Radionuclide shuntography for cerebrospinal fluid shunt flow evaluation in adults.

OBJECTIVE: Radionuclide shuntography (RS) performed using 99mTc-DTPA injected into the reservoir of CSF shunts enables evaluation of CSF flow for suspected shunt malfunctions. The goal of this study was to report the authors' institutional experience with RS and evaluate its utility and associated complications. METHODS: The authors retrospectively reviewed all RS studies performed between November 2003 and June 2022. Patients with shunted hydrocephalus who were ≥ 18 years of age were included. Patients undergoing RS for evaluation of Ommaya reservoirs were excluded. Demographics, hydrocephalus etiology, presenting symptoms, study results, subsequent management, complications, and intraoperative diagnoses were recorded. Chi-square tests were reported for categorical variables and standard 2 × 2 contingency methods were used for sensitivity/specificity analysis. RESULTS: The authors identified 211 RS procedures performed in 142 patients. The mean age at procedure was 55.6 ± 20.9 years (mean ± SD). Normal pressure hydrocephalus was the most common hydrocephalus etiology (37.0%), followed by congenital malformations (26.1%) and idiopathic intracranial hypertension (15.6%). Successful radionuclide injection was achieved in 207 studies (98.1%). Shunt patency was confirmed in 63.8% of successful injections, whereas malfunction was demonstrated in 27.1% and abnormally slow flow was seen in 9.2%. RS studies demonstrating shunt malfunction were more likely to result in subsequent revisions than were studies showing patency (86.6% vs 2.9%; p < 0.0001). The overall sensitivity and specificity of RS for detecting shunt malfunction was 92.3% and 96.2%, respectively. The median follow-up time was 29 months, with 151 cases having ≥ 6 months of follow-up. There were no complications or infections attributable to RS in this cohort. CONCLUSIONS: RS is a useful and safe tool in the workup of shunt malfunction.

The comorbidity of depression and neurocognitive disorder in persons with HIV infection: call for investigation and treatment.

Depression and neurocognitive disorder continue to be the major neuropsychiatric disorders affecting persons with HIV (PWH). The prevalence of major depressive disorder is two to fourfold higher among PWH than the general population (∼6.7%). Prevalence estimates of neurocognitive disorder among PWH range from 25 to over 47% - depending upon the definition used (which is currently evolving), the size of the test battery employed, and the demographic and HIV disease characteristics of the participants included, such as age range and sex distribution. Both major depressive disorder and neurocognitive disorder also result in substantial morbidity and premature mortality. However, though anticipated to be relatively common, the comorbidity of these two disorders in PWH has not been formally studied. This is partly due to the clinical overlap of the neurocognitive symptoms of these two disorders. Both also share neurobehavioral aspects - particularly apathy - as well as an increased risk for non-adherence to antiretroviral therapy. Shared pathophysiological mechanisms potentially explain these intersecting phenotypes, including neuroinflammatory, vascular, and microbiomic, as well as neuroendocrine/neurotransmitter dynamic mechanisms. Treatment of either disorder affects the other with respect to symptom reduction as well as medication toxicity. We present a unified model for the comorbidity based upon deficits in dopaminergic transmission that occur in both major depressive disorder and HIV-associated neurocognitive disorder. Specific treatments for the comorbidity that decrease neuroinflammation and/or restore associated deficits in dopaminergic transmission may be indicated and merit study.

Potential Prognostic Value of Native T1 in Pulmonary Hypertension Patients.

Native T1, extracellular volume fraction (ECV), and late gadolinium enhancement (LGE) characterize myocardial tissue and relate to patient prognosis in a variety of diseases, including pulmonary hypertension. The purpose of this study was to evaluate if left ventricle (LV) fibrosis measurements have prognostic value for cardiac outcomes in pulmonary hypertension subgroups. 54 patients with suspected pulmonary hypertension underwent right-heart catheterization and were classified into pulmonary hypertension subgroups: pre-capillary component (PreCompPH) and isolated post-capillary (IpcPH). Cardiac magnetic resonance imaging (MRI) scans were performed with the acquisition of balanced cine steady-state free precession, native T1, and LGE pulse sequences to measure cardiac volumes and myocardial fibrosis. Associations between cardiac events and cardiac MRI measurements were analyzed within PreCompPH and IpcPH patients. IpcPH: LV native T1 was higher in patients who experienced a cardiac event within two years vs. those who did not. In patients with LV native T1 > 1050 ms, the rate of cardiac events was higher. ECV and quantitative LGE did not differ between groups. PreCompPH: native T1, ECV, and quantitative/qualitative LGE did not differ between patients who experienced a cardiac event within two years vs. those who did not. LV native T1 may have potential value for forecasting cardiac events in IpcPH, but not in PreCompPH, patients.

