Osteoid Osteoma (OO) is a frequent benign bone tumor that commonly affects males between 5 and 25. It usually arises from appendicular skeleton involving typically femur and tibia. OOs arising from small bones of hands and feet are very uncommon and metatarsal lesions account for only 1.7%. We report a case of a 20 year-old boy with a long history of nocturnal left foot pain with a good clinical response to assumption of salicylates or nonsteroidal anti-inflammatory drugs (NSAIDs). Plain radiograph of his left showed unconclusive results. Therefore, he underwent a contrast enhanced CT (CECT) scan with multiplanar reconstruction (MPR) that showed a bony lesion in the left third metatarsal bone that was compatible with a nidus even in absence of clear peri-nidal sclerosis. Therefore, other ancillary techniques such as MRI and bone scintigraphy were performed. Conclusive diagnosis was OO of third left metatarsal bone. Our patient underwent a mini-invasive treatment with radiofrequency (RF) ablation. After recovery, our patient had no post-operative complications and showed optimal clinical conditions with complete remission of left foot pain and no change or impairment in walking. In this essay, we discuss key imaging findings of OO of small bones and its treatment with radiofrequency ablation. We describe method of execution and illustrate advantages of this mini-invasive technique. We also perform a review of the literature.

BACKGROUND: Transthyretin amyloid cardiomyopathy (ATTR-CM) can manifest as rhythm disorders, heart failure, but also valvular degeneration. Despite aortic stenosis (AS) being prevalent among the elderly, data on ATTR-CM prevalence and outcome in patients with AS undergoing transaortic valve implantation (TAVI) remain scarce.
OBJECTIVE: To determine ATTR-CM prevalence and evaluate 1-year survival in patients undergoing TAVI.
METHODS: Between December 2020 and September 2021, 100 consecutive patients underwent TAVI and were screened prospectively for ATTR-CM using bone scintigraphy (BS). Monoclonal gammopathy was ruled out in case of cardiac uptake on BS. All patients were followed prospectively for 1year after TAVI.
RESULTS: The proportion of patients aged≥75years or with a EuroSCORE II>8% and possible femoral access was 99%. The abnormal cardiac uptake rate on BS was 7% (95% confidence interval: 2-12%); 86% of these patients were male. The RAISE (remodelling, age, injury, system and electrical) score, indicative of ATTR-CM risk, was higher in case of positive BS (P=0.04). Patients with positive BS were older and exhibited wider QRS complexes on electrocardiography (P=0.003), a higher frequency of reduced LVEF (57% vs. 17%), impaired basal LV strain (P=0.02) and a lower voltage/mass ratio (P=0.01). History of pacemaker implantation before TAVI was higher in the positive BS group (P=0.0004) and remained the only statistically significant factor after adjustment using the Holm-Bonferroni method. One-year survival of patients with positive BS did not differ from that of patients with isolated AS.
CONCLUSIONS: Prevalence of ATTR-CM in patients treated with TAVI, underscoring the need for continued surveillance for potential development of ATTR-CM after TAVI. Caution is warranted regarding the 1-year survival because of the lack of study power. Further investigations are needed to define long-term prognosis of AS with ATTR-CM.

OBJECTIVE: The most widely used staging system for hepatocellular carcinoma (HCC) is the Barcelona Liver Clinic Cancer (BCLC) system, which considers tumor burden, performance status, and liver function. Tumor burden is assessed with cross sectional imaging of the abdomen and chest, controversy surrounds the routine use of bone scintigraphy (BS) for detecting extrahepatic metastases. This study evaluated the role of BS in staging HCC in Mexican patients.
METHODS: Retrospective cross-sectional study of all adults with HCC at a Mexican referral center from 2000 to 2018. Staging included abdominal computed tomography (CT) or magnetic resonance imaging, chest CT, and BS. The main outcome was the impact of BS on staging and/or therapy plans.
RESULTS: Among 238 patients, 2 with fibrolamellar variant and 44 with incomplete data were excluded. Median age was 66 years, 84 % had cirrhosis, and the predominant etiology was hepatitis C virus (43 %). BCLC stages were distributed as follows: A (14 %), B (7 %), C (68 %), and D (11 %). Extrahepatic disease was present in 18 %; only 8 % patients had a positive BS. Among the positive cases, 4 were true positives, but they did not alter staging or therapy plans.
CONCLUSIONS: Routine BS in HCC staging demonstrated low yield, with a notable rate of false positives. Considering the implications of extrahepatic disease, BS may be justified for liver transplant candidates outside conventional criteria. Our study highlights the limited role of BS in early-stage HCC and advocates for a more selective utilization.

