N1 (inguinal lymph nodes) and in one case from M0 to M1 (common iliac lymph nodes). CONCLUSIONS: The 18FDG-PET/CT has a potentially relevant impact in staging and target volume delineation/definition in patients affected by anal cancer. In our experience, clinical stage variation occurred in 14% of cases. More investigations are needed to define the role of 18FDG-PET/CT in the target volume delineation of anal cancer.

State of the art of 18F-FDG PET/CT application in inflammation and infection: a guide for image acquisition and interpretation.

AIM: The diagnosis, severity and extent of a sterile inflammation or a septic infection could be challenging since there is not one single test able to achieve an accurate diagnosis. The clinical use of 18F-fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) imaging in the assessment of inflammation and infection is increasing worldwide. The purpose of this paper is to achieve an Italian consensus document on [18F]FDG PET/CT or PET/MRI in inflammatory and infectious diseases, such as osteomyelitis (OM), prosthetic joint infections (PJI), infective endocarditis (IE), prosthetic valve endocarditis (PVE), cardiac implantable electronic device infections (CIEDI), systemic and cardiac sarcoidosis (SS/CS), diabetic foot (DF), fungal infections (FI), tuberculosis (TBC), fever and inflammation of unknown origin (FUO/IUO), pediatric infections (PI), inflammatory bowel diseases (IBD), spine infections (SI), vascular graft infections (VGI), large vessel vasculitis (LVV), retroperitoneal fibrosis (RF) and COVID-19 infections. METHODS: In September 2020, the inflammatory and infectious diseases focus group (IIFG) of the Italian Association of Nuclear Medicine (AIMN) proposed to realize a procedural paper about the clinical applications of [18F]FDG PET/CT or PET/MRI in inflammatory and infectious diseases. The project was carried out thanks to the collaboration of 13 Italian nuclear medicine centers, with a consolidate experience in this field. With the endorsement of AIMN, IIFG contacted each center, and the pediatric diseases focus group (PDFC). IIFG provided for each team involved, a draft with essential information regarding the execution of [18F]FDG PET/CT or PET/MRI scan (i.e., indications, patient preparation, standard or specific acquisition modalities, interpretation criteria, reporting methods, pitfalls and artifacts), by limiting the literature research to the last 20 years. Moreover, some clinical cases were required from each center, to underline the teaching points. Time for the collection of each report was from October to December 2020. RESULTS: Overall, we summarized 291 scientific papers and guidelines published between 1998 and 2021. Papers were divided in several sub-topics and summarized in the following paragraphs: clinical indications, image interpretation criteria, future perspectivess and new trends (for each single disease), while patient preparation, image acquisition, possible pitfalls and reporting modalities were described afterwards. Moreover, a specific section was dedicated to pediatric and PET/MRI indications. A collection of images was described for each indication. CONCLUSIONS: Currently, [18F]FDG PET/CT in oncology is globally accepted and standardized in main diagnostic algorithms for neoplasms. In recent years, the ever-closer collaboration among different European associations has tried to overcome the absence of a standardization also in the field of inflammation and infections. The collaboration of several nuclear medicine centers with a long experience in this field, as well as among different AIMN focus groups represents a further attempt in this direction. We hope that this document will be the basis for a "common nuclear physicians' language" throughout all the country. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40336-021-00445-w.

Focal cortical dysplasia type 1b as a cause of severe epilepsy with multiple independent spike foci.

To investigate the clinical picture, the neurophysiological pattern, and neuropathological features of a young woman with severe drug-resistant epilepsy of unknown cause. We used the patient's clinical records from the age of 2 to 20years including neurophysiological patterns recorded via both scalp and cortex electrodes and results of studies conducted on the brain neuropathological specimen. The patient, with severe mental/psychomotor retardation, suffered from severe epilepsy from an early age, characterized by daily seizures of multiple types (atypical absences, tonic, and complex partial seizures), high frequency, and intractability. The neurophysiological pattern indicated multiple independent spike foci (SE-MISF). When she was 16, a vagal nerve stimulator was implanted without success. Neither neuroimaging (brain MRI and ictal SPECT) nor surface EEGs identified unique loci of seizure onset, establishing her as a candidate for a complete callosotomy. When the patient was 19, before the callosotomy, invasive EEG (i.e., electrocorticography) using just a few electrodes in different lobes showed the presence of a distinctive pattern. The surgical specimen, taken very close to one of the activity sites, showed architectural abnormalities and neurons that were giant or immature but not dysmorphic, indicative of focal cortical dysplasia (FCD) type 1b. Twelve months after the callosotomy, according to the Engel score, the patient exhibited a large improvement in quality of life, without permanent complications from the interhemispheric disconnection. (1) Hidden FCD type 1b could represent a missing diagnosis in patients with SE-MISF in the absence of other causes for their seizures. (2) Complete callosotomy can be efficacious in patients with SE-MISF with hidden FCD type 1b.

