The effect of CT-based attenuation correction on the automatic perfusion score of myocardial perfusion imaging using a dedicated cardiac solid-state CZT SPECT/CT.

BACKGROUND: Data regarding cardiac cadmium-zinc-telluride (CZT)-specific augmented databases and their impact on CT-based attenuation correction (AC) perfusion scores in myocardial perfusion imaging (MPI) were obtained on a multiple-pinhole CZT SPECT/CT. METHODS AND RESULTS: Summed stress (SSS) and rest scores (SRS) were measured using automated software in three independent patient groups: group 1 (n = 80) underwent MPI on both CZT and conventional sodium iodide (NaI) devices, group 2 (n = 80) with low coronary artery disease likelihood and normal MPI provided reference CZT databases; and group 3 (n = 152) served to compare AC and non-AC (NAC) scores on CZT. Group 1 CZT and NaI scores gave a significant 1:1 linear correlation for CZT scores referenced to the custom database vs NaI scores referenced to the default database, but these were not concordant when CZT scores were referenced to the default database. AC significantly decreased average SSS and SRS in men vs NAC, 4.29 ± 6.30 vs 5.37 ± 7.26 (P < 0.001) and 2.37 ± 4.72 vs 3.13 ± 5.85 (P < 0.001), but not in women, 2.28 ± 3.42 vs 2.28 ± 3.08 (p NS) and 0.46 ± 1.51 vs 0.61 ± 1.86, (p NS), respectively. CONCLUSIONS: Specifically designed databases for solid-state CZT cardiac SPECT provide accurate quantitation of perfusion scores concordant with those previously validated for conventional SPECT. AC and NAC CZT scores differed significantly, especially in men.

Diagnostic performance of the quantification of myocardium at risk from MPI SPECT/CTA 2G fusion for detecting obstructive coronary disease: A multicenter trial.

BACKGROUND: The effective non-invasive identification of coronary artery disease (CAD) and its proper referral for invasive treatment are still unresolved issues. We evaluated our quantification of myocardium at risk (MAR) from our second generation 3D MPI/CTA fusion framework for the detection and localization of obstructive coronary disease. METHODS: Studies from 48 patients who had rest/stress MPI, CTA, and ICA were analyzed from 3 different institutions. From the CTA, a 3D biventricular surface of the myocardium with superimposed coronaries was extracted and fused to the perfusion distribution. Significant lesions were identified from CTA readings and positioned on the fused display. Three estimates of MAR were computed on the 3D LV surface on the basis of the MPI alone (MARp), the CTA alone (MARa), and the fused information (MARf). The extents of areas at risk were used to generate ROC curves using ICA anatomical findings as reference standard. RESULTS: Areas under the ROC curve (AUC) for CAD detection using MARf was 0.88 (CI = 0.75-0.95) and for MARp and MARa were, respectively 0.82 (CI = 0.69-0.92) and 0.75 (CI = 0.60-0.86) using the ≥70% stenosis criterion. AUCs for CAD localization (all vessels) using MARf showed significantly higher performance than either MARa or MARp or both. CONCLUSIONS: Using ICA as the reference standard, MAR as the quantitative parameter, and AUC to measure diagnostic performance, MPI-CTA fusion imaging provided incremental diagnostic information compared to MPI or CTA alone for the diagnosis and localization of CAD.

3D iteratively reconstructed spatial resolution map and sensitivity characterization of a dedicated cardiac SPECT camera.

BACKGROUND: A solid-state cadmium zinc telluride (CZT) SPECT device provides ultrafast myocardial perfusion imaging (MPI) with a spherical field-of-view (FOV). This study aims at determining the spatial resolution and sensitivity throughout this FOV as a guide for patient positioning. METHODS AND RESULTS: For this CZT camera (Discovery 570c, GE Healthcare), the iteratively reconstructed spatial resolution along 3 Cartesian axes was compared (average resolution 6.9 ± 1.0 mm full-width at half-maximum) using a 2 dimensional array of point sources in air which was aligned with a transverse plane shifted throughout the FOV. Sensitivity was plotted in the central transverse slice and axially in locations comparable to the placement of the heart in 266 rest/stress cardiac studies (M 78, age 63 ± 13 years). The average sensitivity was 0.46 ± 0.19 kc/s/MBq with a transverse gradient of 0.039 ± 0.001 kc/s/MBq/cm (8.9% of the sensitivity per cm). Reconstructed relative activity was uniform (uniformity <9%) and count rate was linear (R = 0.999) over 3 orders of magnitude. CONCLUSIONS: The CZT SPECT camera offers good resolution, sensitivity, and uniformity, and provides linearity in count rate. A gradient of >8%/cm in sensitivity justifies the crucial role of patient positioning with the heart closest to the detector.