Systolic reverse flow derived from 4D flow cardiovascular magnetic resonance in bicuspid aortic valve is associated with aortic dilation and aortic valve stenosis: a cross sectional study in 655 subjects.

BACKGROUND: Bicuspid aortic valve (BAV) disease is associated with increased risk of aortopathy. In addition to current intervention guidelines, BAV mediated changes in aortic 3D hemodynamics have been considered as risk stratification measures. We aimed to evaluate the association of 4D flow cardiovascular magnetic resonance (CMR) derived voxel-wise aortic reverse flow with aortic dilation and to investigate the role of aortic valve regurgitation (AR) and stenosis (AS) on reverse flow in systole and diastole. METHODS: 510 patients with BAV (52 ± 14 years) and 120 patients with trileaflet aortic valve (TAV) (61 ± 11 years) and mid-ascending aorta diameter (MAAD) > 35 mm who underwent CMR including 4D flow CMR were retrospectively included. An age and sex-matched healthy control cohort (n = 25, 49 ± 12 years) was selected. Voxel-wise reverse flow was calculated in the aorta and quantified by the mean reverse flow in the ascending aorta (AAo) during systole and diastole. RESULTS: BAV patients without AS and AR demonstrated significantly increased systolic and diastolic reverse flow (222% and 13% increases respectively, p < 0.01) compared to healthy controls and also had significantly increased systolic reverse flow compared to TAV patients with aortic dilation (79% increase, p < 0.01). In patients with isolated AR, systolic and diastolic AAo reverse flow increased significantly with AR severity (c = - 83.2 and c = - 205.6, p < 0.001). In patients with isolated AS, AS severity was associated with an increase in both systolic (c = - 253.1, p < 0.001) and diastolic (c = - 87.0, p = 0.02) AAo reverse flow. Right and left/right and non-coronary fusion phenotype showed elevated systolic reverse flow (> 17% increase, p < 0.01). Right and non-coronary fusion phenotype showed decreased diastolic reverse flow (> 27% decrease, p < 0.01). MAAD was an independent predictor of systolic (p < 0.001), but not diastolic, reverse flow (p > 0.1). CONCLUSION: 4D flow CMR derived reverse flow associated with BAV was successfully captured even in the absence of AR or AS and in comparison to TAV patients with aortic dilation. Diastolic AAo reverse flow increased with AR severity while AS severity strongly correlated with increased systolic reverse flow in the AAo. Additionally, increasing MAAD was independently associated with increasing systolic AAo reverse flow. Thus, systolic AAo reverse flow may be a valuable metric for evaluating disease severity in future longitudinal outcome studies.

A Framework for Harmonization of Radiomics Data for Multicenter Studies and Clinical Trials.

PURPOSE: Variability in computed tomography images intrinsic to individual scanners limits the application of radiomics in clinical and research settings. The development of reproducible and generalizable radiomics-based models to assess lesions requires harmonization of data. The purpose of this study was to develop, test, and analyze the efficacy of a radiomics data harmonization model. MATERIALS AND METHODS: Radiomic features from biopsy-proven untreated hepatic metastasis (N = 380) acquired from 167 unique patients with pancreatic, colon, and breast cancers were analyzed. Radiomic features from volume-match 551 samples of normal liver tissue and 188 hepatic cysts were included as references. A novel linear mixed effect model was used to identify effects associated with lesion size, tissue type, and scanner model. Six separate machine learning models were then used to test the effectiveness of radiomic feature harmonization using multivariate analysis. RESULTS: Proposed model identifies and removes scanner-associated effects while preserving cancer-specific functional dependence of radiomic features on the tumor size. Data harmonization improves the performance of classification models by reducing the scanner-associated variability. For example, the multiclass logistic regression model, LogitBoost, demonstrated the improvement in sensitivity in the range from 15% to 40% for each type of liver metastasis, whereas the overall model accuracy and the kappa coefficient increased by 5% and 8% accordingly. CONCLUSION: The model removed scanner-associated effects while preserving cancer-specific functional dependence of radiomic features.

