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V/Q Scan📍 Lungs (pulmonary vasculature)Updated on 2026-01-20Radiology reviewed

Pulmonary Hypertension VQ Scan

Understand Pulmonary Hypertension VQ Scan in Lungs (pulmonary vasculature) V/Q Scan imaging, what it means, and next steps.

30-Second Overview

Definition

Patchy, non-segmental perfusion defects that don't match ventilation patterns. Chronic PE may show 'mosaic perfusion' with areas of both increased and decreased uptake. May see normal perfusion with enlarged central arteries.

Clinical Significance

VQ scan helps distinguish chronic thromboembolic pulmonary hypertension (CTEPH) from other causes. Can identify surgically accessible chronic thrombi for pulmonary thromboendarterectomy.

Benign Rate

benignRate

Follow-up

followUp

Imaging Appearance

V/Q Scan Finding

Patchy, non-segmental perfusion defects that don't match ventilation patterns. Chronic PE may show 'mosaic perfusion' with areas of both increased and decreased uptake. May see normal perfusion with enlarged central arteries.

Clinical Significance

VQ scan helps distinguish chronic thromboembolic pulmonary hypertension (CTEPH) from other causes. Can identify surgically accessible chronic thrombi for pulmonary thromboendarterectomy.

Understanding Pulmonary Hypertension VQ Scan

Pulmonary hypertension (PH) is a condition characterized by elevated blood pressure in the pulmonary arteries, which can lead to right heart failure if untreated. VQ scanning plays a crucial role in evaluating PH, particularly in distinguishing chronic thromboembolic pulmonary hypertension (CTEPH)—a potentially curable form of PH—from other causes.

PH is classified into five groups based on cause:

  • Group 1: Pulmonary arterial hypertension (PAH)
  • Group 2: PH due to left heart disease
  • Group 3: PH due to lung disease
  • Group 4: CTEPH (chronic blood clots)
  • Group 5: PH with unclear multifactorial mechanisms

VQ scan is primarily valuable for identifying Group 4 CTEPH, which is potentially surgically curable through pulmonary thromboendarterectomy (PTE).

UrgentCTEPH affects approximately 5-60 people per million, but may be underdiagnosed. Up to 4% of acute PE survivors develop CTEPH.

Patchy, non-segmental perfusion defects or mosaic perfusion pattern suggests chronic thromboembolic pulmonary hypertension, a potentially surgically treatable condition

Why VQ Scan Is Important for PH

VQ scan helps in several ways:

  • Distinguish CTEPH from other PH: CTEPH may be curable with surgery
  • Assess surgical candidacy: Determines which patients may benefit from PTE
  • Monitor treatment response: Evaluate effectiveness of medical or surgical therapy
  • Identify clot distribution: Maps extent of chronic thromboembolic disease
Sensitivity
80-90% for CTEPH

Accuracy highest when combined with CT pulmonary angiography

Specificity
85-92%

Correctly rules out healthy patients

Prevalence
CTEPH accounts for 0.5% of all PH cases but is crucial to identify

Annual new cases

Imaging Patterns in PH

CTEPH Patterns

Chronic thromboembolic PH typically shows:

  • Multiple peripheral perfusion defects
  • Mosaic perfusion pattern (patchy uptake)
  • Non-segmental defects not following anatomical boundaries
  • May show organized thrombi on corresponding CT
  • Often asymmetric between lungs

PAH Patterns

Pulmonary arterial hypertension typically shows:

  • Normal or mildly abnormal perfusion
  • Central arteries may appear enlarged
  • No large mismatched defects
  • May show gradual peripheral pruning of vessels

Other PH Causes

Left heart disease (Group 2):

  • May show redistribution of perfusion to upper lobes
  • Perfusion may appear normal or show mild abnormalities

Lung disease (Group 3):

  • Matched ventilation-perfusion defects
  • Correlates with areas of emphysema or fibrosis

Clinical Scenario

Patient58-year-old
Presenting withProgressively worsening dyspnea on exertion for 2 years, now experiencing shortness of breath with minimal activity. History of acute pulmonary embolism 5 years ago.
Symptoms gradually worsening over 2 years. Now NYHA Class III functional limitation.
ContextEchocardiogram shows pulmonary hypertension (estimated RVSP 65 mmHg). Need to determine if CTEPH is present.
Imaging Indication:VQ scan to evaluate for chronic thromboembolic pulmonary hypertension and assess potential surgical candidacy

Normal VQ Scan

Uniform symmetrical tracer distribution throughout both lungs. No perfusion defects. Normal ventilation pattern. No areas of mismatch or abnormal uptake.

Chronic Thromboembolic PH

Multiple patchy, non-segmental perfusion defects throughout both lungs, more prominent in right lung. Mosaic perfusion pattern with areas of both decreased and increased uptake. Ventilation relatively preserved with mismatched perfusion defects.

Clinical Applications

Distinguishing PH Causes

VQ scan helps differentiate between:

CTEPH (Group 4):

  • Surgically accessible chronic thrombi
  • Potential cure with pulmonary thromboendarterectomy
  • VQ shows mismatched perfusion defects
  • CT pulmonary angiography required for confirmation

PAH (Group 1):

  • Medical management only
  • VQ often normal or mildly abnormal
  • No surgically correctable lesions

Surgical Candidacy Assessment

For potential PTE surgery:

  • Determine clot accessibility: Central vs. peripheral disease
  • Assess extent: Involvement of segmental and subsegmental arteries
  • Evaluate post-PE lung: Function of lung segments
  • Bilateral assessment: Disease in both lungs

Evidence-Based Outcomes

60-80% success rate

For pulmonary thromboendarterectomy in selected CTEPH patients, with significant improvement in symptoms and hemodynamics. Early identification is critical for optimal outcomes.

Source: European Respiratory Journal

Preparing for Your Scan

  • Recent echocardiogram: Helpful for correlation
  • Chest X-ray or CT: Provides anatomical correlation
  • Medical history: Provide details about PE history, symptoms, treatments

Understanding Your Results

What Happens Next?

CT Pulmonary Angiography

1-2 weeks

Confirmatory imaging to precisely map chronic thrombi and assess surgical accessibility.

Right Heart Catheterization

1-2 weeks

Direct pressure measurement to confirm PH severity and assess response to vasodilators.

Multidisciplinary Review

2-3 weeks

PH team review to determine surgical vs. medical management based on clot distribution and patient factors.

Treatment Planning

3-6 weeks

Surgical PTE if operable disease, or medical therapy with pulmonary vasodilators if non-operable.

Frequently Asked Questions

Can CTEPH be cured?

Yes, CTEPH is potentially curable with pulmonary thromboendarterectomy surgery. Up to 60-80% of operated patients experience significant improvement. This makes identifying CTEPH crucial.

How is CTEPH different from other PH?

CTEPH is caused by chronic blood clots that organize and block pulmonary arteries. Unlike other PH types which are managed medically, CTEPH may be cured surgically by removing the organized thrombi.

Will I need surgery?

Not all CTEPH patients are surgical candidates. Operability depends on clot distribution (accessible vs. inaccessible), comorbidities, and overall health. Some patients are managed medically with pulmonary vasodilators.

References

  1. American Heart Association. AHA Guidelines: Pulmonary Hypertension. 2024.
  2. European Society of Cardiology. ESC Guidelines: Pulmonary Hypertension. 2023.

Medical Disclaimer: This information is educational only. Always discuss findings with your healthcare provider for personalized medical advice.

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