Kenneth Nichols

Hofstra North Shore-LIJ School of Medicine, New York, New York, United States

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Publications (133)398.94 Total impact

  • Journal of Nuclear Cardiology; 01/2015
  • Kenneth J Nichols · Gene G Tronco · Christopher J Palestro
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    ABSTRACT: The superiority of SPECT/CT over SPECT for (99m)Tc-sestamibi parathyroid imaging often is assumed to be due to improved lesion localization provided by the anatomic component (computed tomography) of the examination. It also is possible that this superiority may be related to the algorithms used for SPECT data reconstruction. The objective of this investigation was to determine the effect of SPECT reconstruction algorithms on the accuracy of MIBI SPECT/CT parathyroid imaging. We retrospectively analyzed preoperative MIBI SPECT/CT parathyroid imaging studies performed on 106 patients. SPECT data were reconstructed by filtered back projection (FBP) and by iterative reconstruction with corrections for collimator resolution recovery and attenuation (IRC). Two experienced readers independently graded lesion detection certainty on a 5-point scale without knowledge of each other's readings, reconstruction methods, other test results or final diagnoses. All patients had surgical confirmation of the final diagnosis, including disease limited to the neck, and location and weight of excised lesion(s). There were 135 parathyroid lesions among the 106 patients. For FBP SPECT/CT and IRC SPECT/CT sensitivity was 76% and 90% (p = 0.003), specificity was 87% and 87% (p = 0.90), and accuracy was 83% and 88% (p = 0.04), respectively. Inter-rater agreement was significantly higher for IRC than for FBP (kappa = 0.76, "good agreement", versus kappa = 0.58, "moderate agreement", p < 0.0001). We conclude that the improved accuracy of MIBI SPECT/CT compared to MIBI SPECT for preoperative parathyroid lesion localization is due in part to the use of IRC for SPECT data reconstruction.
    American Journal of Nuclear Medicine and Molecular Imaging 01/2015; 5(2):195-203. · 3.25 Impact Factor
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    Kenneth J Nichols · Andrew Van Tosh
    Journal of Nuclear Cardiology 07/2014; 21(5). DOI:10.1007/s12350-014-9948-7 · 2.65 Impact Factor
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    ABSTRACT: Changes in left ventricular (LV) ejection fraction (EF) seen in gated Rb data are of interest because the heart is in a genuinely different physiologic state during stress than at rest. A measure that validates internal consistency of LV EF data would be highly desirable. Left ventricular mass calculations are performed simultaneously with EF determinations, requiring similar operator choices, and although LV volumes may change from rest to stress, mass values should be constant. Constancy of LV mass calculations could provide a useful internal check on the consistency of LV EF computations.
    Clinical Nuclear Medicine 05/2014; DOI:10.1097/RLU.0000000000000469 · 2.86 Impact Factor
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    ABSTRACT: PURPOSE Presynaptic dopamine transporter 123I-iouflupane (DaT) SPECT imaging facilitates the differentiation of Parkinsonism from essential tremor (ET). Some groups advocate quantitative analyses of caudate (C) or putamen (P) counts for improved differentiation of these two entities, while others recommend applying normal limits to background-corrected counts. This investigation was undertaken to determine which data analysis approach agrees most strongly with a final diagnosis of Parkinsonism. METHOD AND MATERIALS We performed a retrospective analysis of 123I-FP-CIT SPECT data for 50 pts (age 64±12 years; 28 F; 22 M) who were evaluated for movement disorders. Data were reconstructed by OSEM (12 iterations, 8 subsets) and corrected for attenuation by the Chang method. BASGAN software (Eur J Nucl Med Mol Imaging 2007;34:1240–53) generated ratios of automated caudate (AC) & automated putamen (AP) counts per pixel versus background counts per pixel, and dichotomous abnormal values for caudate (DC) and putamen (DP) by applying recently updated age- and sex-adjusted normal limits (Eur J Nucl Med Mol Imaging 2013;40:565-73). In separate processing sessions, a medical physicist manually drew regions of interest to determine maximum caudate (MC) & maximum putamen (MP) counts, without knowledge of other clinical or quantitative results. The diagnosis of the patient’s official report served as the reference standard. ROC analysis determined optimal discrimination thresholds & kappa statistics evaluated strength of agreement. RESULTS Twenty-seven pts had Parkinsonism & 23 had ET. Highest agreement with final diagnoses was found for MP (κ = 0.72), followed