Improving Well-being With a Mobile Artificial Intelligence-Powered Acceptance Commitment Therapy Tool: Pragmatic Retrospective Study.

BACKGROUND: Research and dissemination of smartphone apps to deliver coaching and psychological driven intervention had seen a great surge in recent years. Notably, Acceptance Commitment Therapy (ACT) protocols were shown to be uniquely effective in treating symptoms for both depression and anxiety when delivered through smartphone apps. The aim of this study is to expand on that work and test the suitability of artificial intelligence-driven interventions delivered directly through popular texting apps. OBJECTIVE: This study evaluated our hypothesis that using Kai.ai will result in improved well-being. METHODS: We performed a pragmatic retrospective analysis of 2909 users who used Kai.ai on one of the top messaging apps (iMessage, WhatsApp, Discord, Telegram, etc). Users' well-being levels were tracked using the World Health Organization-Five Well-Being Index throughout the engagement with service. A 1-tailed paired samples t test was used to assess well-being levels before and after usage, and hierarchical linear modeling was used to examine the change in symptoms over time. RESULTS: The median well-being score at the last measurement was higher (median 52) than that at the start of the intervention (median 40), indicating a significant improvement (W=2682927; P<.001). Furthermore, HLM results showed that the improvement in well-being was linearly related to the number of daily messages a user sent (ß=.029; t81.36=4; P<.001), as well as the interaction between the number of messages and unique number of days (ß=-.0003; t81.36=-2.2; P=.03). CONCLUSIONS: Mobile-based ACT interventions are effective means to improve individuals' well-being. Our findings further demonstrate Kai.ai's great promise in helping individuals improve and maintain high levels of well-being and thus improve their daily lives.

Directions and magnitudes of misregistration of CT attenuation-corrected myocardial perfusion studies: incidence, impact on image quality, and guidance for reregistration.

UNLABELLED: CT-based attenuation-corrected (AC) myocardial perfusion imaging (MPI) studies may show significant artifacts caused by misregistration between SPECT and CT data. The present study aimed at identifying the directions and magnitudes of misregistration with greatest impact on AC myocardial perfusion image quality. METHODS: The incidence, magnitude, and direction of misregistration were assessed in 248 consecutive stress-rest MPI studies in 124 patients. In addition, cardiac SPECT/CT registration was artificially modified in 40 studies, shifting CT data by +/-1, +/-2, and +/-3 pixels along the cephalad/caudal, dorsal/ventral, and left/right axes. Percentage of change in 5-wall AC-MPI polar map scoring was calculated for each region, and the direction of the shift along each axis was analyzed statistically (Student t test, P < 0.05) and compared to determine the region most significantly affected by each shift (Newman-Keuls test, P < 0.05). Changes in the normal and abnormal summed stress score (SSS) due to artificial misregistration were assessed (kappa-statistics, McNemar differences). RESULTS: SPECT/CT misregistration of more than 1 pixel was found in 73% (181/248) of studies and more than 2 pixels in 23% of studies (57/248). A 3-pixel ventral shift most significantly affected polar map scoring (-15.4% +/- 6.1% change in lateral wall; -7.5% +/- 5.5% change in inferior wall). A 3-pixel dorsal shift resulted in a -9.5% +/- 5.3% apical and -8.8% +/- 5.8% septal change. Polar map scoring was least affected by the cephalad/caudal shift (<5% average change in all regions except for the anterior wall; -9.9% +/- 7.4% change for 3-pixel caudal shift). The most significant changes occurred in the lateral and anterior walls when the myocardium on SPECT overlapped lung tissue on CT, encountered in 16% of studies (40/248). Clinically significant changes (in SSS) occurred for the 3-pixel caudal, dorsal, and right shifts. CONCLUSION: A misregistration of significant magnitude occurred in 23% of studies and in the direction of the most severe artifacts in 16% of studies. Severe misregistration along the dorsal/ventral axis most significantly affected AC-MPI. Quality control of SPECT and CT registration and manual realignment should be performed routinely, with the highest priority in AC studies showing an overlay of the myocardium on SPECT with lung tissue on the CT component of AC-MPI.