Role of hepatic metastatic lesion size on inter-reader reproducibility of CT-based radiomics features.

OBJECTIVES: To evaluate the effect of hepatic metastatic lesion size on inter-reader reproducibility of CT-based 2D radiomics imaging features. METHODS: Computerized tomography (CT) scans of 59 liver metastases from 34 patients with colorectal cancer were evaluated. Image segmentation was performed manually by three readers blinded to each other's results. For each radiomics feature, we created two datasets by sorting measurements according to size, i.e., (i) from the smallest to the largest lesion and (ii) from the largest to the smallest lesion. The Lin concordance correlation coefficient (CCC) was employed to analyze the reproducibility of radiomics features. In particular, the CCC was computed as a function of a number of elements in the dataset, by gradually adding lesions from each sorted dataset. To evaluate the effect of lesion size, we analyzed the difference between these two functions thus assessing the contribution of small and large lesions into the reproducibility of radiomics features. RESULTS: Inter-reader reproducibility of CT-based 2D radiomics features assessed using Lin's CCC demonstrates tumor-size dependence. For example, the Lin CCC for GLCM contrast equals 0.88 (95% C.I. 0.84 to 0.92, p < 0.003) and could change by an additional + / - 0.06 depending on the presence of large or small lesions. CONCLUSIONS: Groups of "large" and "small" lesions show different inter-reader reproducibility. The inter-reader reproducibility from the mixed group consisting of "large" and "small" lesions depends on the lesion-size distribution and can vary widely. This finding could partially explain variability in reproducibility of radiomics features in the literature. KEY POINTS: • Groups of "large" and "small" lesions show different inter-reader reproducibility. • The inter-reader reproducibility from the mixed group consisting of "large" and "small" lesions depends on the lesion-size distribution.

Left Ventricular Fibrosis Assessment by Native T1, ECV, and LGE in Pulmonary Hypertension Patients.

Cardiac magnetic resonance imaging (MRI) is emerging as an alternative to right heart catheterization for the evaluation of pulmonary hypertension (PH) patients. The aim of this study was to compare cardiac MRI-derived left ventricle fibrosis indices between pre-capillary PH (PrePH) and isolated post-capillary PH (IpcPH) patients and assess their associations with measures of ventricle function. Global and segmental late gadolinium enhancement (LGE), longitudinal relaxation time (native T1) maps, and extracellular volume fraction (ECV) were compared among healthy controls (N = 25; 37% female; 52 ± 13 years), PH patients (N = 48; 60% female; 60 ± 14 years), and PH subgroups (PrePH: N = 29; 65% female; 55 ± 12 years, IpcPH: N = 19; 53% female; 66 ± 13 years). Cardiac cine measured ejection fraction, end diastolic, and end systolic volumes and were assessed for correlations with fibrosis. LGE mural location was qualitatively assessed on a segmental basis for all subjects. PrePH patients had elevated (apical-, mid-antero-, and mid-infero) septal left ventricle native T1 values (1080 ± 74 ms, 1077 ± 39 ms, and 1082 ± 47 ms) compared to IpcPH patients (1028 ± 53 ms, 1046 ± 36 ms, 1051 ± 44 ms) (p < 0.05). PrePH had a higher amount of insertional point LGE (69%) and LGE patterns characteristic of non-vascular fibrosis (77%) compared to IpcPH (37% and 46%, respectively) (p < 0.05; p < 0.05). Assessment of global LGE, native T1, and ECV burdens did not show a statistically significant difference between PrePH (1.9 ± 2.7%, 1056.2 ± 36.3 ms, 31.2 ± 3.7%) and IpcPH (2.7 ± 2.7%, 1042.4 ± 28.1 ms, 30.7 ± 4.7%) (p = 0.102; p = 0.229 p = 0.756). Global native T1 and ECV were higher in patients (1050.9 ± 33.8 and 31.0 ± 4.1%) than controls (28.2 ± 3.7% and 1012.9 ± 29.4 ms) (p < 0.05). Cardiac MRI-based tissue characterization may augment understanding of cardiac involvement and become a tool to facilitate PH patient classification.

Timing of Intubation in Coronavirus Disease 2019: A Study of Ventilator Mechanics, Imaging, Findings, and Outcomes.