OBJECTIVE: Patients who were administered radiopharmaceuticals can be a source of radiation exposure to sonographers. This study aimed to identify factors associated with radiation exposure to breast sonographers from patients administered radiopharmaceuticals for bone scanning.
METHODS: The exposure dose of six sonographers was measured during breast sonography in 59 patients administered 99mTc-HMDP. We predicted the following factors to be related to exposure dose: time interval between administration and sonography, sonography examination time, estimated radioactivity at sonography, sonographer\'s years of experience, and patients\' clinical data (age, renal function and surgical procedure). Spearman\'s rank correlation coefficient was used to examine the relationship between radiation dose and the aforementioned factors.
RESULTS: The mean±standard deviation of the exposure dose for the sonographers was 9.3±3.8 µSv. The time interval between administering the radiopharmaceutical agent and sonography, the sonography examination time and estimated radioactivity at sonography were found to be factors related to the exposure of the sonographer. The exposure dose increased as a function of the shorter time interval, longer examination time and higher estimated radioactivity at sonography.
CONCLUSIONS: The time interval between drug administration and sonography, sonography examination time and estimated radioactivity at sonography contributed to the increased dose to breast sonographers. Although we considered that the exposure dose of sonographers would not possibly exceed the dose limit in the present study, we suggested that radiological technologists need to educate the physicians requesting sonography, and the sonographers about the radiation exposure in nuclear medicine.

Brown tumors, resulting from elevated osteoclast activity, are uncommon skeletal symptoms of hyperparathyroidism. Because of their similar characteristics, it is challenging to differentiate these tumors from multiple myeloma or osteolytic metastases. A 24-year-old female with a painful lump in her left thigh and arm in the past 10 months. The patient reported a history of left femoral bone fracture over a year ago due to low-impact trauma. Plain radiograph images and chest MSCT showed osteolytic lesions at the skull, ribs, and extremities, followed by increased Tc99 bone scan image uptake. Thyroid ultrasound and cervical MSCT showed parathyroid mass. Biochemical and pathologic examination supported the diagnosis of brown tumor. A multidisciplinary approach, including clinical evaluation, biochemical assessment, pathological examination, and advanced imaging modalities such as CT scan, MRI, and bone scintigraphy, is necessary for the differential diagnosis of brown tumors from bone metastasis. Medical history, PTH, calcium levels in the blood, and additional systemic symptoms can all be used to help distinguish between the 2 disorders. The clinical presentation and imaging findings of brown tumors may mimic bone metastasis, necessitating comprehensive evaluation. Multidisciplinary collaboration plays a vital role in reaching an accurate diagnosis. Increased awareness of brown tumors as a potential mimic of bone metastasis may help prevent misdiagnosis and ensure optimal care for patients presenting with osteolytic bone lesions associated with hyperparathyroidism.

OBJECTIVE: We aimed to develop a nomogram able to predict treatment failure, skeletal events, and overall survival (OS) in patients with castration-resistant prostate cancer with bone metastases (CRPC-BM) treated with Radium-223 dichloride (223Ra).
METHODS: Patients from the Castilla-La Mancha Spanish region were prospectively included in the ChoPET-Rad multicenter study from January 2015 to December 2022. Patients underwent baseline, interim, and end-of-treatment bone scintigraphy (BS) and 18F-Fluorocholine PET/CT (FCH PET/CT) scans, obtaining multiple imaging radiomics as well as clinical and biochemical variables during follow-up and studying their association with the previously defined end-points. Survival analysis was performed using the Kaplan-Meier method and Cox regression. Multivariate logistic and Cox regression models were calculated, and these models were depicted by means of nomograms.
RESULTS: Median progression-free survival (PFS) and OS were 4 and 14 months (mo), respectively. The variables that showed independent and significant association with therapeutic failure were baseline alkaline phosphatase (AP) levels (p = 0.022) and the characteristics of BM on the CT portion of PET/CT (p = 0.017). In the case of OS, the significant variables were therapeutic failure (p = 0.038), the number of lines received after 223Ra (p < 0.001), average SUVmax (p = 0.002), bone marrow infiltration in FCH PET/CT (p = 0.006), and interim FCH PET/CT response (p = 0.048). Final nomograms included these variables, showing good discrimination among the 100 patients included in our study. In the study of skeletal events, only OS showed a significant association in the multivariate analysis, resulting in an inconsistent nomogram design.
CONCLUSIONS: FCH PET/CT appears to be a good tool for evaluating patients eligible for treatment with 223Ra, as well as for their follow-up. Thus, findings derived from it, such as the morphological characteristics of BM in the CT, bone marrow infiltration, or the response to 223Ra in the interim study, have proven to be solid and useful variables in the creation of nomograms for predicting therapeutic failure and OS.

