ABSTRACT
OBJECTIVES: This study aimed to introduce an improved deconvolution technique for Tc-99m-mercaptoacetyltriglycine renograms based on the combination of a sparse Legendre polynomial representation and the Moore-Penrose inversion matrix (LG). This method reduces the effect of noise on the measurement of renal retention function transit time (TT). METHODS: The stability and accuracy of the proposed method were tested using a renal database containing Monte Carlo-simulated studies and real adult patient data. Two clinical parameters, namely, split function (SF) and mean TT (meanTT), obtained with LG were compared with values calculated with the established method that combines matrix deconvolution and a three-point linear smoothing (F121) as recommended by the 2008 International Scientific Committee of Radionuclides in Nephrourology consensus on renal TT measurements. RESULTS: For simulated data, the root mean square error (RMSE) between the theoretical non-noisy renal retention curve (RRC) and the results of the deconvolution methods applied to the noisy RRC were up to two times lower with LG (p<0.001). The RMSE of the reconvoluted renogram and the theoretical one was also lower for LG (p<0.001) and showed better preservation of the original signal. The SF was neither improved nor degraded by the proposed method. For patient data, no statistically significant difference was found between the SF for the LG method compared with the database values, and the meanTT better agreed with the physician's diagnosis than the matrix or clinical software (Hermes) outputs. A visual improvement of the RRC was also observed. CONCLUSION: By combining the sparse Legendre representation of the renogram curves and the Moore-Penrose matrix inverse techniques, we obtained improved noise reduction in the deconvoluted data, leading to better elimination of non-physiological signals -as negative values- and the avoidance of the smear effect of conventional smoothing on the vascular peak, which both influenced the meanTT measurement.
ABSTRACT
UNLABELLED: Scintimammography (SM) can be used as a complementary test to mammography in patients with suspected breast cancers. This study was undertaken to evaluate the impact of SM on the management of patients with a doubtful or discordant triple diagnosis-that is, mammography, ultrasound, and fine-needle aspiration cytology. The clinical question was variable: initial diagnosis of cancer, suspicion of recurrence, doubtful tumor extension, or search for a primary tumor. METHODS: We performed a retrospective study of 118 procedures in 104 patients with a suggestion of breast cancer, either at initial presentation or after treatment (relapse), with an inconclusive triple diagnosis. Planar and tomographic imaging was performed after injection of (99m)Tc-labeled methoxyisobutylisonitrile ((99m)Tc-MIBI). Results were compared with histopathologic analysis (surgery or core biopsy) in 82 cases and with clinical and imaging follow-up in 36 cases. RESULTS: Breast cancer was proven in 69 cases. SM-SPECT had a sensitivity of 88.4% and a specificity of 67%. Eleven cancers were detected by SPECT, although planar images were negative. SM-SPECT was more sensitive in patients scanned at initial presentation (95%) than in those with suspected recurrence (81%). SM-SPECT correctly evaluated multicentricity or bilaterality in 8 of 11 patients and resulted in an increased tumor size in 8 patients. Overall, SM-SPECT modified the patient management in 58 of 118 cases (49%): SM made the diagnosis of cancer in 30 cases with doubtful or discordant triple diagnosis and ruled out malignancy in 28 cases. CONCLUSION: SM-SPECT is a useful complementary tool for the diagnosis and evaluation of disease extent in patients with an inconclusive triple diagnosis including fine-needle aspiration. The procedure altered the patient management in 49% of the population. These results must be confirmed in a prospective trial.
