Nuclide Notes

22/12/2025

☢️ Ulnar fixation infection ☢️ The early and delayed SPECT/CT images demonstrate metallic hardware spanning the proximal left ulnar shaft. There is left proximal forearm antebrachial fascia superficial and subdermal thickening and fat infiltration corresponding to diffuse intense perfusion tracking along the fixation plate and olecranon process of left ulna. There is intense delayed tracer uptake involving the left ulnar olecranon process and proximal fixation screws. Hardware infection and bone infection were confirmed intraoperatively.
🗓️Hardware infection develops when the bacteria adheres to metalwork and form a biofilm. Clinically presents as pain, swelling, erythema. On bone scintigraphy/SPECT/CT, infection is suggested by a hyperemic pattern on early phase, with focal or intense delayed uptake at the bone–prosthesis interface or screws in the delayed phase. Prompt tracer asymmetry in the early frames of the dynamic phase supports infection. CT correlation (fat infiltration, fascial thickening, soft tissue collection, periosteal reaction, lucencies, bone destruction) increases confidence.

20/12/2025

☢️ Tuberous sclerosis ☢️ on CT quick spotters: Brain with subependymal nodules (coarse calcifications), cortical/subcortical tubers ± calcification, and SEGA at/near the foramen of Monro; Chest showing diffuse thin-walled cysts of LAM; Kidneys with multiple bilateral angiomyolipomas containing macroscopic fat and renal cysts (watch for acute hemorrhage); Liver/Spleen may show extra-renal AMLs/cysts; Bones with sclerotic enostoses; Heart with classic rhabdomyomas and especially in adults focal intramyocardial macroscopic fat foci.

19/12/2025

☢️ Pancreatic neck NET ☢️ 18F-NOTA scan demonstrate relatively hyperdense soft tissue lesion of intense FOC uptake in the pancreatic neck, consistent with biopsy proven NET. The remainder of pancreatic parenchyma demonstrate low grade physiological FOC uptake.
🗓️ Pancreatic NET are 40% non functioning, 60% functioning, may secrete several peptide hormones leasing to diverse symptoms. Insulinomas are small benign and functioning, gluconomas cause DM and rash (necrolytic migratory erythema), vipomas are large tumors commonly associated with metastases at time of diagnosis, gastrinomas are less than intestinal carcinoids but usually malignant. ACTH/GHRH/PTHrP/SS are rare and difficult to diagnose.

17/12/2025

How to describe a cavitary lung mass on FDG PET/CT (quick reporting checklist 🫁🔥)

When you see a cavitary lung mass on PET/CT, don’t just say “FDG-avid cavity.” Describe it like this:

✅ Where + size: lobe/segment, maximum dimension (MPR)
✅ Cavity morphology: single vs multiloculated, wall thickness (thin/thick/intermediate), smooth vs irregular, inner margin (shaggy/nodular)
✅ Content: air–fluid level? debris? intracavitary soft-tissue component?
✅ FDG pattern: rim/wall uptake vs intracavitary uptake, focal nodular “hot spot,” SUVmax
✅ CT behavior: spiculation, pleural tags, chest wall invasion, necrosis, bronchial obstruction/atelectasis, surrounding GGO/consolidation, regional satellite nodules
✅ Most helpful line: malignancy vs infection/inflammation clues

Save this for your next lung case ✅

16/12/2025

❓Which of the following statement is true when a LEHR (low energy high resolution) collimator is used instead of HE (high energy) collimator in imaging I131 whole body scan?

15/12/2025

☢️ Paget disease ☢️ 46-year-old female diagnosed with metastatic breast tumor, previously reported as metastatic lesions in the sternum, spine and left pelvic bone. On serial imaging all the lesions were almost resolved after treatment except for the left pelvic lesion. She was referred to do a third follow up whole body bone scan after her last CTx cycle. There is still persistent activity in the left iliac bone and acetabulum which did not change in intensity or pattern of involvement. Fused SPECT/CT images revealed intense uptake in coarse trabeculations and cortical thickening of the left iliac bone, features of paget disease. Biopsy confirmed Paget disease.