Physiologic thymic uptake of 18F-FDG in children and young adults: a PET/CT evaluation of incidence, patterns, and relationship to treatment.

UNLABELLED: (18)F-FDG uptake in the thymus, mainly related to hyperplasia after chemotherapy, has been described. Thymic uptake can challenge the accurate assessment of cancer patients by (18)F-FDG imaging. The present study defines the incidence, patterns, and intensity of thymic (18)F-FDG uptake in relationship to age and time after treatment in a large cohort of patients. METHODS: A total of 559 consecutive (18)F-FDG PET/CT studies in 160 patients (86 men, 74 women; age, 3-40 y) performed at baseline, during treatment, at the end of treatment, and during follow-up were retrospectively reviewed. PET/CT studies were assessed for the presence or absence (T+ or T-, respectively), pattern, and intensity (SUVmax) of increased (18)F-FDG uptake in the anterior mediastinum, localized by the CT component to the thymus. The overall incidence of (18)F-FDG avidity in the thymus in relationship to the patient's age and time after treatment administration were statistically evaluated. RESULTS: There were 137 of 559 T+ studies (25%), with equal sex distribution. T+ studies were found in significantly younger patients (20.6 +/- 9.3 y vs. 27.4 +/- 8.4 y, P < 0.001). Most T+ patients (60%) showed an inverted V pattern of thymic uptake, with additional unilateral mediastinal extension in 24% and focal midline uptake in 16% of studies. T+ studies were encountered in 80% of patients younger than 10 y, compared with 8% of patients in the 31- to 40-y age group. There were 17% T+ studies at baseline, 6% during treatment, 8% at the end of treatment, and 27%-40% during follow-up. The average SUVmax of thymic (18)F-FDG uptake was 3.73 +/- 1.22. CONCLUSION: Thymic (18)F-FDG uptake was found in 28% of the present study population, more frequently after treatment. T+ patients were significantly younger. Thymic uptake was found in 73% of untreated patients up to the age of 13 y and in 8% of patients in the fourth decade of life. Knowledge of this age- and treatment-related incidence of physiologic thymic (18)F-FDG avidity can reduce the number of potential pitfalls in reporting PET/CT studies in cancer patients.

Brain mapping of patients with lung cancer and controls: inquiry into tumor-to-brain communication.

UNLABELLED: Recent converging evidence suggests that the brain may receive stimuli and possibly modulate tumor progression via the vagus nerve. The present study aimed to compare brain metabolism in patients with and without lung cancer and to assess if significant differences exist in regions associated with the vagus nerve. METHODS: Eighteen patients with lung malignancy and 19 controls underwent (18)F-FDG PET of the brain. Brain metabolism was compared using statistical parametric mapping. RESULTS: Patients with lung malignancy showed a statistically significantly higher right cerebellar metabolism. CONCLUSION: This finding may be related to the role of the cerebellum in immune regulation, because of its proximity to the nucleus tractus solitarius innervated by the vagus and its connections with the hypothalamus. This higher metabolism in the right cerebellum may reflect an attempt to reinstate homeostasis in functions such as respiration and immunity pertinent to lung malignancy.

Correction for respiration artefacts in myocardial perfusion SPECT is more effective when reconstructions supporting collimator detector response compensation are applied.

