Suspected bone metastases

ACR AC Metastatic Bone Disease; EANM bone scintigraphy

A survey question: is there skeletal disease anywhere. Bone scintigraphy remains the standard whole-skeleton survey for most solid tumours, with anatomical imaging used to characterise what it finds. The trap is a request that is really about cord compression, which is urgent and needs MRI.

Known or suspected malignancy with bone pain, an unexplained rise in alkaline phosphatase or tumour marker, or a suspicious focus on another study.

Referenced decision support — confirm against your local protocol.

Decision support, not a directive. Protocols and timings shown are typical published ones — your local protocol takes precedence, and the vetting radiologist decides.

The request in front of you

Everything is optional. Leave a field alone and the answer assumes nothing — the verdict updates as you go.

Study requested

What the referrer actually asked for. It is evidence of intent, not a constraint on the right answer.

Contrast as written

What the request form says, not what it should say.

Age

Pick a band, or type an exact age if it matters.

years

Pregnancy status

Red flags

These accumulate rather than exclude. Back pain with one of these is a different question from back pain.

Cord features

Weakness, a sensory level, hyperreflexia, sphincter or gait disturbance. This changes how much of the spine is imaged, not which scanner is used — a sensory level says the cord is involved but not reliably where, and the lesion is often several segments higher.

Renal risk factors

The question a vetter can actually answer from the request. An explicit “none known” is a real answer, and it removes checks rather than deferring them.

Previous contrast reaction

The pathway — tap anything already done

Marking a study complete moves the answer on. A patient arrives partway through a pathway far more often than at the start of one.

Accept as requested

Bone scintigraphy — whole body (± three phase)

Bone scintigraphy

What we'd amend, and why

Diphosphonate uptake tracks osteoblastic turnover, so a whole-skeleton survey is obtained in one acquisition at modest cost and dose. That is the right shape of test when the question is distribution rather than characterisation. The flow and blood-pool acquisitions are added only when infection is in the differential; for a pure metastasis survey the delayed whole-body images are what is needed.

Nothing needs resolving before this goes ahead. Routine checks below are owned downstream.

How was this decided?

pathwaystandard — Adults — skeletal survey for metastases
rulerule-pregnancy-ionising — Pregnancy status before an ionising exposure; checked by Radiographer at the scanner

Decision support only. Local protocol takes precedence.

Handled at the scanner(1)nothing for you to do

Settled and owned downstream. Each returns to a radiologist only on the stated trigger.

Pregnancy status before an ionising exposure
Make the pregnancy enquiry immediately before the exposure and record the answer. In the UK this is a statutory operator duty discharged at the time of exposure under the employer’s written procedures required by IR(ME)R 2017 — it is not something the vetting radiologist can perform or pre-empt, and a request is complete without it.
Radiographer at the scannerAt the scanner
Flags back if: The patient states that she is, or may be, pregnant AND the uterus is in or near the primary beam. The exposure is then paused for re-justification by the IR(ME)R practitioner before it proceeds.

Pathways

Big forks are separate pathways; the first whose conditions match is the one used.

Neurological signs — suspected metastatic spinal cord compression

Role	Study & protocol	Why this answers the question
First line	MRI Whole Spine MRI Whole Spine — suspected metastatic cord compression usually appropriate	This is no longer a survey question and it must not be booked like one. Back pain with weakness, a sensory level, gait disturbance or sphincter disturbance in a patient with known or suspected malignancy is metastatic spinal cord compression until MRI says otherwise, and the outcome that is being protected is walking: the single best predictor of ambulatory status after treatment is ambulatory status before it, so hours matter and a scan that waits for a routine slot has already cost some of the benefit. The standard is MRI of the whole spine within 24 hours of the suspicion being raised, and sooner where the deficit is progressing. Whole spine, not the painful level: multiple levels of compression are common, the sensory level is an unreliable localiser and the compressive lesion is frequently several segments higher than the pain. Sagittal T1 plus a fluid-sensitive sequence across every station finds the marrow disease, sagittal T2 shows the degree of thecal and cord deformity, and axial sections through each significant level define circumferential extent for whoever operates or plans the radiotherapy field. The study is unenhanced — gadolinium is added only if infection, an intramedullary lesion or leptomeningeal disease is in the differential — so renal function is not a reason to delay it. Two things do not wait for this scan: dexamethasone, and the call to acute oncology, clinical oncology or spinal surgery. A bone scan cannot answer this question in either direction, and a negative one must never be used to stand it down.
Second line	Bone scintigraphy Bone scintigraphy — whole body (± three phase)	The burden survey the request originally asked for, and it keeps its value — once the cord question has been answered. Distribution of skeletal disease still informs systemic treatment and identifies other sites at risk of fracture. What it cannot do is come first here: osteoblastic uptake says nothing about the canal, and a scan that reports "no significant abnormality" in a patient with an epidural soft-tissue mass is a false reassurance the referrer will act on.

