Combined visual and quantitative assessment of somatostatin receptor scintigraphy for staging and restaging of neuroendocrine tumors.

PURPOSE: Somatostatin receptor scintigraphy (SRS) using 111In-DTPA-DPhe1-octreotide (pentetreotide) has become an integral part of neuroendocrine neoplasm management. The lack of precise quantification is a disadvantage of SRS. This study aimed to adapt the standardized uptake value (SUV) to SRS, establish the SUV range for physiological uptake in the liver, kidney, and spleen, and elucidate the utility of combined visual and quantitative SRS assessment for staging and restaging of neuroendocrine tumors (NETs). MATERIALS AND METHODS: This study included 21 patients with NETs who underwent 111In-pentetreotide SRS. The SUV of physiological and pathological uptake was calculated using bone single-photon emission computed tomography (SPECT) quantitative analysis software (GI-BONE). For visual analysis, the primary and metastatic lesions were scored visually on planar and SPECT images using a five-point scale. We assessed the relationships between the SUVs of the liver, kidney, and spleen in the dual phase, and among quantitative indices, visual score, and pathological lesions classification. RESULTS: Sixty-three NEN lesions were evaluated. The mean ± standard deviation maximum SUVs (SUVmax) were liver: 4 h, 2.6 ± 1.0; 24 h, 2.2 ± 1.0; kidney: 4 h, 8.9 ± 1.8; 24 h, 7.0 ± 2.0; and spleen; 4 h, 11.3 ± 4.5; 24 h, 11.5 ± 7.6. Higher SUVmax was significantly associated with higher visual scores on dual-phase SPECT (4 h, p < 0.001; 24 h, p < 0.001) (4 h: scores 3 and 4, p < 0.05; scores 3 and 5: p < 0.01; scores 4 and 5: p < 0.01; 24 h: scores 3 and 4, p = 0.0748; scores 3 and 5: p < 0.01; scores 4 and 5: p < 0.01). CONCLUSION: We adapted the SUV to SRS and established the range of SUV for physiological uptake in the liver, kidney, and spleen. Combined visual and quantitative assessment is useful for imaging individual lesions in greater detail, and may serve as a new tumor marker of SRS for staging and restaging of NETs.

New quantitative indices of cardiac amyloidosis with 99mTc-pyrophosphate scintigraphy.

PURPOSE: Amyloid light chain (AL) and transthyretin (ATTR) are the major subtypes of cardiac amyloidosis (CA). 99mTc-pyrophosphate (PYP) scintigraphy is used to differentiate ATTR from other CA subtypes. We adapted the standardized uptake value (SUV) for 99mTc-PYP and proposed two quantitative indices, amyloid deposition volume (AmyDV) and total amyloid uptake (TAU). This study aimed to evaluate the utility of these quantitative indices in differentiating ATTR from non-ATTRs. MATERIALS AND METHODS: Before the SUV measurement, the Becquerel calibration factor (BCF) of 99mTc was obtained by a phantom experiment. Thirty-two patients who had undergone hybrid SPECT/CT imaging 3 h after injection of 99mTc-PYP (370 MBq) were studied. CT attenuation correction for image reconstruction was applied in all. We calculated SUV, AmyDV, and TAU using a quantitative analysis software program for bone SPECT (GI-BONE) and analyzed AmyDV using two methods: threshold method (set 40%); and constant value method (average SUVmax of ribs). We assessed the diagnostic ability of heart-to-contralateral lung (H/CL) ratio, SUV, AmyDV, and TAU to differentiate ATTR from non-ATTR using receiver operating characteristic (ROC) analysis. RESULTS: Statistically significant differences in all quantitative indices were observed between ATTR and non-ATTR. The area under the curve of each quantitative index for discriminating between ATTR and non-ATTR were as follows: H/CL, 0.997; SUVmax, 0.953; SUVmean (M1), 0.964; SUVmean (M2), 0.969; AmyDV (M1), 0.875; AmyDV (M2), 0.974; and TAU, 0.974. The AmyDV (M2) had higher diagnostic ability than AmyDV (M1). Thus, TAU was calculated as AmyDV (M2) × SUVmean (M2). In the ROC curve, SUV, AmyDV, and TAU had almost the same diagnostic ability as H/CL in distinguishing ATTR from non-ATTRs. CONCLUSIONS: We propose two novel 3D-based quantitative parameters (AmyDV and TAU) that have almost equal ability to discriminate ATTR from non-ATTR.