OBJECTIVES: Determine the variation in outcomes and respiratory mechanics between the subjects who are intubated earlier versus later in their coronavirus disease 2019 course. DESIGN: Retrospective cohort study. SETTING: Northwestern Memorial Hospital ICUs. PATIENTS: All patients intubated for coronavirus disease 2019 between March 2020 and June 2020. INTERVENTIONS: Patients were stratified by time to intubation: 30 subjects were intubated 4-24 hours after presentation and 24 subjects were intubated 5-10 days after presentation. Baseline characteristics, hospitalization, ventilator mechanics, and outcomes were extracted and analyzed. Ten clinically available CT scans were manually reviewed to identify evidence of pulmonary vascular thrombosis and intussusceptive angiogenesis. MEASUREMENTS AND MAIN RESULTS: Median time from symptom onset to intubation was significantly different between the early and late intubation cohorts, with the latter being intubated later in the course of their illness (7.9 vs 11.8 d; p = 0.04). The early intubation cohort had a lower mortality rate than the late intubation cohort (6% vs 30%, p < 0.001) without significantly different respiratory mechanics at the time of intubation. The late intubation cohort was noted to have higher dead space ratio (0.40 vs 0.52; p = 0.03). On review of CT scans, the late intubation cohort also had more dilated peripheral segments on imaging (two segments vs five segments). CONCLUSIONS: The question as to whether delaying intubation is beneficial or harmful for patients with coronavirus disease 2019-induced hypoxemic respiratory failure has yet to be answered. As our approaches to coronavirus disease 2019 continue to evolve, the decision of timing of intubation remains paramount. Although noninvasive ventilation may allow for delaying intubation, it is possible that there are downstream effects of delayed intubation that should be considered, including the potential for pulmonary vascular thrombosis and intussusceptive angiogenesis with delayed intubation.

Evaluation of image quality of wideband single-shot late gadolinium-enhancement MRI in patients with a cardiac implantable electronic device.

INTRODUCTION: While wideband segmented, breath-hold late gadolinium-enhancement (LGE) cardiovascular magnetic resonance (CMR) has been shown to suppress image artifacts associated with cardiac-implanted electronic devices (CIEDs), it may produce image artifacts in patients with arrhythmia and/or dyspnea. Single-shot LGE is capable of suppressing said artifacts. We sought to compare the performance of wideband single-shot free-breathing LGE against the standard and wideband-segmented LGEs in CIED patients. METHODS AND RESULTS: We retrospectively identified all 54 consecutive patients (mean age: 61 ± 15 years; 31% females) with CIED who had undergone CMR with standard segmented, wideband segmented, and/or wideband single-shot LGE sequences as part of quality assurance for determining best clinical practice at 1.5 T. Two raters independently graded the conspicuity of myocardial scar or normal myocardium and the presence of device artifact level on a 5-point Likert scale (1: worst; 3: acceptable; 5: best). Summed visual score (SVS) was calculated as the sum of conspicuity and artifact scores (SVS ≥ 6 defined as diagnostically interpretable). Median conspicuity and artifact scores were significantly better for wideband single-shot LGE (F = 24.2, p < .001) and wideband-segmented LGE (F = 20.6, p < .001) compared to standard-segmented LGE. Among evaluated myocardial segments, 72% were deemed diagnostically interpretable-defined as SVS ≥ 6-for standard-segmented LGE, 89% were deemed diagnostically interpretable for wideband-segmented LGE, and 94% segments were deemed diagnostically interpretable for wideband single-shot LGE. CONCLUSIONS: Wideband single-shot LGE and wideband-segmented LGE produced similarly improved image quality compared to standard LGE.

Accelerated 3D Left Atrial Late Gadolinium Enhancement in Patients with Atrial Fibrillation at 1.5 T: Technical Development.

