Nuclide Notes

09/03/2026

☢️ Acetabular loosening ☢️ 37-year-old male with total hip replacement 2 years ago complaining of hip pain and skin warmth, his WBC and ESR are elevated. SPECT/CT images show intense tracer uptake in DeLee and Charnley zones I, II and III with corresponding irregular osteolysis and lucencies of more than 2 mm at the bone-prosthesis interface. In the blood pool phase, there is mildly increased vascularity in right proximal thigh subcutaneous soft tissue collection extending to skin thickening. Increased tracer uptake in the intermediate (zone II) in combination with superior and or inferior third is suggestive of loosening in the acetabular cup, in the presence of osteolysis or lucencies of more than 2 mm this is almost certain of loosening.
🗓 Normal tracer uptake is expected up to 2 years post surgery in homogeneous pattern involving the acetabulum, greater trochanter and femoral tip. The diagnostic efficiency of planar bone scan is 85% SN and 72% SP. SPECT/CT improves diagnostic accuracy and better localizes activity to identify typical patterns of uptake for specific pathologies in Total hip replacement. It can also identify other regions in the bone suffering from clinically relevant pathologies whether involving the prosthesis directly or in other regions.
BoneScan

08/03/2026

☢️ Dermal NHL ☢️ FDG PET/CT scan shows hypermetabolic left lower limb broad based fungating dermal soft tissue mass involving the posterior aspect of the distal thigh and proximal leg. Multifocal subdermal thickenings of non to moderate FDG uptake involving the right gluteal fold and bilateral lower limbs. Biopsy revealed NHL/DLBC.
🗓️ Dermal lymphoma is rare and classified into primary cutaneous B cell and primary cutaneous T cell lymphomas. Dermal DLBC is associated with a worse prognosis and higher risk of extracutaneous spread. Usually they present as firm red to violaceous nodules or plaques (sometimes multiple, occasionally ulcerated) and are often FDG-avid.

05/03/2026

☢️ Chronic knee capsulitis ☢️ 60-year-old female with TKR 4 years ago, complaining of stiffness and vague/dull pain around the knee joint. The pain intensifies with prolonged weight bearing. Recent X-ray did not show any abnormality. Biphasic SPECT/CT shows intense tracer uptake at the expected attachments sites (enthesis) of the knee capsule and to a large probable enthesophyte. There was significant pain relief after corticosteroids injections.
🗓 Capsulitis is inflammation of joint capsule can be either primary or secondary as a sequela of traumatic event, infection, or inflammation. The capsule becomes thickened and generally associated with synovitis. Uptake in the attachments site gives rise to “wrapped bone” sign on planar bone scan with prominent uptake at the lateral and retro-condylar insertions and behind the tibial plateau. In chronic capsulitis, enthesophytes are commonly seen.

04/03/2026

🔥 inflammation on FDG PET
Injury/infection → mediators cause vasodilation + leaky vessels + endothelial activation → neutrophils first, then macrophages. These activated immune cells increase glucose use, pull FDG in via GLUT, phosphorylate it via hexokinase, and trap it as FDG-6-P. During phagocytosis, the respiratory burst needs lots of NADPH (PPP pathway) → even higher glucose demand → higher FDG signal.

28/02/2026

☢️ Uveal melanoma ☢️ FDG PET/CT shows hypermetabolic left facial subdermal soft tissue mass centered at the infraorbital region broadly obliterating the palpebral sulcus and medial commissure with subsequent orbital fat obliteration in the supraorbital region with gas locules, contour deformity and supraorbital dermal ulceration. The mass is tracking along the left nasal wing invading the nasal vestibule and further extending inferiorly to the nasolabial sulcus.
🗓️ Uveal melanoma is the most common intraocular malignancy in adults arising from melanocytes (most common) of the choroid, ciliary body or iris. Symptoms presents as blurred vision, photopsia/floaters, visual field defects, or is found incidentally. Prognosis is determined by hematogenous spread predominantly in the liver followed by the lungs and bone, this is why surveillance focuses on liver imaging and function tests. Risk factors include fair skin, caucasian ethnicity, pre-existing choroidal nevus, BAP1 loss.