by DC, MC, AC, AP & DP (κ = 0.67, 0.64, 0.64, 0.63 & 0.41, respectively). MP also had highest accuracy (86%), with sensitivity of 78% & specificity of 96%. Pixel averaging and statistical noise of background counts were likely reasons that automated output from BASGAN software underperformed manual determinations of maximal counts. CONCLUSION We conclude that, in the analysis of presynaptic dopamine transporter SPECT scans, a straightforward detection of abnormally suppressed putamen counts is the single quantitative measure that agrees most strongly with a diagnosis of Parkinsonism. CLINICAL RELEVANCE/APPLICATION While quantitation of DaT scans can bolster visual determinations of disease states, use of quantitative measures should be applied judiciously in influencing final diagnoses.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE Left ventricular (LV) asynchrony can be quantified by both gated blood pool (BP) & myocardial perfusion (MP) tomography. A concern regarding MP phase measurements is their reliance on tracking myocardial walls in cases of severely reduced MP, for which counts are low. PET data are acquired in gated list mode & both BP & MP data are available for the same pts. To test validity of MP phase measurements for severely decreased MP we compared MP to BP phase measurements, which are not affected by decreased MP. METHOD AND MATERIALS Data were analyzed retrospectively for 67 pts (42 males; 23 females; 71±12 yrs) with suspected heart disease evaluated by 82Rb PET/CT. Data were collected in gated list mode & rebinned into BP tomograms of tracer imaged during the first pass transit through the heart chambers, & separately into MP tomograms of tracer imaged during equilibrium. For BP PET data LV contraction phases were computed for each of 17 LV segments. Excluding the 3 most basal-septal segments to ensure LV cavity sampling the bandwidth (BW) of contraction phases were computed, defined as % of the R-R interval accounting for 95% of LV regional contractions. MP tomograms were analyzed by commercial algorithms, which computed summed rest scores (SRS) indicating severity of MP defects, & MP phase BW derived from phases of maximum count brightness corresponding to regional end-systole at each voxel at locations identified by algorithms as corresponding to the myocardial wall. RESULTS 37 pts had negligible defects (SRS ≤ 4) with BP phase BW = 16±8%, lower than the 30 pts with significant MP defects (SRS > 4) (33±22%, p = 0.0001). BP & MP phase BW were similar for all pts (24±% versus 26±16%, p = 0.49), pts with SRS ≤ 4 (16±8% versus 19±9%, p = 0.15), & pts with SRS > 4 (33±23% versus 36±19%, p = 0.50). BP & MP phase BW correlated significantly & similarly with SRS (r = 0.59, p < 0.0001 & r = 0.61, p < 0.0001), consistent with greater amounts of asynchrony being related to more severe myocardial damage. Differences between BP & MP phase BW had no correlation to SRS (r = 0.04, p = 0.75). Thus, severe MP defects had no deleterious effect on MP phase quantitation. CONCLUSION Detection of LV asynchrony by phase measurements derived from gated 82Rb PET/CT tomograms are robust & reliable, regardless of severity of MP defects. CLINICAL RELEVANCE/APPLICATION It is justifiable to include scintigraphic asynchrony measurements in forming clinical impressions for pts exhibiting severe MP defects.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE Technologists in our high volume outpatient PET/CT practice (approximately 3,500 studies/year) consistently received high radiation badge readings (>0.5 mSv/month). We undertook this investigation as part of a quality improvement project aimed at understanding and reducing technologist radiation exposure. To address these issues we (1) analyzed technologist radiation badge readings as a function of work hours; (2) determined relative radiation exposure during various segments of PET/CT workflow; (3) implemented and assessed the effectiveness of a radiopharmaceutical auto-injector for reducing technologist radiation exposure. METHODS Monthly body and ring radiation badge readings and work hours were analyzed for 6 technologists performing 2-3 manual injections of 444-555 MBq 18F-FDG/shift. For 4 technologists 12 months of data were available for analysis. For the fifth and sixth technologists, nine months and five months, respectively, of data were available for analysis. Annual mean radiation dose equivalent values per hour (mSv/hr) were computed for each technologist for the manual injection technique. PET/CT workflow was divided into 3 segments: (1) preparation/injection of 18F-FDG; (2) positioning patient on scanner; and (3) removing patient from scanner. For both manual and auto-injector techniques the technologists used pocket dosimeters to determine their radiation exposure from 10 patients during