PURPOSE: To assess the impact of respiration on myocardial perfusion imaging (MPI) SPECT processed with advanced algorithmic reconstructions. METHODS: SPECT studies obtained from a phantom simulation and 49 respiratory-gated,one-day 99mTc-sestamibi scans were corrected for respiratory-related cardiac movement. Three types of reconstruction algorithms: (a) filtered back projection (FBP), (b) ordered subset expectation maximization in which collimator detector response was incorporated (OSEMCDR), and (c) OSEM-CDR with additional attenuation and scatter corrections (OSEM-CDRACSC) were applied to the corrected and uncorrected sets and analyzed quantitatively and qualitatively. RESULTS: A discrepancy between the corrected and uncorrected bull's eye maps > or = 10% wasfound in 2%, 10%, and 20% of the FBP, OSEM-CDR, and OSEM-CDR-ACSC scans, respectively. In studies with more than 10-mm respiratory motion, the effect of motion was greater in OSEM-CDR and OSEM-CDR-ACSC datasets as compared to FBP processing.Qualitative and quantitative differences between corrected and uncorrected sets were significantly larger in OSEM-CDR and OSEM-CDR-ACSC data than in those of FBP data. CONCLUSIONS: Respiratory-related cardiac motion significantly affects MPI-SPECT reconstructed with advanced high-resolution reconstruction algorithms such as OSEM-CDR and OSEM-CDR-ACSC and thus may justifies the application of respiratory gating.

Dual "motion-frozen heart" combining respiration and contraction compensation in clinical myocardial perfusion SPECT imaging.

OBJECTIVES: This article assesses the effect of a new correction technique ("motion-frozen heart") which compensates for the previously described nonuniform blurring of myocardial perfusion imaging (MPI) due to respiration motion or cardiac contraction. METHODS: Respiratory and ECG-gated one-day (99m)Tc-MIBI MPI studies performed in 48 patients were evaluated. MPI scans were acquired on a gamma camera supporting list-mode functionality synchronized with an external respiratory strap and an ECG device. Respiratory and cardiac-gated bins were generated using the acquired list file. Respiratory-gated bins were corrected for respiratory motion, followed by correction for cardiac contraction motion. In addition, cardiac contraction correction was applied to cardiac-gated bins uncorrected for respiratory motion. Bullseye maps were generated for uncorrected MPI studies, as well as following correction for respiratory motion, cardiac contraction, and both. The mean difference between each of the correction vs the uncorrected bullseye was calculated. Visual assessment of image quality, severity, and extent of the uncorrected perfusion images and following each of the corrections was performed. RESULTS: Average motion due respiration was 7.0 +/- 2.6 mm in the axial plane. The maximal score difference in segmental uptake greater than 10% was found in 2%, 15%, and 25% following respiratory correction, contraction correction, and dual corrections, respectively. Percent of scans classified with an excellent image quality was 13%, 21%, 42%, and 52% for the uncorrected images and following respiratory correction, contraction correction, and dual corrections, respectively. CONCLUSIONS: A technique that compensates for motion of the heart due to respiration and cardiac contraction in MPI-SPECT was evaluated. Compensating for both respiration and cardiac contraction had the greatest effect on perfusion images resulting in significantly improved image quality.

Unusual packing of soft-shelled nanocubes.

Space-filling generally governs hard particle packing and the resulting phases and interparticle orientations. Contrastingly, hard-shaped nanoparticles with grafted soft-ligands pack differently since the energetically interacting soft-shell is amenable to nanoscale sculpturing. While the interplay between the shape and soft-shell can lead to unforeseen packing effects, little is known about the underlying physics. Here, using electron microscopy and small-angle x-ray scattering, we demonstrate that nanoscale cubes with soft, grafted DNA shells exhibit remarkable packing, distinguished by orientational symmetry breaking of cubes relative to the unit cell vectors. This zigzag arrangement occurs in flat body-centered tetragonal and body-centered cubic phases. We ascribe this unique arrangement to the interplay between shape and a spatially anisotropic shell resulting from preferential grafting of ligands to regions of high curvature. These observations reveal the decisive role played by shell-modulated anisotropy in nanoscale packing and suggest a plethora of new spatial organizations for molecularly decorated shaped nanoparticles.

Correction of heart motion due to respiration in clinical myocardial perfusion SPECT scans using respiratory gating.

