A standard breathing test gives one overall number. A VQ SPECT-CT does something different — it maps how well each part of each lung is working separately. For patients told their lung function is borderline for surgery, the regional picture often changes the answer. Dr Lawrence Okiror routinely uses VQ SPECT-CT in his emphysema and lung cancer practice and arranges the scan at Guy's and St Thomas' for private patients (PMI or self-pay). Private appointments at London Bridge Hospital and The Lister Chelsea within 2–3 working days. Self-referrals welcome.
Last reviewed: May 2026 · Dr Lawrence Okiror FRCS(CTh) FRCSEd(CTh) · GMC 6150382
Spirometry gives one overall figure. VQ SPECT-CT shows which parts of which lung are doing the work — and which parts are not. That regional picture is what determines safety, not the single number.
A poor breathing test does not end the surgical conversation. It starts the next set of tests. In NICE NG122, borderline lung function triggers regional functional imaging — not refusal.
Pre-operative SPECT-CT plans the resection. Intra-operative ICG and Firefly infrared imaging verify it. For every segmentectomy — and for sublobar resection in borderline patients — the regional map is carried into the operation.
Spirometry — blowing as hard as you can into a tube — gives one number for each lung: FEV1, the volume of air moved in the first second. It is a useful measurement and it is the right place to start. But it has a structural limit. It cannot distinguish the lung that is genuinely working from the lung that is doing nothing.
For patients with even lung disease across both sides, one number is a reasonable summary. For patients whose lungs are unevenly damaged — emphysema concentrated in the upper lobes, scarring in one segment, a tumour sitting in destroyed lung — the single number under-estimates the lung that remains functional. The destroyed part is dragging the overall figure down. Removing it may not reduce overall function at all.
This is the point at which a regional functional scan changes the answer. For an overview of how this fits the whole fitness picture, see Fitness for Lung Surgery →
Which part of which lung the number is coming from. Whether the area that would be removed by surgery is contributing 5% of function or 25%. Whether the lung left behind would be enough.
A VQ SPECT-CT combines three pieces of information into one map. First, ventilation (V): a small amount of inhaled tracer shows which parts of the lung are receiving air. Second, perfusion (Q): an injected tracer shows which parts are receiving blood. Third, a CT image of the chest gives the anatomical map underneath. The three together show, region by region, the proportion of total lung function each segment contributes.
For a surgeon planning a lung cancer operation, this answers the question that spirometry cannot. If the segment containing the tumour is contributing 5% of total function, removing it costs almost nothing. If it is contributing 20%, the calculation is different — and the operation has to be planned around it. The scan often supports surgery in patients told elsewhere they were not fit. It also sometimes confirms that the operation is not safe, which is part of what the scan is for. It is a decision tool, not a permission slip.
The scan is painless. It takes around 30–45 minutes total. There is no significant preparation. Radiation dose is comparable to a standard CT thorax.
Private patients are scanned at Guy's and St Thomas' through an established private patient pathway — PMI or self-pay. The same scanner and reporting team that supports the NHS lung cancer and lung volume reduction programmes.
VQ SPECT-CT is routine in lung volume reduction surgery. It is how the diseased lung is identified, how the target segments are chosen, and how the planned operation is mapped before the patient enters theatre. Dr Okiror has used the scan as the planning instrument across more than 100 emphysema interventions since 2019 at Guy's and St Thomas'.
That same regional discipline now anchors his lung cancer practice. For borderline-fitness patients, the SPECT-CT decides whether surgery is safe and which operation gives the right balance of cancer clearance and preserved function. For fit patients undergoing precision segmentectomy, it confirms that the segment being removed is contributing less than the lung being preserved. For the rare patient whose cancer sits inside emphysematous lung, it informs whether a combined cancer-and-lung-volume-reduction operation would improve breathing as well as treat the cancer.
Very few thoracic surgeons in the UK use functional imaging across both their cancer and emphysema practice. The cross-pollination is the point: the same technique that maps destroyed lung in emphysema maps preserved lung in cancer.
Indocyanine green (ICG) is a fluorescent dye given through a vein during the operation. The da Vinci robotic system has an infrared camera called Firefly that visualises ICG in real time. When the segmental arteries supplying the part of the lung being removed are clamped, the rest of the lung — the part being preserved — lights up green. The lung that has lost its blood supply remains dark. The intersegmental plane is visible to the surgeon, not estimated.
Dr Okiror uses ICG and Firefly during every robotic segmentectomy, regardless of lung function. For patients with borderline lung function having a sublobar (smaller-than-lobectomy) resection, the same intra-operative perfusion check is used routinely. The reason is the same in both: confirming that the lung being preserved is genuinely perfused and functional changes the resection plan in a meaningful minority of cases.
For more on the robotic platform and the visualisation systems used during surgery, see Robotic Lung Surgery →
When every preserved millilitre of functional lung counts, an intra-operative check that the lung being kept is genuinely working is not a luxury. It is the difference between a planned operation and a verified one.
Patients with reduced FEV1 or DLCO told they may not be fit for the planned operation. The scan separates patients in whom surgery remains safe from those for whom it is not.
Tumour located within destroyed upper-lobe lung. The scan informs whether a combined cancer-and-lung-volume-reduction operation could improve breathing while treating the cancer.
Fit patients undergoing small-tumour segmentectomy where confirming the relative contribution of the segment being removed adds precision to the surgical plan.
Patients having a second operation, or surgery after chemoimmunotherapy. Previous treatment alters regional function in ways that are not visible on spirometry alone.
For the full pathway from diagnosis through to surgery, see Lung Cancer Surgery in 2026 →
If you have been told elsewhere that your breathing tests rule out surgery, an independent review — including regional functional imaging where appropriate — is reasonable. Most patients are seen within 2–3 working days.
Book a Consultation →Or call Jo Mitchelson:
020 7952 2882
If you have been told you are not fit for lung surgery on the basis of spirometry alone, an independent review with regional functional imaging where appropriate is reasonable. Appointments at London Bridge Hospital and The Lister Chelsea within 2–3 working days. Self-referrals welcome.
Jo Mitchelson, PA · 020 7952 2882 · pa@lungsurgeon.co.uk
St Thomas’ Hospital #1 UK · Guy’s Hospital #2 UK · London Bridge Hospital #10 UK · Newsweek World’s Best Hospitals 2026
The three-part fitness framework: cardiac risk, operative risk, post-operative breathing.
Robotic SegmentectomyLung-sparing precision resection for small tumours — the operation the regional map enables.
Robotic Lung SurgeryThe da Vinci platform and Firefly infrared imaging used for intra-operative perfusion mapping.
Emphysema Surgery in 2026EBV and LVRS — the practice in which regional functional imaging is the planning standard.
Lung Cancer Surgery in 2026Stage-by-stage pathway from screening to surgery to systemic therapy.
Specialist Second OpinionIndependent review of imaging, fitness assessment, and treatment plan within 2–3 working days.