each of the 3 segments of PET/CT workflow. Total radiation exposure and per cent of total radiation exposure from each workflow segment, for both injection techniques, were compared. RESULTS Using the manual injection technique, mean body dose was 0.0037±0.0012 mSv/hr (institutional ALARA limit 0.0025 mSv/hr) and mean hand dose was 0.0129±0.0074 mSv/hr (institutional ALARA limit 0.025 mSv/hr). By two-way ANOVA, radiation doses per MBq of injected activity were similar among technologists for segment 1 (p=0.86) and for the entire procedure (p=0.24), but were significantly higher for the manual injection technique than for the auto injector (p=0.003). For the manual injection technique, radiation doses per MBq of injected activity were significantly higher for segment 1 than for segments 2 (0.0084±0.0005 versus 0.0048± 0.0022, p=0.002), and segment 3 (0.0084±0.0005 versus 0.0028±0.0012, p<0.0001), and similar for segments 2 & 3 (p=0.08). For the autoinjector technique, radiation doses to technologists per MBq of injected activity were similar for segments 1 and 2 (0.0038±0.0014 versus 0.0047±0.0013, p=0.29), but significantly higher for segment 2 than 3 (0.0023±0.0012, p=0.008). Based on analysis of technologist radiation badge readings and work hours, assuming current staffing and patient volumes, technologists working full time (150 hr/month), could be expected to receive an average of 0.56 mSv/month to the body and 1.94 mSv/month to the hand, using the manual injection technique. Although well below occupational dose limits, this mean body dose exceeds institutional ALARA limits. Analysis of relative radiation exposure during each of the 3 PET/CT workflow segments showed that process improvement in the injection phase would be most beneficial for reducing technologist exposure. Re-analysis of relative radiation exposure during the 3 PET/CT workflow segments using the auto-injector technique demonstrated a 55% decrease in technologist radiation exposure during the injection phase and a 40% overall decrease in radiation exposure. CONCLUSION The introduction of a radiopharmaceutical auto-injector, as our data indicate, has the potential to significantly reduce radiation exposure to technologists administering 18F-FDG.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: Gated rubidium-82 ((82)Rb) positron emission tomography (PET) imaging studies are acquired both at rest and during pharmacologic stress. Stress-induced ischemic left ventricular dysfunction (LVD) can produce a significant decrease in left ventricular ejection fraction (LVEF) from rest to stress. We determined the prevalence on PET of stress LVD with reduced ejection fraction (EF) and its association with absolute global and regional coronary flow reserve (CFR), and with relative perfusion defect summed difference score (SDS). We studied 205 patients with known or suspected coronary disease (120 M, 75 F, age 69 ± 13 years) who had clinically indicated rest/regadenoson stress (82)Rb PET/CT studies. Data were acquired in dynamic gated list mode. Global and 17-segment regional CFR values were computed from first-pass flow data using a 2-compartment model and factor analysis applied to auto-generated time-activity curves. Rest and stress LVEF and SDS were quantified from gated equilibrium myocardial perfusion tomograms using Emory Cardiac Toolbox software. LVD was defined as a change in LVEF of ≤-5% from rest to stress. A subgroup of 109 patients also had coronary angiography. Stress LVD developed in 32 patients (16%), with mean EF change of -10 ± 5%, vs +6 ± 7% for patients without LVD (P < .0001). EF was similar at rest in patients with and without stress LVD (57 ± 18% vs 56 ± 16%, P = .63), but lower during stress for patients with LVD (47 ± 20% vs 61 ± 16%, P = .0001). CFR was significantly lower in patients with LVD (1.61 ± 0.67 vs 2.21 ± 1.03, Wilcoxon P = .002), and correlated significantly with change in EF (r = 0.35, P < .0001), but not with SDS (r = -0.13, P = .07). The single variable most strongly associated with high risk of CAD (i.e., left main stenosis ≥50%, LAD % stenosis ≥70%, and/or 3-vessel disease) was stress EF (χ(2) = 17.3, P < .0001). There was a higher prevalence of patients with territorial CFR values ≤1.0, consistent with coronary steal, in the LVD group than in the non-LVD group (39% vs 12%, P = .001). LVD developed in 16% of patients undergoing (82)Rb PET myocardial perfusion imaging, and was associated with multivessel coronary artery disease. There was a significant relationship between LVD and coronary blood flow during stress, with LVD corresponding to a low CFR. Territorial CFR ≤1.0 was more common in patients with LVD than those without, suggesting that coronary steal is an important pathophysiologic mechanism contributing to pharmacologic stress-induced LVD.