PURPOSE: To develop an accelerated three-dimensional (3D) late gadolinium enhancement (LGE) pulse sequence using balanced steady-state free precession readout with stack-of-stars k-space sampling and extra motion-state golden-angle radial sparse parallel (XD-GRASP) reconstruction and test the performance for detecting atrial scar and fibrosis in patients with atrial fibrillation (AF). MATERIALS AND METHODS: Twenty-five patients with AF (20 paroxysmal and five persistent; 65 years ± 7 [standard deviation]; 18 men) were imaged at 1.5 T using the proposed LGE sequence with 1.3 mm × 1.3 mm × 2-mm spatial resolution and predictable imaging time. The resulting images were compared with historic images of 25 patients with AF (18 paroxysmal and seven persistent; 67 years ± 10; 14 men) obtained using a reference 3D left atrial (LA) LGE sequence with 1.3 mm × 1.3 mm × 2.5-mm spatial resolution. Two readers visually graded the 3D LGE images (conspicuity, artifact, noise) on a five-point Likert scale (1 = worst, 3 = acceptable, 5 = best), in which the summed visual score (SVS) of 9 or greater was defined as clinically acceptable. Appropriate statistical analyses (Cohen κ coefficient, Mann-Whitney U test, t tests, and intraclass correlation) were performed, where a P value < .05 was considered significant. RESULTS: Mean imaging time was significantly shorter (P < .01) for the proposed pulse sequence (5.9 minutes ± 1.3) than for the reference pulse sequence (10.6 minutes ± 2). Median SVS was significantly higher (P < .01) for the proposed (SVS = 11) than reference (SVS = 9.5) 3D LA LGE images. Interrater reproducibility in visual scores was higher for the proposed (κ = 0.78-1) than reference 3D LA LGE (κ = 0.44-0.75). Intrareader repeatability in fibrosis quantification was higher for the reference cohort (intraclass correlation coefficient [ICC] = 0.94) than the prospective cohort (ICC = 0.79). CONCLUSION: The proposed 3D LA LGE method produced clinically acceptable image quality with 1.5 mm × 1.5 mm × 2-mm nominal spatial resolution and 6-minute predictable imaging time for quantification of LA scar and fibrosis in patients with AF. Supplemental material is available for this article. © RSNA, 2020.

Rapid Reconstruction of Four-dimensional MR Angiography of the Thoracic Aorta Using a Convolutional Neural Network.

PURPOSE: To implement an integrated reconstruction pipeline including a graphics processing unit (GPU)-based convolutional neural network (CNN) architecture and test whether it reconstructs four-dimensional non-Cartesian, non-contrast material-enhanced MR angiographic k-space data faster than a central processing unit (CPU)-based compressed sensing (CS) reconstruction pipeline, without significant losses in data fidelity, summed visual score (SVS), or arterial vessel-diameter measurements. MATERIALS AND METHODS: Raw k-space data of 24 patients (18 men and six women; mean age, 56.8 years ± 11.8 [standard deviation]) suspected of having thoracic aortic disease were used to evaluate the proposed reconstruction pipeline derived from an open-source three-dimensional CNN. For training, 4800 zero-filled images and the corresponding CS-reconstructed images from 10 patients were used as input-output pairs. For testing, 6720 zero-filled images from 14 different patients were used as inputs to a trained CNN. Metrics for evaluating the agreement between the CNN and CS images included reconstruction times, structural similarity index (SSIM) and normalized root-mean-square error (NRMSE), SVS (3 = nondiagnostic, 9 = clinically acceptable, 15 = excellent), and vessel diameters. RESULTS: The mean reconstruction time was 65 times and 69 times shorter for the CPU-based and GPU-based CNN pipelines (216.6 seconds ± 40.5 and 204.9 seconds ± 40.5), respectively, than for CS (14 152.3 seconds ± 1708.6) (P < .001). Compared with CS as practical ground truth, CNNs produced high data fidelity (SSIM = 0.94 ± 0.02, NRMSE = 2.8% ± 0.4) and not significantly different (P = .25) SVS and aortic diameters, except at one out of seven locations, where the percentage difference was only 3% (ie, clinically irrelevant). CONCLUSION: The proposed integrated reconstruction pipeline including a CNN architecture is capable of rapidly reconstructing time-resolved volumetric cardiovascular MRI k-space data, without a significant loss in data quality, thereby supporting clinical translation of said non-contrast-enhanced MR angiograms. Supplemental material is available for this article. © RSNA, 2020.

Remodeling Failing Human Myocardium With Hybrid Cell/Matrix and Transmyocardial Revascularization.

