Normative Quantitative Values for Dacryoscintigraphy and the Effect of Lid Massage.

Our objectives were to establish normative quantitative values for dacryoscintigraphy in an older population and to evaluate the effect of lid massage. Methods: We conducted a prospective study of 44 eyes of 22 participants aged between 54-90 y that had no symptoms of epiphora and no clinical tear film instability, lid abnormality, lacrimal system impairment, or patent lacrimal duct on syringing. Dacryoscintigraphy was performed and interpreted by a single nuclear medicine physician. The scan protocol involved instillation of 99mTc-pertechnetate in each eye, with a 45-min scan performed with 1-min frames. Lid massage and a sinus clearing maneuver were then performed, followed by a further 45 min of scanning. Results: The mean age of the 22 participants was 71.9 y. Quantitative analysis by half-clearance time (HCT) demonstrated a median presac HCT of 25.5 ± 15.0 min and a whole-eye HCT of 40.0 ± 19.5 min. There was no association between age or sex and HCT. Qualitatively, 29 of 44 eyes (66%) appeared to have at least 1 region of delayed clearance, with improvement noted in 23 after lid massage (79%). Conclusion: We report the quantitative values for dacryoscintigraphy in an asymptomatic older population who had normal findings on lacrimal examination. A high rate of delay in radiotracer transit on qualitative examination suggesting a low specificity. The false-positive rate was significantly improved with the novel approach of adding lid massage, and the significance of this finding merits further research.

Validation of RAH VQ SPECT/CT lobar quantification program using a modified version of GE Q lung.

OBJECTIVE: The value of ventilation-perfusion (VQ) single photon emission tomography/computed tomography (SPECT/CT) lobar quantification for pre-operative assessment of lobectomy and lung volume reduction is known. Our in-house developed software, RAH ventilation perfusion SPECT/CT quantification (RAHVQSQ) has been shown to be able to identify the target lobe for collapse in bronchoscopic lung volume reduction (BLVR) for advanced emphysema. We have proven inter and intra observer reproducibility but are yet to validate the accuracy of our program. This study aims to validate the accuracy of our quantitative program through comparison with a modified version of GE Q lung which is a commercial program certified for clinical use. SUBJECTS AND METHODS: Ventilation-perfusion SPECT/CT data of 19 subjects from our previous study using RAHVQSQ for BLVR assessment were re-analysed using Q lung by 2 technologists independently and in a blinded fashion to determine lobar differential ventilation, perfusion and volume percentages. The data were from GE Hawkeye 4 and external CT, thus a modified version of Q lung was used. To determine interobserver variation in the 3 parameters between the 3 assessors, intraclass correlation coefficient (ICC) and Bland-Altman limits of agreement (LoA) were generated. RESULTS: Paired comparisons between the 3 assessors had high ICC (range for ventilation: 0.69-0.97; perfusion: 0.69-0.97; volume: 0.63-0.97) and means of LoA differences close to zero (range for ventilation: -0.04 - 0.10; perfusion: 0.00-0.02; volume: -0.12 - 0.09) were noted indicative of good concordance for all parameters. CONCLUSION: Using VQ SPECT/CT data of participants with advanced airway disease, our study has found a close concordance of estimated differential lobar ventilation, perfusion and volume percentages using RAHVQSQ when compared with a duplicated blinded assessment using Q lung. The good concordance supports the validity of our quantitative methodology.

Use of Ventilation-Perfusion Single-Photon Emission Computed Tomography to Select the Target Lobe for Endobronchial Valve Lung Volume Reduction.

BACKGROUND: Quantitative planar ventilation-perfusion (VQ) has a complementary role in target lobe selection for endobronchial valve lung volume reduction (EBV-LVR), especially in homogenous disease. We investigated a novel method of lung lobar quantitation using VQ single-photon emission computed tomography (SPECT) with computed tomography (CT) to generate a parameter called the ventilation-perfusion differential index (VQDI). AIM: The aim of this study was to validate VQDI as a parameter for target lobe selection in EBV-LVR against the gold standard test of quantitative computed tomography (qCT). METHODS: This study was a prospective, multi-centre, single-blinded, observational study of EBV-LVR patients. Baseline and 3-month post intervention VQ SPECT and qCT were performed. The target lobe was chosen using qCT and planar VQ report (CTTL) whilst blinded to VQDI. Post EBV-LVR, our nuclear physician, blinded to CTTL, selected a target lobe using deidentified VQDI (VQDITL). Inter-rater agreement between CTTL and VQDITL was calculated by Kappa statistic. Treatment outcomes were analysed with a linear mixed-effects model. RESULTS: There was a high concordance between CTTL and VQDITL in 16 patients (89%, Kappa statistic = 0.85). Post EBV-LVR, our subjects showed significant changes in FEV1 (mean difference [MD] +150 mL, p < 0.001), target lobe volume reduction (MD -973 mL, p < 0.001), residual volume (MD -800 mL, p < 0.001), and St. George's Respiratory Questionnaire score (MD -11, p = 0.001). Improvements in 6-minute walk distances did not reach statistical significance. CONCLUSION: In this study of treatment responders, EBV-LVR target lobe selection using VQDI concurs with qCT and thus supports its value for this purpose. It complements qCT and may potentially be of synergistic value especially in homogenous emphysema.

