Bone Scintigraphy

What it does

Bone Scintigraphy reads whole-body Tc-99m bisphosphonate scans, still the workhorse exam for skeletal metastases from prostate and breast cancer, for occult fractures and for unexplained bone pain. Upload the anterior and posterior whole-body views, with SPECT/CT of a region when one was acquired; the run detects hotspots across the skeleton and assigns each to an anatomical region.

It returns a metastasis likelihood for each region, a lesion count and the Bone Scan Index, the percentage of skeletal mass involved by tumour. With a prior scan, new lesions are matched and the PCWG3 "2+2" progression rule is applied. Every scan is also checked for myocardial tracer uptake, an incidental sign of transthyretin cardiac amyloidosis (ATTR-CM) that is easy to overlook on an oncology read.

Intended use

Decision support for the high-volume bone-scan list, often reported by general radiologists: a structured hotspot map to check against the images, a quantitative tumour-burden index to follow, and a consistent progression call in prostate cancer trials and clinics. Degenerative change, fractures, injection-site and urinary contamination, flare after therapy and the superscan pattern are the classic traps; every hotspot carries its region and metastasis likelihood.

Who it is for

Nuclear-medicine physicians and radiologists reporting bone scans; urologists and oncologists following metastatic prostate and breast cancer; cardiologists who receive the cardiac-uptake flag.

Accepted input

• Whole-body planar scan: DICOM NM whole-body anterior and posterior views, typically about 256 × 1024 pixels per view.
• SPECT or SPECT/CT (optional): tomographic images of a region to characterise equivocal hotspots.
• Prior bone scan (optional, in prior_files): enables the progression section.

Requirements

Requirement	Why
Both anterior and posterior whole-body views	Hotspots are localised and counted on the paired views
The whole skeleton in the field of view	Regional assignment and the skeletal-mass denominator of the Bone Scan Index
Original DICOM NM images, not screen captures	Count-based quantification and hotspot detection
Prior scan as whole-body views	Lesion matching and the PCWG3 rule

Optional context

The primary tumour, current treatment and the date therapy started can be passed in clinical_context; the treatment timeline matters for distinguishing flare from progression in the guidance.

The result

Section	Content
Metastases	Hotspots with anatomical region, metastasis likelihood per region and total lesion count
Bone Scan Index	Percentage of skeletal mass involved by tumour
Progression versus prior (PCWG3)	New lesions versus the prior scan and a progression call under the PCWG3 "2+2" rule
Incidental cardiac uptake	Myocardial uptake flag with a Perugini-style grade suggesting ATTR-CM
Draft report	Opt-in (options.report): an English narrative that interprets the result for the reader (findings, impression, limitations); every number is checked against the findings

Standards

• Guideline: EANM bone scintigraphy guideline (2016).
• Quantification: Bone Scan Index as the percentage of skeletal mass involved.
• Progression: Prostate Cancer Working Group 3 (PCWG3) "2+2" rule for new bone lesions.
• Cardiac uptake: Perugini grade for myocardial uptake relative to bone.
• DICOM: SR TID 1500 Measurement Report for hotspots and the index; Key Object Selection of the views with flagged regions; Encapsulated PDF.

The PCWG3 "2+2" rule

The rule applies to prostate cancer. On the first follow-up scan after a treatment change, two or more new lesions count as progression only when the next follow-up scan shows at least two further new lesions. The rule exists because a flare response can make existing lesions appear new or more intense; the result reports the counts behind every progression call.

Related models

• nm/cardiac: a dedicated PYP, DPD or HMDP study with H/CL ratio and SPECT, the next step after a cardiac-uptake flag.