UNLABELLED: Several studies have described nonuniform blurring of myocardial perfusion imaging (MPI) due to respiration. This article describes a technique for correcting the respiration effect and assesses its effectiveness in clinical studies. METHODS: Simulated phantoms, physical phantoms, and patient scans were used in this study. A heart phantom, which oscillated back and forth, was used to simulate respiration. The motion was measured on a gamma-camera supporting list-mode functionality synchronized with an external respiratory strap or resistor sensor. Eight clinical scans were performed using a 1-d (99m)Tc-sestamibi protocol while recording the respiratory signal. The list-mode capability along with the strap or sensor signals was used to generate respiratory bin projection sets. A segmentation process was used to detect the shift between the respiratory bins. This shift was further projected to the acquired projection images for correction of the respiratory motion. The process was applied to the phantom and patient studies, and the rate of success of the correction was assessed using the conventional bull's eye maps. RESULTS: The algorithm provided a good correction for the phantom studies. The shift after the correction, measured by a fitted ellipsoid, was <1 mm in the axial direction. The average motion due to respiration in the clinical studies was 9.1 mm in the axial direction. The average shift between the respiratory phases was reduced to 0.5 mm after correction. The maximal change in the bull's eye map for the clinical scans after the correction was 6%, with a mean of 3.75%. The postcorrection clinical summed perfusion images were more uniform, consistent, and, for some patients, clinically significant when compared with the images before correction for respiration. CONCLUSION: Myocardial motion generated by respiration during MPI SPECT affects perfusion image quality and accuracy. Motion introduced by respiration can be corrected using the proposed method. The degree of correction depends on the patient respiratory pattern and can be of clinical significance in certain cases.

PET/CT quantitation of the effect of patient-related factors on cardiac 18F-FDG uptake.

UNLABELLED: The effect of multiple patient-related factors on the degree of cardiac 18F-FDG uptake was assessed. METHODS: Five hundred four consecutive patients undergoing routine 18F-FDG PET/CT studies completed a clinical questionnaire. 18F-FDG uptake was measured as the mean standardized uptake value within the heart delineated on the CT component of the study. Univariate and multivariate analyses assessed the influence of 51 clinical factors on cardiac 18F-FDG uptake. RESULTS: On both multivariate and univariate analyses, cardiac 18F-FDG uptake was significantly lower in diabetics and in patients receiving bezafibrate or levothyroxine. Cardiac 18F-FDG uptake was significantly higher in men, patients younger than 30 y old, fasting duration of <5 h, patients with heart failure, and those receiving benzodiazepines. CONCLUSION: Cardiac 18F-FDG uptake was lower in patients receiving bezafibrate and levothyroxine and higher in patients receiving benzodiazepines. If further confirmed by prospectively designed studies, manipulation of these drugs may represent tools for optimized PET/CT imaging.

The reduction of artifacts due to metal hip implants in CT-attenuation corrected PET images from hybrid PET/CT scanners.

CT beam hardening artifacts near metal hip implants may erroneously enhance or diminish radiotracer uptake following CT attenuation correction (AC) of PET images. An artifact reduction algorithm (ARA) was developed to reduce metal artifacts in CT-based AC-PET. The algorithm employed a Bayes classifier to identify beam-hardening artifacts, followed by a partial correction of the attenuation map. ARA was implemented on phantom and patient 18F-FDG studies using a clinical PET/CT scanner. In phantom studies ARA successfully removed two artifacts of erroneously elevated uptake near a stainless steel hip prosthesis which were depicted in the standard CT-AC PET. ARA has also identified two targets absent on the scanner PET images. Target-to-background ratios were 1.5-3 times higher for ARA-PET than scanner images. In a patient study, metal artifacts were of lower intensity in ARA-PET as compared to standard images. Potentially, ARA may improve detectability of small lesions located near metal hip implants.

Preoperative [99mTc]MIBI SPECT/CT Interpretation Criteria for Localization of Parathyroid Adenomas-Correlation with Surgical Findings.