Entered from cord features or a progressive neurological deficit recorded on the request. Nothing here is required — leave those facts unset and the card behaves exactly as it did before, which is the point: this arm sharpens the answer when the referrer tells us, and never withholds one when they do not.
The imaging is not the intervention. Dexamethasone and the referral to acute oncology or spinal surgery are started while the scan is being arranged; a pathway that reads as "scan then treat" loses the hours this diagnosis is measured in.
A patient who cannot have MRI at all — a non-conditional device, or one who cannot lie flat — is not a patient who gets a bone scan instead. CT of the relevant spinal segments with reformats, or CT myelography, is the substitute, and the urgency is unchanged.

Adults — skeletal survey for metastases

Matches your inputsDefault

Role	Study & protocol	Why this answers the question
First line	Bone scintigraphy Bone scintigraphy — whole body (± three phase) usually appropriate	Diphosphonate uptake tracks osteoblastic turnover, so a whole-skeleton survey is obtained in one acquisition at modest cost and dose. That is the right shape of test when the question is distribution rather than characterisation. The flow and blood-pool acquisitions are added only when infection is in the differential; for a pure metastasis survey the delayed whole-body images are what is needed.
Second line	Limb radiograph Limb radiograph — two orthogonal views	The correct next step for a solitary equivocal focus in a long bone: radiographs distinguish a degenerative or post-traumatic cause from lytic destruction, and quantify the cortical involvement that determines fracture risk and whether prophylactic fixation is needed.
Reasonable alternative	Whole-Body MRI Whole-Body MRI — metastatic disease and cancer predisposition surveillance	Displaces scintigraphy where the disease is marrow-based rather than osteoblastic — myeloma, and bone-dominant advanced prostate cancer — and where serial imaging in a younger patient makes cumulative radiation the limiting factor. Diffusion-weighted whole-body imaging detects marrow infiltration before any osteoblastic response exists to be imaged.
Problem solving	MRI Whole Spine MRI Whole Spine — suspected metastatic cord compression	The escalation whenever neurology enters the history. It answers a different question — is the cord compressed — on a different timescale, and no bone scan finding either excludes or establishes it.

Pitfalls

Accepting a bone scan request when the history contains weakness, sensory change, gait disturbance or sphincter disturbance. That is metastatic spinal cord compression until proven otherwise: whole-spine MRI within 24 hours of the suspicion, sooner if the deficit is progressing, with dexamethasone and the acute oncology or spinal surgical referral started in parallel rather than after the report. A bone scan neither excludes it nor localises it.
Imaging only the painful level. Multiple levels of compression are common and the sensory level is an unreliable localiser — a regional study cannot exclude a second compressive lesion, which is why the coverage is whole-spine.
Using scintigraphy to survey myeloma, where lytic lesions can be photopenic and the scan is falsely reassuring.
Reading symmetrical uptake in the spine and pelvis of an older patient as metastatic when it is degenerative — the pattern, not the intensity, carries the information.
Calling a superscan normal. Diffusely increased skeletal uptake with faint or absent renal activity is extensive metastatic disease, not a technically good study.
Failing to explain that treatment-induced flare will make the next scan look worse before it looks better.

Priors — what to pull first

Compare with any previous bone scan before calling new disease: the flare phenomenon after starting effective treatment produces increased uptake in healing metastases and mimics progression for several months.
Pull recent radiographs of the painful site — the explanation is frequently already there.

What makes a good request

Any neurological symptom or sign with back pain in a cancer patient changes the question entirely: that is suspected metastatic spinal cord compression and needs urgent whole-spine MRI, not a bone scan. The standard is MRI of the WHOLE spine within 24 hours of the suspicion being raised, and sooner where the deficit is progressing — and the scan does not gate the treatment. Dexamethasone and referral to the acute oncology, radiotherapy or spinal surgical service run in parallel with booking the scan, not after the report. This card forks on that fact rather than merely mentioning it.
Bone scintigraphy is sensitive and unspecific. It reports osteoblastic response, so degenerative change, healed trauma and infection are all positive, and correlation with anatomical imaging is normally required before a focus is called metastatic.
Two tumour groups behave differently and should not be surveyed by scintigraphy: myeloma, which is lytic and often photopenic, and advanced prostate cancer, where whole-body MRI and PSMA PET both outperform bone scanning.

Scoring this once it is done

The classification and risk tools this question ends in.

SINS (Spinal Instability Neoplastic Score)Bone-RADS (Bone Lesion Scoring)RECIST 1.1 Tumor Response

How these studies are acquired

Contrast, phases and timing for every study on the pathways above.

MRI Whole Spine — suspected metastatic cord compression Bone scintigraphy — whole body (± three phase)Limb radiograph — two orthogonal views Whole-Body MRI — metastatic disease and cancer predisposition surveillance

Confirm locally

Bone scintigraphy — whole body (± three phase): timings are typical — confirm against local protocol.
Timings, contrast volumes and rates above are typical published values. Your department's protocol, scanner and patient population decide the actual numbers.
Safety thresholds and premedication policy follow local policy where it differs from the cited guidance.

References

Implemented from the cited published sources. Educational and workflow support only; confirm against current guidelines and local policy before clinical use.