Effect of different examination conditions on image quality and quantitative value of amyloid positron emission tomography using 18F-flutemetamol.

OBJECTIVE: The recommended start time for 18F-flutemetamol amyloid positron emission tomography (PET) examination is 60-120 min after 18F-flutemetamol injection, while an acquisition time of 10-30 min is generally recommended. We aimed to elucidate the effects of different examination conditions on image quality, diagnostic ability, and quantitative value of amyloid PET using 18F-flutemetamol. METHODS: We acquired data on a Discovery PET/computed tomography 710 scanner using Hoffman brain and pillar phantoms with 20 MBq of 18F for 30 min. The images were reconstructed into 10-, 20-, and 30-min periods. The ordered subset-expectation maximization algorithm was used for image reconstruction, which uses a 2- or 4-mm Gaussian filter and a combination of iteration and subset numbers. The percentage contrast and coefficient of variation (CV; as the image noise) were used as physical evaluation indices for reconstructed images, and images with superior contrast and low image noise were selected for clinical evaluation. The imaging data of 15 symptomatic patients (n = 7 and n = 8 for positive and negative diagnoses of Alzheimer's disease, respectively) were reconstructed under the phantom study conditions. Radiographers visually evaluated and ranked the clinical images based on the overall contrast and image noise, and nuclear medicine specialists diagnosed Alzheimer's disease. We compared the standardized uptake value ratio (SUVR) obtained with different acquisition conditions. RESULTS: The basic study using the phantom revealed high convergence of contrast and image noise in five patterns of acquisition time and filter strengths. Regarding visual evaluation, the use of a 2-mm Gaussian filter caused difficulties in diagnosis because the brain parenchymal accumulation was mottled with high image noise. Differences in image quality and diagnostic ability due to different examination times were not significant. Differences in the SUVR were not significant in patients with a negative Alzheimer's disease diagnosis; in patients with a positive diagnosis, the SUVR showed significant fluctuation depending on the acquisition conditions. CONCLUSION: The differences in image quality and diagnostic performance due to the differences in 10-min acquisition time were not significant; however, of note, SUVR showed significant fluctuation depending on the acquisition conditions in patients diagnosed with Alzheimer's disease.

A new quantitative index in the diagnosis of Parkinson syndrome by dopamine transporter single-photon emission computed tomography.

OBJECTIVE: Dopamine transporter single-photon emission computed tomography (DAT SPECT) has been widely used to diagnose Parkinson syndrome. Using the standardized uptake value (SUV) of DAT SPECT, we propose "functional dopamine transporter volume (f-DTV)" as a new quantitative index to evaluate the three-dimensional volume of functional dopamine transporters and assess its diagnostic ability in differentiating dopaminergic neurodegenerative diseases (dNDD) from non-dNDD. METHODS: Seventy-nine patients were enrolled (42 dNDD, 37 non-dNDD; 38 men; age 24-88 years). We analyzed seven quantitative indices. The specific binding ratio (SBR) was calculated using a program specialized for DAT SPECT (SBR_Bolt). The SUVmax, SUVpeak, and SUVmean were calculated using a quantification program for bone SPECT. SBR_SUV was calculated by dividing striatal SUVmean by the average of background SUVmean. The cutoff value of the active dopamine transporter level was examined using three methods (threshold of 40% of SUVmax, SUV 2, and SUV 3) to calculate the active dopamine transporter volume (ADV). The f-DTV was calculated by multiplying ADV and SUVmean. We assessed the correlations between SBR_Bolt and SBR_SUV, and compared the mean value of each index between the dNDD and non-dNDD groups. The abilities of SBR_Bolt, SBR_SUV, SUVmax, SUVpeak, SUVmean, ADV, and f-DTV in differentiating dNDD from non-dNDD were determined by the area under the receiver operating curve (AUC) generated by the receiver operating characteristics analysis. RESULTS: The SBR_Bolt and SBR_SUV highly correlated with each other (r = 0.71). The cutoff value of the active dopamine transporter level was determined as SUV 3. All seven quantitative indices showed lower values in the dNDD group than in the non-dNDD group, and the difference between the two groups was statistically significant (p < 0.05). Sensitivity, specificity, and AUC of f-DTV were slightly lower than those of SBR_Bolt (71%, 79%, and 0.81, respectively, for f-DTV, and 81%, 84%, 0.88, respectively, for SBR_Bolt). The difference in AUC between f-DTV and SBR_Bolt was not statistically significant. CONCLUSIONS: This study demonstrates the utility of f-DTV as a novel quantitative index for evaluating the three-dimensional volume of functional dopamine transporters, and that f-DTV has almost the same diagnostic ability to differentiate dNDD from non-dNDD using DAT SPECT.