Regional cerebral blood flow in childhood autism: a SPET study with SPM evaluation.

AIM: To establish a link between rCBF assessed with Tc-ECD SPET and the clinical manifestation of the disease. METHODS: We performed the study on 11 patients (five girls and six boys; mean age 11.2 years) displaying autistic behaviour and we compared their data with that of an age-matched reference group of eight normal children. A quantitative analysis of rCBF was performed calculating a perfusion index (PI) and an asymmetry index (AI) in each lobe. Images were analysed with statistical parametric mapping software, following the spatial normalization of SPET images for a standard brain. RESULTS: A statistically significant (P=0.003) global reduction of CBF was found in the group of autistic children (PI=1.07+/-0.07) when compared with the reference group (PI=1.25+/-0.12). Moreover, a significant difference was also observed for the right-to-left asymmetry of hemispheric perfusion between the control group and autistic patients (P=0.0085) with a right prevalence greater in autistic (2.90+/-1.68) with respect to normal children (1.12+/-0.49). Our data show a significant decrease of global cerebral perfusion in autistic children in comparison with their normal counterparts and the existence of left-hemispheric dysfunction, especially in the temporo-parietal areas devoted to language and the comprehension of music and sounds. CONCLUSION: We suggest that these abnormal areas are related to the cognitive impairment observed in autistic children, such as language deficits, impairment of cognitive development and object representation, and abnormal perception and responses to sensory stimuli. Tc-ECD SPET seems to be sensitive in revealing brain blood flow alterations and left-to-right asymmetries, when neuroradiological patterns are normal.

A comparison of 1850 (50 mCi) and 3700 MBq (100 mCi) 131-iodine administered doses for recombinant thyrotropin-stimulated postoperative thyroid remnant ablation in differentiated thyroid cancer.

OBJECTIVE: Recently, a multicenter study in differentiated thyroid cancer (DTC) patients showed that 3700 MBq 131-iodine ((131)I) after recombinant human TSH (rhTSH) had a successful thyroid ablation rate similar to that obtained after thyroid hormone withdrawal. We investigated whether 1850 MBq (131)I had a similar successful rate to 3700 MBq in patients prepared with rhTSH. DESIGN: A total of 72 patients with DTC were randomly assigned to receive 1850 (group A, n = 36) or 3700 MBq (group B, n = 36) (131)I after rhTSH. One injection of 0.9 mg rhTSH was administered for 2 consecutive days; (131)I therapy was delivered 24 h after the last injection, followed by a posttherapy whole-body scan. Successful ablation was assessed 6-8 months later. RESULTS: Successful ablation (no visible uptake in the diagnostic whole-body scan after rhTSH stimulation) was achieved in 88.9% of group A and B patients. Basal and rhTSH-stimulated serum thyroglobulin was undetectable (<1 ng/ml) in 78.9% of group A and 66.6% of group B patients (P = 0.46). Similar rates of ablation were obtained in both groups also in patients with node metastases. CONCLUSION: Therapeutic (131)I activities of 1850 MBq are equally effective as 3700 MBq for thyroid ablation in DTC patients prepared with rhTSH, even in the presence of node metastases.

Prevalence of Paget's disease of bone in Italy.