OBJECTIVE: Bone scintigraphy is key to non-invasively diagnosing wild-type transthyretin (ATTRwt) amyloidosis, and is mainly used to assess cardiac radiotracer uptake. However, extracardiac radiotracer uptake is also observed. We investigated whether intensity of soft tissue radiotracer uptake is associated with amyloid load in subcutaneous abdominal fat tissue and with mortality.
METHODS: This prospective cohort study included 94 ATTRwt amyloidosis patients and 26 amyloid-negative heart failure controls who underwent whole-body [99mTc]Tc-hydroxydiphosphonate scintigraphy. Site-to-background ratios were calculated for heart, elbows, subcutaneous tissue, shoulders and wrists on anterior planar bone scintigraphy images using rib and whole-body radiotracer uptake as background. Fat tissue aspirates were stained with Congo red to grade amyloid load. Site-to-rib ratios were compared between ATTRwt amyloidosis patients and controls, and associations of site-to-background ratio with Congo red score and all-cause mortality were studied.
RESULTS: ATTRwt amyloidosis patients had higher soft tissue-to-rib, heart-to-rib and heart-to-whole body ratios compared with controls. The intensity of soft tissue uptake was positively associated with amyloid load in fat tissue in ATTRwt amyloidosis patients. Estimated glomerular filtration rate, N-terminal brain natriuretic propeptide, high-sensitivity cardiac troponin T (hs-cTnT), and the prognostic Mayo and NAC staging system were associated with all-cause mortality in univariable models. Soft tissue/rib ratio, hs-cTnT and the prognostic staging systems were the only two variables that were independently associated withall-cause mortality.
CONCLUSIONS: Soft tissue radiotracer uptake on bone scintigraphy in ATTRwt amyloidosis patients is positively associated with amyloid load in abdominal fat tissue and is independently associated with mortality.

Extravasation of 99mTc-labeled radiopharmaceuticals is generally considered to require no specific intervention. In the presented case, the use of hyaluronidase could have minimized the adverse effects resulting from such an extravasation. Currently, no guidelines exist regarding the use of hyaluronidase after extravasation of [99mTc]Tc-HDP. Considering the low risk of administering hyaluronidase, it should be considered to limit the risk of injury after extravasation of [99mTc]Tc-HDP.

BACKGROUND: Aortic stenosis (AS) and transthyretin (ATTR) cardiac amyloidosis (CA) share the same clinical profiles and cardiac phenotype. Amyloid deposits have been frequently reported in aortic valves of patients with severe AS referred for surgical aortic valve replacement (SAVR). The aim of this study was to determine the clinical and myocardial status of patients with aortic valve amyloidosis after aortic valve surgery.
RESULTS: We performed a retrospective descriptive study of 46 patients who underwent SAVR for severe AS with amyloid deposits upon histological analysis. All patients were screened for cardiac involvement. Amyloid deposits typing was successful in 35 (76%) patients and 28 (80%) were ATTR. Two (4%) had positive bone scintigraphy and among the 5 myocardial biopsies performed during surgery, 80% were positive for ATTR deposits.
CONCLUSIONS: ATTR is the predominant type in the presence of amyloid deposits on the aortic valve after surgery for severe AS but is only rarely accompanied by cardiac uptake on bone scintigraphy. Early stages of myocardial involvement are frequent and myocardial biopsy is more sensitive for detection of mild amyloid deposits than bone scintigraphy.

Asymmetric hot spots in the axial skeleton on bone scintigraphy may confound diagnosis. We describe an unexpected artifact of 99mTc-methylene diphosphonate near the breast in a 55-y-old woman with breast cancer. The initial whole-body bone scintigraphy revealed a solitary focal lesion in the anterior ribs on the left side. After careful tracking, we determined that this hot spot originated from the adhesive bandage. The patient had placed it in her left front pocket after removing it from the injection site. She was rescanned after the bandage had been removed from her pocket.