Value of myocardial perfusion imaging in renal transplant evaluation.

AIM: Myocardial perfusion imaging (MPI) with SPECT (single photon emission computerized tomography) is commonly used for preoperative renal transplant assessment. We performed an audit to evaluate the prognostic value of MPI in this cohort. METHOD: Between 1999 and 2009, 838 transplants were performed in South Australia. A total of 387 patients had 393 preoperative MPI in three hospitals. Using a statewide electronic clinical information system (OACIS) cardiac events, MPI results (positive: any reversible defect; negative: fixed defects and normal), clinical follow up and comorbidities (diabetes and hypertension) were determined. End-point events were 'soft': admission with angina, percutaneous intervention or bypass; or 'hard': myocardial infarction or cardiac death. The end-point event rates were determined using Kaplan-Meier curves. Multivariate analyses were performed for age (60 years), gender, diabetes and hypertension. For negative MPI the event rates in dipyridamole stress were compared with tachycardic stress. RESULTS: Soft events: There was a statistically significant lower event rate for MPI negative versus positive, 3.9% versus 20.8% (hazard ratio 4.4 confidence interval: 2.1-9.6, P < 0.001) at 5 years of follow up - no effect from age, gender, diabetes and hypertension. Hard events: There was a lower event rate for MPI negative versus positive (also unaffected by age, gender, hypertension and diabetes) but the result was not statistically significant, P = 0.153. For negative MPI the soft and hard event rates were similar for dipyridamole and tachycardic stress. CONCLUSION: MPI is a good modality of prognosticating cardiac events in renal failure patients being considered for transplantation. The value of a negative MPI is similar for dipyridamole and tachycardic stress.

Radionuclide arthrogram with SPECT/CT for the evaluation of mechanical loosening of hip and knee prostheses.

OBJECTIVE: To evaluate the value of SPECT/CT in radionuclide arthrogram (RNA) for the assessment of mechanical loosening of hip and knee prostheses. METHOD: A retrospective audit of 117 RNA SPECT/CTs evaluated by a single reader--40 hips, (1 hemiarthroplasty) and 77 knees (12 unicompartmental). The detection of any radiotracer within the bone/prosthetic interface was deemed positive for loosening. The operative assessment of 29 hip and 44 knee prosthetic joints was known and used as the gold standard. A subsequent blinded reassessment of the planar images was performed and compared with the SPECT/CT results for 26 of the 29 hip and 42 of the 44 knee prostheses. RESULTS: The respective SPECT/CT versus planar results were as follows: hips--acetabular cup: sensitivity: 73 versus 0%; specificity: 71 versus 100%; positive predictive value: 62% versus indeterminate; negative predictive value: 80% versus 72% (p = 0.0044). Hips--femoral component: sensitivity: 78 versus 63%; specificity: 90 versus 94%; positive predictive value: 78 versus 83%; negative predictive value: 90 versus 85% (p = 0.2482). Knees--femoral component: sensitivity: 75 versus 17%; specificity 63 versus 97%; positive predictive value: 43 versus 67%; negative predictive value: 87 versus 74% (p = 0.0001). Knees--tibial component: sensitivity: 86 versus 63%; specificity: 86 versus 76%; positive predictive value: 55 versus 38%; negative predictive value: 97 versus 90% (p = 0.6831). CONCLUSION: For evaluation of mechanical loosening of the hip prosthesis SPECT/CT was significantly better than planar scanning for the acetabular cup, but not for the femoral stem. For evaluation of the knee prosthesis, a significant improvement was noted using SPECT/CT for the femoral component, and although superior results were also noted for the tibial component, statistical significance was not reached. Taking into account the limitations of this retrospective audit, the value of using RNA SPECT/CT appeared to lie in the exclusion of mechanical loosening.