    Journal of Nuclear Cardiology 10/2013; 20(6). DOI:10.1007/s12350-013-9784-1 · 2.65 Impact Factor
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    Kenneth J Nichols · Denny D Watson
    Journal of Nuclear Cardiology 03/2013; 20(3). DOI:10.1007/s12350-013-9698-y · 2.65 Impact Factor
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    ABSTRACT: CONCLUSION Iterative reconstruction significantly improved perceived image quality and agreement between the resident and senior Nuclear Medicine physician, compared to conventional processing recommended by the manufacturer. BACKGROUND While the manufacturer & some publications recommend using filtered backprojection (F) to process DaT SPECT scans to distinguish Parkinson’s disease (PD) from essential tremor (ET), others recommend iterative reconstruction (I). This investigation was undertaken to determine the influence of processing choices on DaT SPECT scan interpretation. EVALUATION Data were examined retrospectively for 41 pts (age 66±11 years; 23 F; 18M) evaluated for movement disorders by 123I-FP-CIT SPECT as per the manufacturer (F processing; Butterworth filter cutoff=0.5 & order=5) . I was performed with resolution recovery by OSEM (2 iterations & 16 subsets). Right & left caudate & putamen maximum counts & mean background counts were tabulated. Images were read independently by an experienced Nuclear Medicine physician (R1) and a senior Nuclear Medicine resident (R2), blinded to each other’s readings and to processing methods. Readers graded image quality on a scale of 0-4 (“poor”-“excellent”), likelihood of PD from 0-4 (“definitely not PD”-“definitely PD”), and dichotomously scored uptake asymmetry & bilateral uptake reduction. DISCUSSION Image quality was scored significantly higher for I than F by both readers (2.3±0.7 versus 1.7±0.9, Wilcoxon p=0.002). Image quality difference was more pronounced for abnormal studies (1.9±0.6 versus 1.2±0.7, Wilcoxon p=0.002) than normal studies (2.9±0.4 versus 2.3±0.7, Wilcoxon p=0.07), consistent with caudate counts being significantly lower for abnormal than normal studies (276±133 versus 437±158, p=0.001). Inter-rater agreement was significantly higher for I than F-processed scans in discriminating between normal and abnormal studies (κ = 0.77 versus 0.40, p=0.01), and for perceptions of asymmetry in caudate and putamen uptake (κ = 0.85 versus 0.34, p=0.0001), but was similar for perceived bilateral uptake reduction (κ = 0.51 versus 0.52, p=0.95). By logistic regression, disagreement between readers was related to processing techniques (p = 0.03), but not to overall acquired counts (p = 0.11).
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE: Standardized scintigraphic gastric emptying (GE) protocols to detect gastroparesis (GP) require collecting data for 4 h. This investigation was undertaken to compare seven methods to reduce the duration of the test. MATERIALS AND METHODS: This was a retrospective study of GE data collected using a standardized protocol at 0, 1, 2, 3, and 4 h for 602 patients being evaluated for GP. The reference standard was GP defined conventionally as percentage of gastric retention (GR) at 4 h (p4) of greater than 10%. For data up to 2 h the results were derived as follows: (a) confirming as being positive for GP if GR at 2 h was greater than 65%, negative for GP if GR at 2 h was less than 45%, and indeterminate otherwise; (b) by linear extrapolation; and (c) by monoexponential extrapolation. For data beyond 2 h, further evaluations were made and results were derived as follows: (a) confirming as being positive for GP if GR at 2.5 h was greater than 40%; (b) ascertainment of GR at 3 h; (c) by biphasic fit; and (d) by observation of maximum GR for normal patients at time points earlier than 4 h. RESULTS: Thirty percent of all patients had GP. Eighty percent were determinate by Method 1; for these patients sensitivity to detect GP was similar (P=0.11) for Methods 1-3 (69-79%). For data beyond 2 h, sensitivity of the seven methods ranged from 64 to 92%, and the sensitivity of every method was significantly lower than that of the reference standard (P<0.001). CONCLUSION: Considering that sensitivity to detect GP was significantly reduced for data collection limited to 3 h or less, it is not advisable to truncate GE studies earlier than 4 h.