UNLABELLED: We examined the prevalence of PDB in Italy from radiological, scintigraphic, and biochemical surveys in two Italian towns. Prevalence rates varied from 0.7% to 2.4%, were higher in males than in females, and slightly differed between the two towns. Unlike previous studies in populations of British descent, no secular trend for a decreasing prevalence emerged. INTRODUCTION: Clinical, radiological, and necropsy data from different countries suggested pronounced geographical variations in the prevalence of Paget's disease of bone (PDB). Despite the impact of the disease on the population, there are limited data on the prevalence of PDB in Italy. MATERIALS AND METHODS: The objective of this study was to estimate the prevalence of PDB in the district of Siena (Central Italy) and Turin (Northern Italy) from radiological, biochemical, and scintigraphic surveys. We examined a sample of 1778 consecutive pelvic radiographs performed between 1999 and 2000 at the Hospital Radiology Unit in Siena and 6609 pelvic radiographs performed in 1986-1987, 1992-1993, and 1999-2002 from the Radiology Department of Molinette Hospital in Turin. In Siena, 7906 consecutive (99m)TC-MDP bone scans performed over a 4-year period (January 2000 to May 2004) were also screened for the presence of PDB, and the prevalence of elevated alkaline phosphatase (ALP) levels (>300 UI/liter) was estimated from 7449 computerized medical records over a 3-year period (January 2000 to February 2003). The finding of PDB on the pelvic radiograph and bone scan was based on standardized radiological criteria. RESULTS: At the end of the radiological surveys, 16/1778 pelvic PDB cases (8 males and 8 females) were observed in Siena and 41/6609 (27 males and 14 females) in Turin. The crude prevalence of the disease was 0.89% in Siena and 0.62% in Turin. Given that pelvic involvement is commonly described in 60-90% of PDB patients, the estimated overall prevalence of PDB ranged from 1.0% to 1.5% in Siena and from 0.7% to 1.0% in Turin. No decrease in the prevalence of PDB was evident after comparison of prevalence rates from different periods. Biochemical analyses showed 296/7449 subjects with elevated ALP levels and normal liver enzymes, 87 of whom had confirmed diagnosis of PDB. The estimated prevalence of biochemical PDB was 1.5%. The scintigraphic survey showed a PDB prevalence of 194/7906 (2.4%), which was significantly higher than the radiological and biochemical estimates. CONCLUSIONS: Our surveys suggest that PDB in Italy has an estimated prevalence of at least 1%, comparable with that observed in United States and other European countries, but lower than that described in Britain and New Zealand. No secular trend for a decreasing prevalence of PDB was observed.

Technetium tc 99m-labeled red blood cells in the preoperative diagnosis of cavernous hemangioma and other vascular orbital tumors.

OBJECTIVES: To evaluate technetium Tc 99m (99mTc) red blood cell scintigraphy as a diagnostic tool for orbital cavernous hemangioma and to differentiate between orbital masses on the basis of their vascularization. METHODS: We performed 99mTc red blood cell scintigraphy on 23 patients (8 female and 15 male; mean age, 47 years) affected by an orbital mass previously revealed with computed tomography (CT) and magnetic resonance imaging (MRI) and suggesting cavernous hemangioma. In our diagnosis, we considered the orbital increase delayed uptake with the typical scintigraphic pattern known as perfusion blood pool mismatch. The patients underwent biopsy or surgical treatment with transconjunctival cryosurgical extraction when possible. RESULTS: Single-photon emission tomography (SPET) showed intense focal uptake in the orbit corresponding to radiologic findings in 11 patients who underwent surgical treatment and pathologic evaluation (9 cavernous hemangiomas, 1 hemangiopericytoma, and 1 lymphangioma). Clinical or histologic examination of the remaining 22 patients revealed the presence of 5 lymphoid pseudotumors, 2 lymphomas, 2 pleomorphic adenomas of the lacrimal gland, 1 astrocytoma, 1 ophthalmic vein thrombosis, and 1 orbital varix. CONCLUSIONS: The confirmation of the preoperative diagnosis by 99mTc red blood cell scintigraphy shows that this technique is a reliable tool for differentiating cavernous hemangiomas from other orbital masses (sensitivity, 100%; specificity, 86%) when ultrasound, CT, and MRI are not diagnostic. Unfortunately, 99mTc red blood cell scintigraphy results were positive in 1 patient with hemangiopericytoma and 1 patient with lymphangioma, which showed increased uptake in the lesion on SPET images because of the vascular nature of these tumors. Therefore, in these cases, the SPET images have to be integrated with data regarding clinical preoperative evaluation and CT scans or MRI studies. On the basis of our study, a complete diagnostic picture, CT scans or MRI studies, and scintigraphic patterns can establish the preoperative diagnosis of vascular orbital tumors such as cavernous hemangioma, adult-type lymphangioma, and hemangiopericytoma.