14/12/2025

☢️ Appendicitis and contained perforation ☢️ The appendix appears distended and edematous along its course with regional fat infiltration approaching the midline mesentery. Adjacent to distal end and partially encasing the appendix, there is an intra peritoneal hypermetabolic mass like lesion characterized by intermixed fat and soft tissue densities with surrounding clustered subcentimetric rounded lymph nodes not showing significant FDG uptake. There is significant mesenteric surrounding fat infiltration. Following treatment with IV antibiotics surgical appendectomy was performed.

10/12/2025

05/12/2025

☢️ ATFL injury ☢️ 14-year-old football player with prior treated ankle sprain and persistent pain, referred for suspected stress fracture. The perfusion SPECT/CT images demonstrate increased perfusion in a linear pattern at the left anterior malleolar tip extending through soft tissue fullness to the lateral talus at the expected site of attachment of the anterior talofibular ligament. The delayed SPECT/CT images shows increased tracer uptake at the lateral aspect of left talus at the site of ATLF enthesis. There is asymmetrical perfusion and delayed tracer uptake at the epiphyseal growth plates marked in the left side. Findings are consistent with left anterior talofibular ligament persistent injury and enthesitis. Asymmetric in activity between the growth plate can be explained by: 1. Transient or subclinical injury 2. Overuse or stress 3. Physiological asymmetry 4. Asymmetrical growth or development.
🗓️ An Anterior Talofibular Ligament (ATFL) injury is a common type of ankle injury that typically occurs when the ligament is stretched, torn, or sprained. SPECT/CT is of value in mistreated patients or with non resolving pain, either identifying other causes or if there is persistent injury. Intense tissue perfusion in the blood pool phase and corresponds in site to the ligament. The delayed images show variable degrees of uptake and may or may not correspond to osseous changes at the ligament attachments depending if there is associated enthesitis.

04/12/2025

🎯 Axillary lymph node levels are defined by their relationship to pectoralis minor (not the breast, not the axillary vein):
Level I – “Low axilla”: Lateral / inferolateral to pectoralis minor.
Level II – “Mid axilla”: Directly deep / posterior to pectoralis minor .
Level III – “Apical axilla”: Medial / superomedial to pectoralis minor, toward the thoracic inlet.

03/12/2025

☢️ Osteoma ☢️ FDG PET/CT shows a broad based ovoid shaped, dense “ivory-like” lesion arising of the outer surface of the skull without FDG uptake. Features consistent with osteoma.
🗓️ Osteomas are benign lesion often encountered in the skull and sinuses, composed of lamellar/cortical bone. They are slow growing and painless, identified accidentally in scans. Multiple osteomas are associated with Gardner syndrome. On bone scintigraphy they may show mild to moderate tracer uptake.

01/12/2025

☢️ Rheumatoid arthritis ☢️ FDG PET/CT shows symmetric, intense periarticular and joints capsule FDG uptake in both hips, shoulders and knees with joint effusions but no erosions or subchondral changes, in keeping with active synovitis rather than structural damage. Mild FDG uptake along the ACL with subtle fat infiltration. Soft tissue swelling and diffuse FDG uptake along the bilateral foot and ankle ligaments (tenosynovitis/tendinitis) extending to sites of insertion (enthesitis). Mild FDG uptake in the ATFL ligament marked in the right side and within the synovial recesses of ankle.
🗓️ FDG PET/CT can map and quantify active inflammation in rheumatoid arthritis by surveying osteoarticular (bone & soft tissue involvement such as bursa, enthesis), systemic disease involvement (large vessel vasculitis, pulmonary and other organs involvement) and associated complications. Semiquantification and visual assessment can be used to monitor response to therapy, escalation, tapering therapy and identify treatment related complications.