    Nuclear Medicine Communications 11/2012; DOI:10.1097/MNM.0b013e32835bd5da · 1.37 Impact Factor
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    ABSTRACT: PURPOSE It is important to distinguish Parkinson’s disease (PD) from essential tremor (ET), as prognoses and treatments for these conditions are quite different. However, visual assessment of 123I-FP-CIT (DaT) SPECT can be challenging due to depressed radiotracer uptake in pts with PD. This study was designed to determine whether attenuation correction and image quantitation can improve diagnostic accuracy of DaT scans. METHOD AND MATERIALS In order to design realistic simulations with a range of mean counts ±1 standard deviations, caudate (C), putamen (P) and background (B) counts were first tabulated retrospectively from clinical DaT scans for 30 pts. Based on these data, 21 phantoms were acquired simulating 9 ET cases, 6 mild PD cases with unilaterally decreased left or right counts in P & C, and 6 severe PD cases with bilaterally reduced counts in both left & right P & C. Phantoms consisted of two 5-mL syringes with 0.9 MBq of 123I in saline for C’s contiguous to two 5-mL syringes with 0.6 MBq of 123I for P’s submerged in a 2,300 mL water phantom with 38 MBq 123I for B. Data were reconstructed by conventional filtered backprojection (F) recommended by the radiotracer manufacturer, by resolution-recovery-corrected iterative reconstruction (I), and by I with attenuation correction (IAC). All 63 images were read independently by two Nuclear Medicine physicians, blinded to each other’s readings and to processing methods, who graded certainty of PD from 0-4 (“definitely not PD”-“definitely PD”). Ratios of counts among P, C & B derived from processed data were compared to true values. RESULTS C:B ratio for ET simulations was significantly higher for IAC than F (3.1±0.6 versus 2.7±0.6, Wilcoxon p=0.004), but still lower than the true value of 6.8 due to partial volume effects. Nonetheless, the quantified IAC P:B ratio was significantly more accurate than combined readers’ scores of F, I and IAC for discriminating PD from ET simulations (98% versus 84%, 88% & 89% respectively; p=0.002). CONCLUSION Despite partial volume effects that compromised exact count recovery, iterative reconstruction with attenuation correction nonetheless provided measurements closest to true values and produced quantitative measures that were more accurate than visual assessment of 123I-FP-CIT SPECT scans in diagnosing simulated cases of Parkinson’s disease. CLINICAL RELEVANCE/APPLICATION Our results suggest that quantified count ratios provide valuable information in assessing DaT scans.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    Journal of the American College of Cardiology 03/2012; 59(13). DOI:10.1016/S0735-1097(12)61120-6 · 15.34 Impact Factor
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    Journal of the American College of Cardiology 03/2012; 59(13). DOI:10.1016/S0735-1097(12)61180-2 · 15.34 Impact Factor
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    ABSTRACT: While speckle tracking echocardiography (2DSTE) can be used to study longitudinal, circumferential, and radial function, real time 3D echocardiography (3DE) generates dynamic time-volume curves, offering a wide array of new parameters for characterizing mechanical and volumetric properties of the left ventricle (LV). Our aim was to investigate the merit of these new techniques to separate normal from abnormal echocardiograms as well as to identify subclinical disease in reportedly normal subjects. Eighty-one patients (mean age 61 ± 16 years) underwent standard 2D echocardiography (2DE) enhanced by 2DSTE and 3DE. The data included LV volumes and ejection fraction (EF), velocities, strain/strain rate, and peak ejection/filling rates. The patients were divided into Group 1: normal (n = 42) and Group 2: abnormal (n = 39) on the basis of an expert interpretation of the resting 2DE. Global longitudinal strain (%) was 17 ± 4 in Group1 and 14 ± 4 in Group2 (P < 0.002). Strain rates (SR, 1/sec) at peak systole (1.1 ± 0.2 vs 0.9 ± 0.3, P < 0.001) and early diastole (1.3 ± 0.3 vs 0.9 ± 0.3, P < 0.001) were also higher in Group1. Three-dimensional peak ejection and filling rates (EDV/sec) were significantly higher in Group1 (-2.5 ± 0.4 vs -2.1 ± 0.7, and 1.8 ± 0.2 vs 1.5 ± 0.5, P < 0.002, P < 0.001, respectively). The best discriminatory power for predicting a normal 2DE was systolic SR with a sensitivity of 82% and a specificity of 54% using a cutoff value of 1.09. Interestingly, 19/41 (46%) of Group1 patients had systolic SR < 1.09, suggesting subclinical disease. 2DSTE and 3DE can discriminate between normal and abnormal echocardiograms and have the potential to detect subclinical LV dysfunction.