PURPOSE: Minimally invasive surgery for parathyroid adenomas (PTA) requires precise identification and localization of the diseased gland prior to exploration for optimal surgical planning. The Perrier classification allows for accurate, reproducible, and reliable description of PTA location and communication of clinically significant information to surgeons. The current study compares the Perrier localization of PTA on [99mTc]methoxyisobutylisonitrile ([99mTc]MIBI) single-photon emission computed tomography (SPECT)/X-ray computed tomography (CT) with the results of surgery. PROCEDURES: Eighty-eight patients (60 females), age 13-82 years, with primary hyperparathyroidism underwent [99mTc]MIBI SPECT/CT prior to surgery. Eight patients had parathyroid hyperplasia and underwent excision of 3.5 parathyroid glands, including five patients with a negative [99mTc]MIBI study and three patients with multiple foci of uptake, and were excluded from further analysis. Each PTA was localized to Perrier levels A-G. The surgeon located each PTA found on surgery using the same classification. PTA localization on SPECT/CT and at surgery was compared. RESULTS: Eighty patients with surgically confirmed PTA were analyzed. On [99mTc]MIBI SPECT/CT, 63 patients had a single and one patient had two PTAs for a total of 65 PTAs. At surgery, 85 PTAs were resected in 80 patients, including 75 patients with single and 5 with two PTAs. Twenty PTAs found on surgery were not detected on [99mTc]MIBI. The relatively lower weight of these 20 PTAs is probably the main reason for the false-negative results group. The same Perrier localization was determined on SPECT/CT and surgery in 52/65 PTAs (80 %). In the 13 incongruent cases, the PTAs were localized at different locations but on the same side of the thyroid gland. CONCLUSIONS: [99mTc]MIBI SPECT/CT accurately localized a PTA according to the Perrier classification in 80 % of cases. Reporting SPECT/CT results using anatomy-based PTA localization criteria accepted by surgeons can contribute significantly towards better interspecialty communication and will improve performance of minimally invasive surgical removal of PTAs.

Changing patterns of abnormal vascular wall F-18 fluorodeoxyglucose uptake on follow-up PET/CT studies.

BACKGROUND: Fluorine 18 fluorodeoxyglucose (FDG) uptake may be increased in atherosclerotic plaques in asymptomatic patients. Repeat positron emission tomography (PET)/computed tomography (CT) studies were assessed for changes in patterns of FDG uptake and CT calcifications. METHODS AND RESULTS: Fifty consecutive cancer patients (mean age, 68 +/- 8 years) had repeat PET/CT studies 8 to 26 months apart. PET, CT, and PET/CT images were retrospectively evaluated for vascular wall abnormalities and for interval changes in the thoracic and abdominal aortas, as well as in carotid and iliac arteries, classified as PET+/CT+, PET+/CT-, and PET-/CT+. There were 485 abnormal sites in the first study and 495 in the second. CT calcifications were found in 46 patients (92%) in the first study and in 47 (94%) in the second. Vascular wall FDG uptake was found in both studies in 37 patients (74%). The pattern changed in 57 of 119 PET+ sites (48%) in the second study compared with 15 of 366 PET- sites (4%) (P < .0001). In the second study new PET+ sites were observed in 36 of 111 sites (32%) versus new PET-/CT+ sites in 19 of 384 sites (5%) (P < .0001). CONCLUSIONS: Changes in vascular FDG activity and CT calcifications can be assessed by repeat PET/CT. FDG-avid foci may represent a dynamic process, transient inflammation, whereas CT calcifications may indicate stable atherosclerosis. These preliminary results support the need for further research.

Super-resolution in PET imaging.

This paper demonstrates a super-resolution method for improving the resolution in clinical positron emission tomography (PET) scanners. Super-resolution images were obtained by combining four data sets with spatial shifts between consecutive acquisitions and applying an iterative algorithm. Super-resolution attenuation corrected PET scans of a phantom were obtained using the two-dimensional and three-dimensional (3-D) acquisition modes of a clinical PET/computed tomography (CT) scanner (Discovery LS, GEMS). In a patient study, following a standard 18F-FDG PET/CT scan, a super-resolution scan around one small lesion was performed using axial shifts without increasing the patient radiation exposure. In the phantom study, smaller features (3 mm) could be resolved axially with the super-resolution method than without (6 mm). The super-resolution images had better resolution than the original images and provided higher contrast ratios in coronal images and in 3-D acquisition transaxial images. The coronal super-resolution images had superior resolution and contrast ratios compared to images reconstructed by merely interleaving the data to the proper axial location. In the patient study, super-resolution reconstructions displayed a more localized 18F-FDG uptake. A new approach for improving the resolution of PET images using a super-resolution method has been developed and experimentally confirmed, employing a clinical scanner. The improvement in axial resolution requires no changes in hardware.

