Nuclide Notes

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.

16/02/2026

☢️ Peritoneal lymphoma ☢️ FDG PET/CT shows widespread hypermetabolic peritoneal thickening with extensive omental and serosal studding (peritoneal/omental lymphomatosis pattern), involving the mesentery and abdominopelvic peritoneal reflections, and deposits along the mental ligaments. Hypermetabolic mesenteric and retroperitoneal nodal masses/soft tissue fullness extending into the right perinephric space infiltrating the renal parenchyma. Diffuse hypermetabolic large and small bowel wall thickening. Biopsy showed NHL/DLBC.
🗓 Peritoneal involvement by lymphoma usually appears as diffuse or nodular peritoneal thickening “peritoneal lymphomatosis”, often associated with omental caking, mesenteric soft tissue infiltration, and variable ascites. Unlike peritoneal carcinomatosis, bulky lymphadenopathy and splenic involvement may be present and can provide an important diagnostic clue. On FDG PET/CT, peritoneal deposits are intensely avid, helping define the full extent of serosal disease, distinguish active lymphoma from simple fluid, and identify the most accessible hypermetabolic site for biopsy. Key differentials include peritoneal carcinomatosis, tuberculous peritonitis, and inflammatory peritonitis.

13/02/2026

☢️ Hydroxyapatite crystal deposition ☢️ 54-years-old male patient diagnosed with Non-Hodgkin’s lymphoma in remission, presented with low grade fever, mildly elevated WBC, CRP and thigh pain. FDG PET revealed amorphous hyperdense deposits of mild FDG uptake in the iliofemoral ligament.
🗓 Periarticularcalcific deposits in the tendons and soft tissue is caused by hydroxyapatite crystals deposition within the periarticular soft tissue (mostly tendons), most commonly affect the rotator cuff of shoulder at the supraspinatus tendon insertion. It may affect also the capsules, ligaments and bursae with the hip and knee being other common locations. Increased FDG uptake is most likely due to local inflammation caused by hydroxyapatite crystals deposition. The incidence is 2.5-20% in shoulder and less common in hip. Slightly more frequent in females. Patients present with acute or chronic hip pain, elevated WBC, fever with limitation of movement; however the symptoms depend the phase of clinical presentation.

11/02/2026

☢️ CIED Infection ☢️ FDG PET/CT shows intense FDG uptake involving soft tissue fullness surrounding the pocket device tracking along the proximal leads with regional fat infiltration.
🗓 In suspected CIED infection, FDG PET/CT is a valuable modality when there is suspected infection despite normal echocardiograph, negative cultures, and clinical findings are equivocal. It can localize active infection to generator pocket in the anterior chest wall, and/or along the leads, and provide a whole body assessment for metastatic infectious foci. Overall reported (pooled meta-analysis) SN 83-87% and SP 90-94%.
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10/02/2026

☢️ Sister Mary Joseph nodule ☢️ FDG PET/CT scan shows a hypermetabolic umbilical nodular soft tissue lesion of intense uptake, consistent with metastatic Sister Mary Joseph nodule in a gastric cancer patient.
🗓️ Sister Mary Joseph nodule is a metastatic umbilical soft tissue lesion mostly from a direct peritoneal spread, most commonly from intra abdominal adenocarcinoma. Patients usually present with umbilical lesion that can be painful or asymptomatic, it can also be ulcerating or associated with discharge. The reported incidence is 1-3% of intra abdominopelvic malignancies.