    Echocardiography 02/2012; 29(5):588-97. DOI:10.1111/j.1540-8175.2011.01631.x · 1.25 Impact Factor
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    ABSTRACT: For sestamibi (MIBI) studies in patients with primary hyperparathyroidism, some investigations found that the test sensitivity is lower in patients with multigland disease (MGD) than in those with single-gland disease (SGD), whereas other investigations reported that the sensitivity of MIBI imaging is similar in MGD and SGD. The objectives of this investigation, therefore, were to determine (a) whether there are differences in the sensitivity and specificity of MIBI imaging for detecting parathyroid lesions in patients with MGD and in patients with SGD, (b) whether there is a relationship between test sensitivity and the number of glands involved, (c) whether there are differences in weight between parathyroid lesions in MGD and SGD, (d) whether there are differences in lesion locations between MGD and SGD, and (e) whether MIBI sensitivity in MGD is related to the number, weight, or location of the lesions. This was a retrospective investigation of data for 651 patients with biochemically confirmed primary hyperparathyroidism limited to the neck, who underwent preoperative parathyroid lesion localization using a dual tracer ⁹⁹mTc-MIBI/TcO₄⁻ protocol that included early and late planar pinhole ⁹⁹mTc-MIBI, pinhole thyroid imaging, image subtraction, and single photon emission computed tomography. All patients underwent surgery subsequently. Lesion locations were obtained from operative reports; lesion weights were obtained from pathology reports. One experienced nuclear physician, who had no knowledge of the other test results or the final diagnoses, graded studies on a 5-point scale (0=definitely normal to 4=definitely abnormal) while reading all scintigraphic images simultaneously. There were 851 lesions among the 651 patients. One hundred and thirty-one (20%) patients had MGD and 520 (80%) patients had SGD. Among the patients with MGD, 74 had two lesions, 45 had three lesions, and 12 had four lesions. MIBI imaging was significantly less sensitive (61 vs. 97%, P<0.0001) and specific (84 vs. 93%, P<0.0001) for MGD than for SGD. Weights of MGD lesions were significantly lower than those of SGD lesions [median 190 mg (10-14 600 mg) vs. median 500 mg (48-27 000 mg), Wilcoxon P<0.0001]. Lesion weights decreased significantly with increasing lesion number (r=-0.42, P<0.0001). MIBI sensitivity for 249 MGD lesions (65%) was significantly less (P<0.0001) than for 249 weight-matched SGD lesions (94%). For these weight-matched lesions, the test sensitivity decreased progressively with increasing lesion number (r=0.97, P=0.006). The spatial distribution of MGD and SGD lesions was similar (P=0.19), and the sensitivity was not related to lesion location for MGD (P=0.32) or SGD (P=0.11) lesions. MIBI is significantly less sensitive and specific for detecting parathyroid lesions in MGD than in SGD. Decreased sensitivity is not explained by lesion weight or location, and further studies of factors affecting MIBI imaging in MGD are warranted.
    Nuclear Medicine Communications 01/2012; 33(1):43-50. DOI:10.1097/MNM.0b013e32834bfeb1 · 1.37 Impact Factor
  • Kenneth Nichols · Christopher J. Palestro
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    ABSTRACT: PURPOSE It is recommended that magnitude of shunting from liver to lungs be estimated using Tc-99m-MAA imaging prior to administering Y-90 for selective internal radiotherapy (SIRT) for palliation of liver malignancies. This investigation was undertaken to estimate magnitude of errors in shunt calculations due to pt self-attenuation. METHOD AND MATERIALS Imaging data for 33 pts were analyzed to determine ranges of lung, liver and thoracic background counts (CTS) obtained from simultaneously acquired anterior (ANT) & posterior (POST) planar views following injection of Tc-99m-MAA. Estimates of magnitude of pt self-attenuation were obtained from ratios of ANT:POST CTS in lungs and liver separately, as self-attenuation accounts for the majority of positional count discrepancies, given matched Anger detectors equipped with similar parallel hole collimators. A series of 14 phantom simulations subsequently were performed to simulate realistic pt image data, using a cylindrical plastic water bath and saline bags containing various amounts of Tc-99m. Shunt values were simulated from 8%-25%, to span the 10%, 15% & 20% shunt decision thresholds for modifying administration of Y-90. RESULTS Among the 33 pts, conventionally computed shunt values were 6.1±6.0% (range:1.0-25.1%), thoracic background CTS to liver CTS were +34±20% (range:3-79%), and ratios of ANT:POST lung CTS were +5±26% (range:-29% to +122%), while ratios of ANT:POST liver CTS were +15±49% (range:-143% to +144%). Ratios of ANT:POST lung CTS did not correlate with ratios of ANT:POST liver CTS (r=-0.16, p=0.36), indicating