Given the limited treatment options for advanced heart failure, the intrinsic regenerative properties of stem cells have been evaluated for myocardial remodeling. Previous stem cells techniques for myocardiocyte remodeling have been limited by the low cellular retention. Presented is a hybrid approach for remodeling infarcted myocardium through implantation of allogeneic human amniotic fluid-derived mesenchymal stem cells within micronized human allograft-derived liquid matrix during the performance of transmyocardial revascularization (TMR). Given the induced increase in vascular density from TMR, we hypothesize that it may serve as a therapeutic delivery system for stem cell placement into damaged myocardium. We present a patient with ischemic cardiomyopathy and refractory angina, who clinically improved after this hybrid therapy of intraoperative TMR and placement of amniotic fluid-derived mesenchymal stem cells and liquid matrix within the TMR channels. Noninvasive testing of myocardial viability biomarkers utilizing both cardiac magnetic resonance imaging and thallium imaging supported the clinical improvement in cardiac symptom may be related to ventricular remodeling in a region of infarct with subsequent functional improvement.

Atlas of Extraosseous Findings Detected by 18F-NaF PET/CT Bone Scan.

F-NaF PET/CT is an evolving technique that provides high sensitivity for detection of osseous metastases. In addition to detecting pathological osseous lesions, F uptake is occasionally detected in extraosseous lesions. However, reporting of extraosseous uptake in the literature is limited, and the increasing use of F-NaF PET/CT dictates that interpreting physicians learn to recognize extraosseous findings. An atlas of extraosseous findings detected by F-NaF PET/CT is presented, which includes cases under 2 broad categories: nonneoplastic and neoplastic.

Segmentation of the right ventricle in four chamber cine cardiac MR images using polar dynamic programming.

The four chamber plane is currently underutilized in the right ventricular segmentation community. Four chamber information can be useful to determine ventricular short axis stacks and provide a rough estimate of the right ventricle in short axis stacks. In this study, we develop and test a semi-automated technique for segmenting the right ventricle in four chamber cine cardiac magnetic resonance images. The three techniques that use minimum cost path algorithms were used. The algorithms are: Dijkstra's shortest path algorithm (Dijkstra), an A* algorithm that uses length, curvature and torsion into an active contour model (ALCT), and a variation of polar dynamic programming (PDP). The techniques are evaluated against the expert traces using 175 cardiac images from 7 patients. The evaluation first looks at mutual overlap metrics and then focuses on clinical measures such as fractional area change (FAC). The mean mutual overlap between the physician's traces ranged from 0.85 to 0.88. Using as reference physician 1's landmarks and traces (i.e., comparing the traces from physician 1 to the semi-automated segmentation using physician 1's landmarks), the PDP algorithm has a mean mutual overlap of 0.8970 compared to 0.8912 for ALCT and 0.8879 for Dijkstra. The mean mutual overlap between the BP regions generated by physician 1 and physician 2 landmarks are 0.9674, 0.9605 and 0.9531 for PDP, ALCT and Dijkstra, respectively. The FAC correlation coefficient between the physician's traces ranged from 0.73 to 0.93.

Incidence of Brain Metastases on Follow-up 18F-FDG PET/CT Scans of Non-Small Cell Lung Cancer Patients: Should We Include the Brain?

The brain is the most common site of distant metastasis from lung cancer. Thus, MRI of the brain at initial staging is routinely performed, but if this examination is negative a follow-up examination is often not performed. This study evaluates the incidence of asymptomatic brain metastases in non-small cell lung cancer patients detected on follow-up 18F-FDG PET/CT scans. Methods: In this Institutional Review Board-approved retrospective review, all vertex to thigh 18F-FDG PET/CT scans in patients with all subtypes of lung cancer from August 2014 to August 2016 were reviewed. A total of 1,175 18F-FDG PET/CT examinations in 363 patients were reviewed. Exclusion criteria included brain metastases on initial staging, histologic subtype of small-cell lung cancer, and no follow-up 18F-FDG PET/CT examinations. After our exclusion criteria were applied, a total of 809 follow-up 18F-FDG PET/CT scans in 227 patients were included in the final analysis. The original report of each 18F-FDG PET/CT study was reviewed for the finding of brain metastasis. The finding of a new brain metastasis prompted a brain MRI, which was reviewed to determine the accuracy of the 18F-FDG PET/CT. Results: Five of 227 patients with 809 follow-up 18F-FDG PET/CT scans reviewed were found to have incidental brain metastases. The mean age of the patients with incidental brain metastasis was 68 y (range, 60-77 y). The mean time from initial diagnosis to time of detection of incidental brain metastasis was 36 mo (range, 15-66 mo). When MRI was used as the gold standard, our false-positive rate was zero. Conclusion: By including the entire head during follow-up 18F-FDG PET/CT scans of patients with non-small cell lung cancer, brain metastases can be detected earlier while still asymptomatic. But, given the additional scan time, radiation, and low incidence of new brain metastases in asymptomatic patients, the cost-to-benefit ratio should be weighed by each institution.

