Usefulness of 99mTc-Pertechnetate SPECT-CT in Thyroid Tissue Volumetry: Phantom Studies and a Clinical Case Series.

BACKGROUND: An accurate measurement of the target volume is of primary importance in theragnostics of hyperthyroidism. OBJECTIVE: Our purpose was to evaluate the accuracy of a threshold-based isocontour extraction procedure for thyroid tissue volumetry from SPECT-CT. METHODS: Cylindrical vials with a fixed volume of 99mTcO4 at different activities were inserted into a neck phantom in two different thickness settings. Images were acquired by orienting the phantom in different positions, i.e., 40 planar images and 40 SPECT-CT. The fixed values of the isocontouring threshold for SPECT and SPECT-CT were calculated by means of linear and spline regression models. Mean, Median, Standard Deviation, Standard Error, Mean Absolute Percentage Error and Root Mean-Square Error were computed. Any difference between the planar method, SPECT and SPECT-CT and the effective volume was evaluated by means of ANOVA and posthoc tests. Moreover, planar and SPECT-CT acquisitions were performed in 8 patients with hyperthyroidism, considering relevant percentage differences greater than > 20% from the CT gold standard. RESULTS: Concerning phantom studies, the planar method shows higher values of each parameter than the other two methods. SPECT-CT shows lower variability. However, no significant differences were observed between SPECT and SPECT-CT measurements. In patients, relevant differences were found in 7 out of 9 lesions with the planar method, in 6 lesions with SPECT, but in only one with SPECT-CT. CONCLUSION: Our study confirms the superiority of SPECT in volume measurement if compared with the planar method. A more accurate measurement can be obtained from SPECT-CT.

Usefulness of Hybrid Single-Photon Emission Computed Tomography/ Computed Tomography in a Case of Ectopic Thyroid Tissue in the Thyroglossal Duct Remnant.

Here, we report a case of a 54-year-old woman affected by thyrotoxicosis, with scintigraphic evidence of a diffuse hyperfunctioning goiter and a large ectopic thyroid tissue in the thyroglossal duct remnant. The latter was apparently more active than the two lobes at 99mTc-pertechnetate scintigraphy, mimicking a condition of preexisting increased sensitivity to thyroid-stimulating hormone stimulation. On the other hand, single-photon emission computed tomography/computed tomography has proven to be a very useful tool in demonstrating this activity to be similar to the thyroid lobes and in defining extension and anatomical relationships of the mass.

Evaluation of Left Ventricular Volumes and Ejection Fraction from Gated Myocardial Perfusion SPECT Processed with "Myovation Evolution": Comparison of Three Automated Software Packages using Cardiac Magnetic Resonance as Reference.

BACKGROUND: The development of resolution recovery (RR) algorithms has made it possible to preserve the good quality of cardiac images despite a reduced number of counts during study acquisition. OBJECTIVE: Our purpose was to evaluate the performance of three different software packages in the quantification of left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) from gated perfusion SPECT, applying a resolution recovery (RR) algorithm (GE Myovation Evolution), with respect to cardiac MRI (cMRI) as a gold standard. METHODS: We retrospectively enrolled 21 patients, with suspected or known coronary heart disease. Images at rest were reconstructed by filtered back projection (FBP) and by an iterative protocol with the RR algorithm. EDV, ESV, and LVEF were automatically computed employing Quantitative Gated SPECT (QGS), Myometrix (MX), and Corridor 4DM (4DM). Any difference in EDV, ESV, and LVEF calculation between cMRI and the three packages (with FBP and iterative reconstruction with RR) was tested using Wilcoxon or paired t-test, with the assumption of normality assessed using the Shapiro-Wilk test. Agreement between imaging reconstruction algorithms and between gated-SPECT software packages and cMRI was studied with Pearson's (r) or Spearman's (R) correlation coefficients and Lin's concordance correlation coefficient (LCC). RESULTS: Intra-software evaluation always revealed very strong correlation coefficients (R, r ≥ 0.8) and excellent LCC coefficients (LCC > 0.95), except for the LCC coefficient between MX-FBP and MX-RR in EDV evaluation, nevertheless considered very good (LCC = 0.94). EDV and ESV had significantly lower value when calculated with the RR algorithm with respect to FBP reconstruction in QGS and MX. LVEF estimation did not show significant differences for QGS-FBP, QGS-RR, MX, and 4DM-RR with respect to cMRI. CONCLUSION: All reconstruction methods systematically underestimate EDV and ESV, with higher underestimation applying only the RR. No significant differences were observed between 4DM - RR and 4DM-FBP, for each parameter, when the 4DM package was used.

Intracranial aspergillosis in children successfully treated with antifungal therapy and surgical intervention.

Invasive aspergillosis is an uncommon but often lethal complication in immunocompromised patients. Despite the progress obtained with new antifungal drugs, intracranial aspergillosis often requires a combined medical and surgical approach. Most cases previously reported in immunocompromised children were fatal. We describe 4 immunosuppressed children with intracranial aspergillosis successfully treated with surgery and antifungal long-term therapy.