Nuclear medicine imaging of inflammatory/infective disorders of the abdomen.

Different nuclear medicine modalities are currently used to study inflammatory and infective disorders of the abdomen. They are usually complementary to radiology and endoscopy, but they play a pivotal role in particular clinical situations. Several radiopharmaceuticals (e.g., 111In or 99mTc labelled white blood cells, monoclonal antibodies, human polyclonal immunoglobulins, 75Ga citrate) are commercially available, but they can not be used indifferently to study abdominal inflammatory disorders. The lack of comparative studies showing the accuracy of each radiopharmaceutical for the study of inflammatory/infective abdominal diseases does not allow the best nuclear medicine technique(s) to be chosen in an evidence-based manner. To this end we performed a meta-analysis of peer reviewed articles published between 1984 and 2004 describing the use of nuclear medicine imaging for the study of inflammatory bowel disorders, appendicitis and vascular graft infections. A guideline for the optimal radiopharmaceutical(s) to be used in each clinical condition and for different aims is provided.

Cerebral circulation time is prolonged and not correlated with EDSS in multiple sclerosis patients: a study using digital subtracted angiography.

Literature has suggested that changes in brain flow circulation occur in patients with multiple sclerosis. In this study, digital subtraction angiography (DSA) was used to measure the absolute CCT value in MS patients and to correlate its value to age at disease onset and duration, and to expand disability status scale (EDSS). DSA assessment was performed on eighty MS patients and on a control group of forty-four age-matched patients. CCT in MS and control groups was calculated by analyzing the angiographic images. Lesion and brain volumes were calculated in a representative group of MS patients. Statistical correlations among CCT and disease duration, age at disease onset, lesion load, brain volumes and EDSS were considered. A significant difference between CCT in MS patients (mean = 4.9s; sd = 1.27 s) and control group (mean = 2.8s; sd = 0.51 s) was demonstrated. No significant statistical correlation was found between CCT and the other parameters in all MS patients. Significantly increased CCT value in MS patients suggests the presence of microvascular dysfunctions, which do not depend on clinical and MRI findings. Hemodynamic changes may not be exclusively the result of a late chronic inflammatory process.

New-onset hypercholesterolemia as an unusual presenting manifestation of eosinophilic gastroenteritis.

We describe an unusual case of new-onset hypercholesterolemia in a 28-year-old man. The presence of low serum albumin and hypercholesterolemia established the suspicion of gastrointestinal disease. Technetium-99m diethylenetriaminepentaacetic acid scintigraphy was performed to identify possible protein-losing enteropathy. The results were consistent with eosinophilic gastroenteritis, a rare disease characterized by eosinophilic infiltration that may involve several digestive tract layers. To our knowledge, this is the first time that hypercholesterolemia has been recognizing as the presenting manifestation of eosinophilic gastroenteritis. The patient has been successfully treated with prednisone and budesonide. Hypercholesterolemia may be an early manifestation of a serious underlying disease, among which eosinophilic gastroenteritis should also be considered.

Preoperative diagnosis of orbital cavernous hemangioma: a 99mTc-RBC SPECT study.

PURPOSE: This study aimed to describe 99mTc-labeled RBC scintigraphy as a diagnostic method for orbital cavernous hemangiomas and to evaluate this diagnostic tool according to surgical outcomes. METHODS: Fifty-five patients with clinical and radiological (US, CT, and/or MRI) suspicion of unilateral cavernous hemangioma of the orbit underwent 99mTc-RBC SPECT study.Qualitative and semiquantitative evaluations were performed, and results were statistically analyzed. RESULTS: SPECT images showed focal uptake in the orbital mass in 36 of 55 patients. Nineteen patients had a negative scintigraphic pattern, with concordance of early and late absence of uptake of 99mTc-RBC.Our procedure showed 100% sensitivity and 88.9% specificity for the diagnosis of orbital cavernous hemangioma, with a positive predictive value of 90.9% and a negative predictive value of 100%. CONCLUSIONS: 99mTc-RBC imaging is safe, easy to perform, and highly accurate in providing adequate clinical and surgical management. As a noninvasive and highly specific method for diagnosing orbital hemangioma, 99mTc-RBC scintigraphy can avoid more invasive imaging or biopsy.