Punctate Radiation Dermatitis of the Foot and Ankle Caused by Distal Embolization of 90Y Microspheres During Liver Directed Therapy.

A 41-year-old man with gastric adenocarcinoma presented with hepatic metastases. The metastases were refractory to systemic chemotherapy, so radioembolization with Y microspheres was performed. Because of stasis or saturation of the tumor with embolic particles, 79% of the microspheres were injected. At follow-up, the patient complained of "red bumps" that had developed on his right foot/ankle the day after the radioembolization. Because a portion of the dose was still in the catheter when withdrawn from the right femoral artery, the interventional radiologist used a Geiger counter to confirm radioactivity in the cutaneous lesions and thus the distal embolization of the microspheres.

FDG-PET/CT for Monitoring Response of Melanoma to the Novel Oncolytic Viral Therapy Talimogene Laherparepvec.

61-year-old woman with stage IIIa (T3a N1a M0) left lower leg melanoma with lesions suggestive of in-transit metastases 8 months following wide local excision and femoral nodal dissection. FDG-PET/CT demonstrated 5 FDG-avid in-transit nodal metastases in the distal left leg, confirmed on biopsy. Talimogene laherparepvec (T-VEC) oncolytic immunotherapy consisting of intralesional injections of modified herpes simplex virus-expressing granulocyte-macrophage colony-stimulating factor was completed over 6 months. Subsequent FDG-PET/CT demonstrated reduced or resolved FDG activity in the treated in-transit metastases and a new FDG-avid left thigh in-transit metastasis. FDG-PET/CT can monitor response to T-VEC and potentially other novel viral immunotherapies.

Optimal Time Points for Scintigraphic Imaging of Pleuroperitoneal Shunts.

OBJECTIVE: Nuclear imaging can confirm pleuroperitoneal shunt as the cause of pleural effusion. No society guidelines exist for scintigraphic pleuroperitoneal shunt detection. Our institutional protocol was evaluated to determine optimal imaging time points for shunt detection. METHODS: Pleuroperitoneal shunt studies over 4 years were blindly reviewed by 2 nuclear radiologists. Data from blinded review included presence or absence of pleuroperitoneal shunt, laterality of shunt and time points for shunt detection. RESULTS: Chart review yielded 30 studies. Three cases were excluded because of improper injection. Imaging was positive for pleuroperitoneal shunt in 81% (22/27) of cases. In positive cases, activity was identified in the right hemithorax in 82% (18/22), left hemithorax in 9% (2/22), and bilaterally in 9% (2/22). One-hour imaging demonstrated 91% (20/22) of positive cases. The remaining 2 positive cases were negative at 1 hour but positive after 4 hours. No study was negative at 1 and 4 hours and positive at 24 hours. All negative cases (5/27) were confirmed on 24-hour imaging. CONCLUSIONS: The majority of positive pleuroperitoneal shunt examinations will demonstrate activity in the right hemithorax on 1-hour imaging. Although no case was negative at 1 and 4 hours and positive at 24 hours, imaging at 24 hours may still be necessary to confirm absence of shunt. Therefore, optimal imaging time points consist of early 1-hour and delayed 24-hour images if the 1-hour time point was negative. The 4-hour time point may be considered optional, thereby potentially optimizing patient safety and resource utilization.

Pitfalls in the Performance and Interpretation of Scintigraphic Imaging for Pleuroperitoneal Shunt.

Ascites can cause pleural effusions when the peritoneal fluid crosses the diaphragm through a pleuroperitoneal shunt in the setting of hepatic cirrhosis (hepatic hydrothorax) or malignant ascites. Scintigraphic imaging for pleuroperitoneal shunt requires intraperitoneal injection of Tc-SC or Tc-macroaggregated albumin followed by planar imaging of the chest and abdomen. Pleuroperitoneal shunt is confirmed by identifying radiotracer crossing the diaphragm from the peritoneal to pleural space. An atlas of pleuroperitoneal shunt imaging pitfalls is presented to facilitate optimal performance and interpretation of nuclear pleuroperitoneal shunt examinations. Examples include cases of nondiagnostic radiotracer injections, processing errors, and nontarget uptake.