Enhancing Lung Scintigraphy With Single-Photon Emission Computed Tomography

https://doi.org/10.1053/j.semnuclmed.2008.06.002Get rights and content

Although widely used for many years in the assessment of pulmonary embolism, planar ventilation-perfusion (V/Q) scintigraphy has well-recognized limitations. Single-photon emission computed tomography (SPECT) imaging, which can be readily performed in most modern nuclear medicine centers equipped with multihead gamma cameras, overcomes many of these limitations through its ability to generate 3-dimensional imaging data. V/Q SPECT has been shown to have a greater sensitivity and specificity than planar imaging and has a lower nondiagnostic rate. For reporting clinicians who may be reluctant to abandon conventional planar V/Q images, planar-like images can also be readily obtained from V/Q SPECT with the use of postacquisition techniques. The use of SPECT can also facilitate advances in V/Q imaging, including the generation of parametric V:Q ratio images, coregistration with computed tomography, respiratory gating, and more accurate quantification of regional lung function. Although direct comparisons in the literature are limited in number, V/Q SPECT appears to have comparable, or greater, sensitivity than multidetector computed tomography pulmonary angiography and is not associated with contrast-related complications such as allergy and nephropathy. It also involves significantly less radiation dose to breast tissue, an important consideration, particularly in young women. For the V/Q scan to remain relevant in the evaluation of patients with suspected pulmonary embolism, it is essential that image data are obtained so as to maximize their accuracy and diagnostic usefulness. V/Q SPECT can achieve this and, furthermore, may have a role in conditions other than pulmonary embolism, including both clinical and research fields.

Section snippets

How to Optimally Perform V/Q SPECT

SPECT can be used to image both ventilation and perfusion, however, this requires the use of appropriate imaging agents.

How Does V/Q SPECT Compare With Planar Imaging?

The advantages of SPECT over planar lung imaging have been demonstrated repeatedly over many years. In a study performed 25 years ago in which subsegmental and segmental clots were induced in dogs, SPECT was shown to be more sensitive than planar imaging.36 Similar results were described by Bajc and coworkers,37 who compared SPECT and planar imaging using 99mTc-DTPA aerosols and 99mTc-MAA in a porcine model. They induced artificial emboli labeled with 201Tl and demonstrated SPECT to have an

How Does V/Q SPECT Compare With CTPA?

Multidetector CTPA has evolved to the point in which it is frequently used as an initial investigation of patients with potential PE. Recent literature suggests that although it is highly specific, its sensitivity is somewhat less than desirable. With the multidetector CT scanners used in the large PIOPED II study, CTPA had a reported sensitivity of 83%, indicating that emboli were not detected in 1 in 6 patients.40 Although the accuracy of CTPA appears to be high in cases in which the scan

How Should V/Q SPECT Results Be Reported?

The optimal way to report V/Q SPECT has yet to be clearly defined, and the supporting literature is sparse. Although the traditional way to report planar scintigraphy has revolved around the use of PIOPED probability categories, the adoption of these criteria to SPECT reporting seems inappropriate. This is particularly so, given that these criteria were derived using planar perfusion imaging and single view 133Xe ventilation, a very different imaging technique to V/Q SPECT.

Reinartz and

Generation of Planar Images From SPECT

For reporting specialists, viewing scintigraphic data in tomographic planes represents a significant change compared with traditional planar reporting. A good ability to relate image data to the underlying segmental lung anatomy is required, something that is helped by having access to an accurate lung atlas. During the transition phase to SPECT imaging, there may be a need for reporting clinicians to view both planar and SPECT data on each patient. Although the acquisition of both data sets

Conclusion

Although it has been used in the diagnosis of PE for many years, it is evident that planar V/Q scintigraphy has some limitations. If the V/Q scan is to remain relevant as an imaging tool, it is important that it be optimized so that the diagnostic information it provides is maximized. V/Q SPECT can be readily performed in most nuclear medicine centers today with no increase in patient imaging time. It has been shown to have superior sensitivity, specificity, reduced interobserver variability,

Acknowledgments

The authors acknowledge the assistance of Elizabeth Bailey who helped to generate the images for this article.

References (74)

  • British Thoracic Society guidelines for the management of suspected acute pulmonary embolism

    Thorax

    (2003)
  • E.M. Baile et al.

    Spiral computed tomography is comparable to angiography for the diagnosis of pulmonary embolism

    Am J Respir Crit Care Med

    (2000)
  • D.R. Anderson et al.

    Computed tomographic pulmonary angiography vs ventilation-perfusion lung scanning in patients with suspected pulmonary embolism: A randomized controlled trial

    JAMA

    (2007)
  • J. Glassroth

    Imaging of pulmonary embolism: too much of a good thing?