The Utility of a Combination of 99mTc-MIBI Washout Imaging and Cardiac Magnetic Resonance Imaging in the Evaluation of Cardiomyopathy.

Background: In cardiomyopathy, 99mTc-MIBI washout can reflect mitochondrial dysfunction and late gadolinium enhancement (LGE) on cardiac magnetic imaging (MRI) is associated with tissue fibrosis. We sought to determine the relationship between 99mTc-MIBI uptake, 99mTc-MIBI washout, and LGE on MRI in patients with cardiomyopathy. Methods: Twenty-one patients underwent rest myocardial perfusion scintigraphy at 45 minutes (early) and 4 hours (delayed) after intravenous 99mTc-MIBI administration and cardiac MRI. We assessed myocardial perfusion, 99mTc-MIBI washout, and LGE. We divided the left ventricle (LV) wall into 16 segments using a polar map. Then, we classified each segment into 5 groups according to 99mTc-MIBI uptake in early-rest images and washout. Additionally, we created a contingency table based on LGE presence/absence in the groups. Results: We evaluated 336 segments in 21 patients. 99mTc-MIBI uptake was decreased in 168 segments in the early-rest 99mTc-MIBI images. 99mTc-MIBI washout was observed in 108 segments with either normal perfusion or reduced perfusion in the early-rest 99mTc-MIBI images. LGE was positive in 104 segments. A contingency table analysis with Fisher's exact test showed that LGE was observed significantly more frequently in the segments with decreased 99mTc-MIBI uptake (p<0.001). In segments without a decreased 99mTc-MIBI uptake, there was a significant correlation between increased 99mTc-MIBI washout and the presence of LGE (p=0.033). Conclusions: In cardiomyopathy, the mitochondrial dysfunction in the early stage is shown as 99mTc-MIBI washout, and fibrotic changes in the myocardium in advanced stages are shown as LGE on cardiac MRI. The severity of myocardial damage and the clinical stage of cardiomyopathy can be evaluated using multimodal imaging.

The utility of the combination of a SPECT study with [123I]-FP-CIT of dopamine transporters and [123I]-MIBG myocardial scintigraphy in differentiating Parkinson disease from other degenerative parkinsonian syndromes.

OBJECTIVE: Molecular imaging of nigrostriatal dopamine transporters (DAT) and sympathetic cardiac innervation with single-photon emission computed tomography (SPECT) are useful tools for differentiating idiopathic Parkinson disease (PD) from other degenerative parkinsonian syndromes (non-PD). Nevertheless, these modalities are often insufficient for achieving a definite diagnosis. The aims of this study were to evaluate the diagnostic accuracy of the combination of these tools. MATERIALS AND METHODS: The SPECT radiotracers [I]-N-ω-fluoropropyl-2ß-carbomethoxy-3ß-(4-iodophenyl)-nortropane (FP-CIT) and meta-[I]-iodobenzylguanidine (MIBG) were used to research presynaptic dopaminergic projections (DAT SPECT) and myocardial adrenergic innervation (MIBG scintigraphy), respectively. PD patients (n=15; age: 61.5±13.6 years) and non-PD patients (n=19; age: 62.6±14.2 years) who underwent both tests were enrolled in this study. Receiver-operating characteristic analyses were used to set the cutoff values of the specific binding ratio in DAT SPECT and the heart to mediastinum ratio in delayed scan in MIBG scintigraphy for differentiating PD from non-PD. We calculated the sensitivity, specificity, and test accuracy of the individual methods and also the combination of these two modalities. RESULTS: When DAT SPECT and MIBG scintigraphy were used individually, they showed mild accuracy in differentiating PD from non-PD (DAT, 67.6%; MIBG, 67.6%). The combination of the two approaches using cutoff values of less than 3.24 for the specific binding ratio and less than 2.745 for the delayed heart to mediastinum ratio enabled more accurate differentiation between PD and non-PD. The accuracy of these indices in distinguishing PD from non-PD was 79.4%. CONCLUSION: These results suggested that the combination of DAT SPECT and MIBG scintigraphy may improve the diagnostic accuracy in differentiating PD from non-PD.