significant variations in upper thorax versus abdominal pt self-attenuation patterns. Using these values for phantom simulations, computed shunts overestimated true phantom values by +4±4% (range = -5% to +14%). Attenuation significantly influenced magnitude of errors (ANOVA F-ratio=25.2, p<0.001). Magnitude of shunt errors was significantly greater in simulations with vs. without background (5±4% vs. 2±3%, p=0.0001), and correlated significantly with increasing background (r=0.46, p<0.0001). CONCLUSION These data suggest that pt self-attenuation and background counts influence shunts computed from pre-SIRT imaging, so that the conventional method of estimating shunting may not be accurate. CLINICAL RELEVANCE/APPLICATION Accuracy of lung shunt estimates using conventional methodology may vary with a pt’s body habitus, potentially resulting in inadequate or excessive administration of radiation.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 12/2011
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    ABSTRACT: PURPOSE Asynchrony of left ventricular (LV) contraction is common in pts with congestive heart failure (CHF) and ECG conduction delays, and may be treatable using cardiac resynchronization therapy. However, the relationships between asynchrony, LV function, and bundle branch block ECG conduction abnormalities (BBB) are not well-defined. We compared the level and prevalence of asynchrony assessed by gated blood pool SPECT (GBPS) to varying degrees of cardiac conduction delay and LV dysfunction in pts with CHF. METHOD AND MATERIALS Data were analyzed retrospectively for 91 pts (70 males; age 67±13 yrs) with suspected CHF who had GBPS & resting 12-lead ECG to evaluate LV function. ECGs were interpreted & QRS duration measured by an experienced reader, who classified conduction as normal (NL) or BBB (including LBBB, RBBB, or nonspecific conduction delay NBBB). All pts were in non-paced sinus rhythm. Regional systolic contraction phases were obtained by GBPS for each of 17 LV segments. Calculated parameters included ejection fraction (EF), phase histogram bandwidth (BW) & standard deviation (SD), & Z-score ((σpt-σNL)/σ(σNL)) (Int J Cardiovascular Imaging 2008;24:717-25). RESULTS ECG conduction was NL in 55/91 (60%) pts & BBB in 36/91(40%). 13 pts had LBBB (14%), 13 (14%) had RBBB & 10 (11%) had NBBB. 48% (45/91) of pts had EF≤35% & 52% (46/91) had EF>35%. EF was lower in pts with BBB vs. NL (33±14% vs. 42±15%; p=0.006), but similar for all BBB patterns. Z-score, BW & SD discriminated between pts with BBB from NL pts with ROC area = 72±6%, 71±6% & 72±6%, respectively. Four categories of LV conduction and function were defined: NL & EF>35%, BBB & EF>35%, NL & EF≤35%, and BBB & EF≤35%. Asynchrony parameters differed significantly between categories: Z-score = 0.8±1.5, 2.6±2.7, 6.0±4.7 & 7.7±5.7 (ANOVA F-ratio=17.6, p<0.001), BW = 64±27º, 93±55º, 157±87º & 169±74º (F-ratio = 17.9, p<0.001) & SD = 19±6%, 26±12%, 42±24% & 50±28% (F-ratio = 9.0, p<0.001), respectively. Prevalence of abnormal Z-score>2.0 among these 4 pt categories was 20%, 46%, 74% & 92%, respectively (p<0.0001). CONCLUSION The degree and prevalence of LV asynchrony correlate with reduced LV function and conduction delay, and should be studied using GBPS, as pts with asynchrony may benefit from cardiac resynchronization therapy. CLINICAL RELEVANCE/APPLICATION In the presence of low EF and BBB, pts should undergo GBPS to evaluate for asynchrony to determine whether they would benefit from cardiac resynchronization therapy.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 12/2011
  • Kenneth Nichols · Christopher J. Palestro
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    ABSTRACT: PURPOSE Accurate scintigraphic detection of gastroparesis (GP) requires collecting data for 4 hrs. This investigation was undertaken to determine if the length of the gastric emptying (GE) test could be shortened without compromising accuracy. METHOD AND MATERIALS This was a retrospective study of GE data collected using a standardized protocol at 0, 1, 2, 3 and 4 hrs for 432 pts (111 men & 321 women; mean age 53±19 yrs). GP was defined as >10% gastric retention at 4 hrs (J Nucl Med Technol. 