    JAMA

    (2007)
  • M.A. Meignan

    Lung ventilation/perfusion SPECT: The right technique for hard times

    J Nucl Med

    (2002)
  • C. Schumichen

    V/Q-scanning/SPECT for the diagnosis of pulmonary embolism

    Respiration

    (2003)
  • N.W. Morrell et al.

    The underestimation of segmental defect size in radionuclide lung scanning

    J Nucl Med

    (1993)
  • Value of the ventilation/perfusion scan in acute pulmonary embolismResults of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED)

    JAMA

    (1990)
  • H.W. Gray et al.

    Lung scan reporting language: What does it mean?

    Nucl Med Commun

    (1993)
  • H.W. Gray et al.

    Lung scan reports: interpretation by clinicians

    Nucl Med Commun

    (1993)
  • P.G. Kember et al.

    Clinicians' interpretation of the indeterminate ventilation-perfusion scan report

    Br J Radiol

    (1997)
  • L.R. Goodman et al.

    Diagnosis of acute pulmonary embolism: Time for a new approach

    Radiology

    (1996)
  • H.R. Scott et al.

    A structured approach to the interpretation and reporting of ventilation/perfusion scans

    Nucl Med Commun

    (1998)
  • H.W. Gray

    The Lung

  • J. Petersson et al.

    Physiological imaging of the lung: Single-photon-emission computed tomography (SPECT)

    J Appl Physiol

    (2007)
  • T. Stavngaard et al.

    Hyperpolarized 3He MRI and 81mKr SPECT in chronic obstructive pulmonary disease

    Eur J Nucl Med Mol Imaging

    (2005)
  • K. Suga et al.

    Clinical utility of co-registered respiratory-gated(99m)Tc-Technegas/MAA SPECT-CT images in the assessment of regional lung functional impairment in patients with lung cancer

    Eur J Nucl Med Mol Imaging

    (2004)
  • M. Bajc et al.

    Diagnostic evaluation of planar and tomographic ventilation/perfusion lung images in patients with suspected pulmonary emboli

    Clin Physiol Funct Imaging

    (2004)
  • A.B. Crawford et al.

    Intrapulmonary distribution of 99mtechnetium labelled ultrafine carbon aerosol (Technegas) in severe airflow obstruction

    Eur Respir J

    (1990)
  • T.C. Amis et al.

    Distribution of inhaled 99mtechnetium labelled ultrafine carbon particle aerosol (Technegas) in human lungs

    Eur Respir J

    (1990)
  • W.M. Burch et al.

    Technegas: particle size and distribution

    Eur J Nucl Med

    (1994)
  • M. Lemb et al.

    Technegas: A study of particle structure, size and distribution

    Eur J Nucl Med

    (1993)
  • P. Peltier et al.

    Comparison of technetium-99m aerosol and krypton-81m in ventilation studies for the diagnosis of pulmonary embolism

    Nucl Med Commun

    (1990)
  • P. Reinartz et al.

    Tomographic imaging in the diagnosis of pulmonary embolism: A comparison between V/Q lung scintigraphy in SPECT technique and multislice spiral CT

    J Nucl Med

    (2004)
  • M. Leblanc et al.

    Prospective evaluation of the negative predictive value of V/Q SPECT using 99mTc-Technegas

    Nucl Med Commun

    (2007)
  • A. Sanchez-Crespo et al.

    A novel quantitative dual-isotope method for simultaneous ventilation and perfusion lung SPET

    Eur J Nucl Med Mol Imaging

    (2002)
  • H.M. Hudson et al.

    Accelerated image reconstruction using ordered subsets of projection data

    IEEE Trans Med Imaging MI

    (1994)
  • Cited by (62)

    • <sup>68</sup>Ga PET Ventilation and Perfusion Lung Imaging—Current Status and Future Challenges

      2016, Seminars in Nuclear Medicine
      Citation Excerpt :

      With the latest developments in integrated multimodality hybrid SPECT/CT cameras, it is now possible to acquire V/Q SPECT scans along with a low-dose CT scan to provide a comprehensive assessment of the pulmonary function and morphology in the patient suspected of PE. Numerous articles have demonstrated the high sensitivity and specificity for the detection of pulmonary emboli using SPECT and SPECT/CT.3-7 Also, the radiation dose from the V/Q scan is acceptably low, making it often the diagnostic imaging test of choice for many patients, in particularly young women and in pregnancy because of the high breast dose from CT pulmonary angiography (CTPA) as well as the reduced accuracy of CTPA in pregnancy.8-12 SPECT V/Q imaging has a role in both clinical medicine and research.

    View all citing articles on Scopus
    View full text