Accuracy of hepatobiliary scintigraphy and added value of SPECT/CT versus planar imaging for diagnosing biliary...

Hepatobiliary scintigraphy (HBS) is an important tool in diagnosing biliary atresia in infants. There is limited evidence on the use of single photon emission computed tomography/computed tomography (SPECT/CT) as an additional imaging method to planar imaging. We evaluated the value of SPECT/CT in unclear cases of planar HBS.

Consecutive patients with suspected biliary atresia who underwent guideline-compliant HBS from January 2010 until March 2020 were reviewed, and cases with SPECT/CT were identified. Each step within the imaging procedure (dynamic, static [early and late], and SPECT/CT) was blindly reread in consensus by two observers and categorized based on a 5-point scale: 0, definitely no bowel excretion (i.e., atresia confirmed); 1, probably positive; 2,equivocal; 3, probably negative; and 4, definite negative (i.e., atresia not confirmed). In this analysis, categories were dichotomized as negative for biliary atresia (scores 3-4) or positive (scores 0-2, including equivocal scans). Available follow-up information constituted the standard of truth (SoT).

Twenty-three infants had HBS, among which ten (4 boys and 6 girls; mean age 36 days; range 8-108) underwent SPECT/CT. Single photon emission computed tomography SPECT/CT was performed as early examination (<8h) in 3 subjects and late (8 to 24 h) in 7 infants. Reread SPECT/CT was categorized as positive for atresia in three infants and negative in seven infants. The SoT showed biliary atresia in one of ten patients. Single photon emission computed tomography/CT was true positive in one case, false positive in two, and true negative in seven. No false negative cases were noted. The diagnostic performance of SPECT/CT showed a sensitivity of 100%, specificity of 78%, positive predictive value (PPV) of 33%, negative predictive value (NPV) of 100%, and accuracy of 90%. For comparison, the diagnostic performance of planar HBS showed a sensitivity of 100%, specificity of 67%, PPV of 25%, NPV of 100%, and accuracy of 70%. In summary, the addition of SPECT/CT to planar HBS improved specificity andaccuracyand marginally improved PPV. Single photon emission computed tomography/CT provided more confidence in the final conclusion in 8/10 patients. In the remaining two cases, SPECT/CT did not improve the level of confidence (one remained equivocal, and one changed from probably no excretion to equivocal).

These preliminary data demonstrated increased accuracy of add-on SPECT to planar HBS predominantly due to improved specificity. This finding is consistent with the existing but limited literature and supports the recommendation of routine use of SPECT/CT or SPECT.