Objective: We compared phase-inversion tissue harmonic imaging with fundamental B-mode sonography in the evaluation of focal lesions of the kidney.
Subjects and methods: For our prospective study, 114 patients underwent sonography of the kidneys in both modes, fundamental B-mode sonography and phase-inversion tissue harmonic imaging, in a randomly chosen scanning order. Imaging parameters were standardized. Sonographic diagnoses were made under real-time conditions by the examining radiologist. All sonographic diagnoses were compared with a diagnostic reference modality: contrast-enhanced CT, contrast-enhanced MR imaging, or histopathology. Three radiologists different from the examiners evaluated overall image quality, lesion conspicuity, and fluid-solid differentiation for both modalities using hard-copy images.
Results: In 70 patients, fundamental B-mode sonography as the first technique depicted 73 of 111 lesions 10 mm or larger and enabled 71 lesions to be correctly characterized (sensitivity, 65.8%; accuracy, 64.0%). As the first mode, phase-inversion tissue harmonic imaging depicted 57 of 65 focal lesions and enabled 54 lesions to be accurately classified in 44 patients (sensitivity, 87.7%; accuracy, 83.1%). The differences in sensitivity and accuracy were statistically significant (95% confidence interval). For overall image quality, lesion conspicuity, and fluid-solid differentiation phase-inversion harmonic imaging was superior to fundamental B-mode sonography (p < 0.0001).
Conclusion: Phase-inversion tissue harmonic imaging is superior to fundamental B-mode sonography in the sonography of focal kidney lesions because phase-inversion tissue harmonic imaging has better overall image quality, lesion conspicuity, and fluid-solid differentiation. In six cases, phase-inversion tissue harmonic imaging added crucial diagnostic information that changed patient management.