2008;36:44-54). Simultaneous 1-minute anterior and posterior static images were collected with pts upright. Attenuation-corrected conjugate view counts were determined within manually drawn regions over the stomach. Per cent retention values at 1 hr (p1), 2 hrs (p2) & 3 hrs (p3) were compared by ROC analysis to determine optimal thresholds for predicting GP. We also tested recently published (Clin Nucl Med. 2011;36:283-5) criteria (C2t4) that classifies pts as: having GP if GE < 35% at 2 hrs, and normal if GE > 55% at 2hrs; inconclusive if 55%≥GE≥35% at 2 hrs with continued imaging to 4 hrs. RESULTS 97/432 (23%) pts had GP. At 2 hrs, C2t4 criteria had ROC area of 85±3% for the subgroup with GE < 35% or GE > 55%, and were inconclusive in 17% (75/432) of cases, for which GE values at 2 hrs were 46±7%. Among the remaining 357 (83%) cases, C2t4 failed to detect 28% (18/65) of GP cases. Optimal ROC discrimination thresholds were 71%, 43%, and 28% for p1, p2, and p3, respectively. Using these thresholds to dichotomize methods, and including analysis of C2t4 criteria, resulted in sensitivity of 83%, 85%, 88% and 81%, specificity of 69%, 82%, 95% and 98%, and accuracy of 76%, 83%, 91% and 94% for p1, p2, p3 and C2t4, respectively, for all 432 cases. All sensitivity values were significantly lower (p=0.001) than the 4 hr reference standard sensitivity (100%, by definition). Among the 97 cases of GP, using these criteria to truncate studies at 1, 2 & 3 hrs would have resulted in failure to detect GP in 17%, 15%, 12% & 19% of all cases by p1, p2, p3 & C2t4 criteria, respectively. CONCLUSION Truncating gastric emptying studies at 2 hrs can result in failure to detect 15%-19% of gastroparesis cases. CLINICAL RELEVANCE/APPLICATION Gastric emptying studies should be carried out to 4 hrs to maximize test sensitivity.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 12/2011
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    ABSTRACT: PURPOSE Morphine, an extensively used opiate analgesic, has both pharmacological and pathological effects. Morphine is a cationic anion and it may, therefore, affect renal tubular secretion. This study was designed to investigate the effects of morphine on 99mTc-MAG3, which is cleared by tubular secretion. METHOD AND MATERIALS Nine mice (ages: 8-10 wk.; wt.: 20-25g) were divided into 3 groups: Group 1 (n=3) controls, Group 2 (n=3) morphine treated, & Group 3 (n=3) morphine withdrawal. In Groups 2 & 3, a 75 mg morphine pellet was inserted, under anesthesia, into a subcutaneous pocket on the dorsal aspect of the animal’s neck. In Group 3, the morphine pellet was removed 72 hours after implantation. Group 2 animals were imaged 72 hours after morphine pellet implantation. Group 3 animals were imaged 72 hours after removal of the morphine pellet. All animals underwent the same imaging protocol. A gamma camera equipped with a low energy high resolution collimator & maximum magnification (pixel size = 0.59 mm) was used for image acquisition. Mice were injected with 100 µCi 99mTc-MAG3 via the tail vein & imaged in the dorsal position. The acquisition protocol consisted of sixty 1-second images followed by twenty-nine 1-minute images. Regions of interest were drawn around each kidney and time-activity curves were generated. Split renal function & time to peak activity (Tpeak) were determined. RESULTS Split renal function was not significantly different among the three groups. Right: left kidney ratios were 50.3±3.2%:49.7±3.2% (p=0.83), 50.0±1.7%:50.0±1.7% (p=1.00), & 54.7±7.0%:45.3±7.0% (p=0.18) for Groups 1, 2, & 3, respectively. Tpeak for Group 1 was 1.3±0.5 minutes. Tpeak for Group 2 was 24.6±3.0 minutes, which was significantly longer than Group 1, (p<0.0001). Tpeak for Group 3 was 2.0±1.7 minutes, which was not significantly different from Group 1 (p=0.38) but was significantly shorter than Group 2 (p<0.0001). CONCLUSION Morphine inhibits tubular secretion in mice. This effect, at least after short term administration, appears to be reversible. CLINICAL RELEVANCE/APPLICATION The present study demonstrates that use of 99mTc-MAG3 as a tool to evaluate renal tubular cell function could be compromised in patients receiving morphine.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 11/2011

Publication Stats

2k Citations
398.94 Total Impact Points

Institutions

  • 2015
    • Hofstra North Shore-LIJ School of Medicine
      New York, New York, United States
  • 2007–2014
    • North Shore-Long Island Jewish Health System
      • Division of Nuclear Medicine and Molecular Imaging
      New York, New York, United States
  • 2009–2012
    • Saint Francis Hospital
      Tulsa, Oklahoma, United States
  • 2003–2009
    • St. Francis Hospital
      Roslyn, New York, United States
  • 2004
    • Stony Brook University Hospital
      Stony Brook, New York, United States
    • Stony Brook University
      Stony Brook, New York, United States
  • 2002–2004
    • CUNY Graduate Center
      New York, New York, United States
  • 1999–2004
    • Columbia University
      • Division of Cardiology
      New York, New York, United States
    • Emory University
      • Department of Radiology and Imaging Sciences
      Atlanta, Georgia, United States
    • Gracie Square Hospital, New York, NY
      New York, New York, United States
  • 1994–2004
    • Aurora St. Luke's Medical Center
      Milwaukee, Wisconsin, United States
  • 1998–1999
    • Saint Luke's Hospital (NY, USA)
      New York City, New York, United States
  • 1993–1999
    • St. Luke's Hospital
      Cedar Rapids, Iowa, United States
  • 1996–1998
    • St. Luke School of Medicine
      New York City, New York, United States