Whole-body bone SPECT in breast cancer patients: the future bone scan protocol?

OBJECTIVE: The aim of the study was to compare the detectability rate of bone metastases in breast cancer patients using whole-body single-photon emission computed tomography (WB-SPECT) performed with a half-time acquisition algorithm with that of planar ± selected field-of-view SPECT [standard bone scintigraphy (BS)]. MATERIALS AND METHODS: Ninety-two consecutive breast cancer patients (age range 35-74 years) underwent planar BS followed by WB-SPECT (acquisition time 28 min). Clinical and imaging follow-up data from BS, 18F-FDG-PET/CT and CT were used as composite reference standards. Institutional review board approval was obtained. For a review of standard BS results, data from a selected SPECT field-of-view were extracted from the WB-SPECT when requested by the readers. Diagnostic confidence of interpretation criteria were defined using a five-point level-of-confidence grading scale of lesions. RESULTS: Bone metastases were diagnosed in 34 of 92 studies (37%). On patient-based analysis, the detectability rate of standard BS was 97% (33/34 patients) as compared with 100% for WB-SPECT (P=NS). On a lesion-based analysis, 268 foci were detected, including 124 metastases. Standard BS detected 195 lesions (73%; 99 metastases and 96 benign) and missed 73 lesions (25 metastases and 48 benign). WB-SPECT detected 266 lesions (99%; 124 metastases and 142 benign) and missed two benign foci because of SPECT reconstruction artefacts. The lesion-based detectability rate of metastases for standard BS was 80% compared with 100% for WB-SPECT (P<0.001). WB-SPECT was associated with a higher level of confidence compared with standard BS for both benign (P<0.01) and malignant lesions (P<0.05). CONCLUSION: WB-SPECT is a useful tool for skeletal assessment, showing good performance in comparison with standard BS in breast cancer patients, and may eliminate the need for an initial planar scan.

Prospective comparison of whole-body bone SPECT and sodium 18F-fluoride PET in the detection of bone metastases from breast cancer.

OBJECTIVE: The superiority of sodium F-fluoride PET (F-PET)/computed tomography (CT) over planar and single field-of-view single-photon emission computed tomography (SPECT) bone scintigraphy with Tc-methylene diphosphonate in bone metastases detection has been established. The present study prospectively compares whole-body Tc-methylene diphosphonate SPECT (WB-SPECT) and F-PET performance indices for the detection of bone metastases in breast cancer. METHODS: A total of 41 pairs of studies in female breast cancer patients (average age 58 years, range 30-75) were included. Half-time WB-SPECT and F-PET/CT were performed at a 4-day average interval (range 0-36 days), with subsequent fusion of CT to WB-SPECT. Two readers independently interpreted the studies, with differences resolved by consensus. Composite gold standard included the CT component of the F-PET/CT study with follow-up CT, MRI, F-fluoro-deoxyglucose-PET/CT, and bone scans. RESULTS: On patient-based analysis, metastases were diagnosed in 21 patients, with 19 patients detected by WB-SPECT and 21 with F-PET, the latter being the only modality to detect a single metastasis in two patients. The sensitivity of WB-SPECT and F-PET was 90 and 100% (P=NS), and the specificity were 95 and 85%, respectively (P=NS). On lesion-based analysis, 284 total sites of increased uptake were found. WB-SPECT detected 171/284 (60%) and F-PET 268/284 (94%) lesions, with good interobserver agreement for WB-SPECT (κ=0.679) and excellent agreement for F-PET (κ=0.798). The final analysis classified 204 lesions as benign and 80 as metastases. WB-SPECT identified 121 benign and 50 malignant sites compared with 192 and 76, respectively, for F-PET. WB-SPECT and F-PET had a sensitivity of 63 vs. 95%, P-value of less than 0.001, and a specificity of 97 vs. 96% (P=NS), respectively, on lesion-based analysis. CONCLUSION: F-PET had higher sensitivity for the diagnosis of bone metastases from breast cancer compared with WB-SPECT, showing a statistically significant 32% increase on lesion-based analysis.