Operator-bias-free comparison of quantitative perfusion maps acquired with pulsed-continuous arterial spin labeling and single-photon-emission computed tomography.

PURPOSE: We compared the regional cerebral blood flow (rCBF) obtained by pulsed continuous arterial spin labeling (pCASL) and iodine-123-N-isopropyl-p-iodoamphetamine (IMP) single photon emission computed tomography (SPECT) using 3-dimensional stereotactic region-of-interest (ROI) software for automated definition of ROIs in anatomic regions of the brain. METHODS: Thirteen patients with cerebrovascular occlusive disease and three with transient ischemic attacks underwent pCASL and IMP SPECT imaging. We compared rCBF values of each anatomic region and calculated the correlation coefficients between pCASL and IMP SPECT. We also calculated the asymmetry index (AI) using ROIs in contralateral regions of the hemispheres. RESULTS: The rCBF values calculated from pCASL and IMP SPECT were comparable in most segments, but rCBF in the thalamus (P < 0.0001) and hippocampus (P = 0.0006) was significantly higher measured by pCASL than IMP SPECT. The correlation of rCBF between pCASL and IMP SPECT in the affected hemisphere (r = 0.50) tended to be lower than that in the normal hemisphere (r = 0.59), but not significantly different (P = 0.25). Moreover, there was a fixed bias for underestimation of rCBF by pCASL (P = 0.0047) in the affected hemisphere. The calculated AI showed a significant relationship between methods (r = 0.79, P < 0.0001). CONCLUSION: The rCBF obtained by pCASL had positive relationships with IMP SPECT. However, it should be considered that pCASL tends to have a weak relationship with IMP SPECT in some normal regions and regions affected by cerebrovascular occlusive disease.

Comparison of monophasic versus biphasic stimulation in rTMS over premotor cortex: SEP and SPECT studies.

OBJECTIVE: To optimize the clinical uses of repetitive transcranial magnetic stimulation (rTMS), we compared the effects of rTMS on somatosensory-evoked potentials (SEPs) and regional cerebral blood flow (rCBF) using different phases (monophasic vs. biphasic) or frequencies (0.2Hz vs. 0.8Hz) of stimulation. METHODS: In the first experiment, different phases were compared (0.2Hz monophasic vs. 0.2Hz biphasic). Biphasic 1Hz or sham condition served as controls. The second experiment was to explore the effect of frequencies (0.2Hz vs. 0.8Hz) using the monophasic stimulation. Substhreshold TMS was applied 250 times over the left premotor cortex. Single photon emission computed tomography (SPECT) was performed before and after monophasic 0.2Hz or biphasic 1Hz rTMS. RESULTS: Monophasic rTMS of both 0.2 and 0.8Hz significantly increased the ratio of N30 amplitudes as compared with sham rTMS, whereas biphasic stimulation showed no significant effects. SPECT showed increased rCBF in motor cortices after monophasic 0.2Hz rTMS, but not after biphasic 1Hz stimulation. CONCLUSIONS: Monophasic rTMS exerted more profound effects on SEPs and rCBF than biphasic rTMS over the premotor cortex. SIGNIFICANCE: Monophasic rTMS over the premotor cortex could be clinically more useful than biphasic rTMS.