25/02/2026

☢️ Spinal pseudoarthrosis ☢️ 64-year-old female with history of posterior L3-L4 rigid fixation 17 months ago, complaining of persistent back pain. Perfusion and delayed SPECT/CT images demonstrate L3-L4 lack of significant intersomatic ossification and cage subsidence showing diffuse intense perfusion around the interbody cage and intense delayed tracer uptake corresponding to endplates irregularities and subchondral sclerosis. SPECT + CT+ findings consistent with pseudoarthrosis with probable spondylodiskitis.
🗓️ Pseudoarthrosis is the failure of bone healing after spinal surgery, resulting in a nonunion between the vertebrae that were intended to be fused. The term “pseudoarthrosis” literally translates to “false joint,” indicating that instead of a solid, continuous bone forming through the fused segment of the spine, there is an abnormal movement due to non-fusion. Expected SPECT/CT pattern in pseudoarthrosis is intense uptake with no signs of fusion/persistent clefting.

24/02/2026

🩸 GI Bleed on Scintigraphy: the Basics

• Protocol breakdown
• Labeling efficiencies explained
• Drug interference pearls
• Normal appearance

23/02/2026

☢️ Triple negative IDCa ☢️ FDG PET/CT shows right breast lobular soft tissue mass of intense FDG uptake [SUVmax= 14.1] with regions of cystic degeneration and hemmorhagic content, invading the overlying dermis with contour deformity measuring 9.4X6 cm. There are hypermetabolic regional satellite nodular densities of intense FDG uptake [SUVmax= 11].
🧬 Invasive Ductal Carcinoma (IDC), TNBC

📈 FDG-PET: high FDG uptake.
🧪 HR+ tumors → Often spread to bone (usually osteolytic in case of IDC).
🧪 HR– tumors → High risk for brain metastases.

21/02/2026

☢️ Hepatic squamous cell carcinoma ☢️ There is a large hepatic cystic mass occupying the right lobe with hypermetabolic rim of intense FDG uptake showing internal gas locules, necrotic centers and partially exophyting component. The gallbladder is obstructed with subsequent severe dilatation showing multifocal regions of wall thickenings with at least one focal area is hypermetabolic of moderate FDG uptake.
🗓️ Liver squamous cell carcinoma is a rare subtype of liver cancer, accounting for less than 1% of primary liver malignancies. It has a male dominance with an average age range of 50-60, often associated with hepatic congenital cysts, hepatolisthiasis, teratoma. Presentation varies but commonly includes abdominal pain, weight loss, jaundice, and hepatomegaly. Prognosis is generally poor, with a median survival of less than a year due to its aggressive nature and advanced stage at diagnosis. CT appearance is usually a predominantly cystic mass with heterogeneous arterial enhancement.

19/02/2026

☢️ Humerus osteoid osteoma ☢️ SPECT/CT shows left humeral diaphysis intracortical Lucent lesion with internal central hyperdensity, narrow zone of transition corresponding to intense tracer uptake. There is complete sclerotic rim and periosteal reaction. Findings are consistent with intra cortical osteoid osteoma.
🗓️ Osteoid osteomas comprise 10-12% of all benign osseous neoplasms and 2-5% of all primary bone tumors, its generally a condition of adolescents but it can affect a wide range of individuals 8 months - 70 years, males are affected more than females. The most characteristic clinical presentation is pain (typically deep, aching, and intense), which is worse at night and relieved by aspirin or other nonsteroidal antiinflammatory drugs. In bone scan osteoid osteomas have been described by being positive in all phases. In the early vascular and blood pool phases there is intense flow and blood pool activity, in the delayed phase there is an intense focal uptake and sometimes will show a slightly hotter area within a hot spot (double density sign) which is highly specific for osteoid osteoma.

18/02/2026

17/02/2026

☢️ Cutaneous sarcoidosis ☢️ FDG PET/CT scan demonstrates hypermetabolic subdermal nodular soft tissue densities in the upper limbs, bilateral shoulders and posterior chest wall. Hypermetabolic prominent sized multicompartmental cervical, mediastinal and hilar, multilevel axillary and abdominopelvic lymph nodes. Hypermetabolic nodular infiltration along the superficial bilateral parotid lobes. Bilateral predominantly perilymphatic nodules of non and minimal metabolic activity. Axillary lymph node and subdermal nodular soft tissue density. Biopsies confirmed sarcoidosis.
🗓️ Sarcoidosis is multisystemic disease of unknown etiology characterized by formation of inflammatory noncaseating granulomas. It has a variable age of onset and commonly presents between the 2nd and 4th decades of life. Clinical presentation is variable, about 50% of the patients are asymptomatic and it can affect any organ in the body. Subcutaneous involvement is rare for of cutaneous sarcoidosis (9-30%) and it follow a nodular or diffuse pattern. The nodular pattern is usually well defined nodular densities, the diffuse pattern is characterized by ill-defined honeycomb like soft tissue appearance.