PET/CT detection of unexpected gastrointestinal foci of 18F-FDG uptake: incidence, localization patterns, and clinical significance.

UNLABELLED: Precise PET/CT localization of focal (18)F-FDG uptake in the gastrointestinal tract (GIT) may exclude malignancy in sites of physiologic activity but may also induce false-negative reports for malignant or premalignant lesions. The purpose of the present study was to retrospectively evaluate the nature and significance of unexpected focal (18)F-FDG uptake localized by PET/CT within the GIT. METHODS: The files of 4,390 patients referred for (18)F-FDG PET/CT were retrospectively reviewed. The incidence of studies showing unexpected focal uptake of (18)F-FDG localized by PET/CT to the GIT was determined. The position of these foci along the GIT and their intensity were recorded. The etiology of the findings was confirmed histologically or by long-term follow-up. RESULTS: Unexpected focal (18)F-FDG uptake in the GIT was found in 58 patients (1.3%). Follow-up data were available for 34 of these patients, including 4 with sites in the stomach, 2 in the small bowel, and 28 in the colon. GIT-related disease was confirmed in 24 patients (71%). There were 11 malignant tumors, 9 premalignant lesions, and 4 benign processes including 2 benign polyps, 1 case of active gastritis, and 1 abscess of the sigmoid. Ten patients (29%) had no further evidence of GIT abnormality, and the suggestive sites were considered to be physiologic uptake. Maximal standardized uptake value was 17.3 +/- 10.2 in malignant lesions, 14.0 +/- 10.5 in premalignant lesions, 18.0 +/- 12.1 in benign lesions, and 11.1 +/- 7.4 in foci of physiologic (18)F-FDG uptake in the GIT, with no statistically significant difference among the 4 subgroups. CONCLUSION: Incidental focal (18)F-FDG uptake localized by PET/CT within the GIT is of clinical significance in most patients. These findings should be followed up with appropriate invasive procedures guided by hybrid imaging results.

Metabolic PET/CT-guided lung lesion biopsies: impact on diagnostic accuracy and rate of sampling error.

UNLABELLED: CT-guided fine-needle aspiration (FNA) of lung lesions is subject to sampling errors. The current study assessed whether information provided by (18)F-FDG PET/CT will decrease the false-negative (FN) rate and thus improve the accuracy of CT-guided FNA. METHODS: Data from 311 consecutive patients with lung nodules who underwent (18)F-FDG PET/CT and CT-guided FNA within an interval of less than 30 d were retrospectively assessed. In-house-developed software was used to register CT images performed for the FNA procedure (CT FNA) with corresponding slices of the PET/CT study. The quality of registration was rated on a scale of 1 (excellent) to 5 (misregistration). Only cases scored 1 or 2 were further evaluated. The software provided the highest standardized uptake value (SUV) within the lesion and at the location of the tip of the aspirating needle. The distance between the tip and the area with the highest SUV within the lesion was measured. The mean distance from the tip of the needle to the focus with the highest SUV, as well as the mean difference between the maximum SUV in the whole lesion and at the needle tip, was calculated and compared for cases with true-positive (TP) and FN FNA results. Anatomic and metabolic parameters of lesions included in these 2 groups were also compared. RESULTS: There were 267 patients (86%) with score 1 or 2 registration quality for CT FNA and PET/CT/CT images, including 179 TP (67%), 5 false-positive (FP, 2%), 49 true-negative (TN, 18%), and 34 FN (13%) FNA results. The distance between the location of the needle tip and the focus with the highest SUV in the lesion was significantly greater in the FN group (15.4 ± 14 mm) than in the TP group (5.9 ± 13.4 mm, P < 0.001). The maximum SUV at the location of the aspirating needle tip was significantly higher in the TP group, at 6.4 ± 6.4, than in the FN group, at 4 ± 4.7 (P < 0.05). CONCLUSION: The present results demonstrate a relationship between the degree of metabolism at the site of tissue-sampling aspiration in lung lesions and the accuracy of FNA results. Anatomy- and metabolism-based FNA guidance using information provided by both (18)F-FDG PET and CT may improve the accuracy of histologic examinations, decrease the rate of FN results, and thus increase the probability of achieving a definitive diagnosis.