Spontaneous Regression of Primary Cutaneous Diffuse Large B-Cell Lymphoma on Sequential FDG PET.

ABSTRACT: Primary cutaneous diffuse large B-cell lymphoma, leg type is a rare, aggressive lymphoma characterized by skin involvement predominantly in the lower extremities. We present a case of an elderly woman with pathology diagnosis of primary cutaneous diffuse large B-cell lymphoma, leg type with spontaneous regression without systematic therapy documented by sequential FDG PET scans and clinical follow-up.

Differentiating primary from secondary lung cancer with FDG PET/CT and extra-pulmonary tumor grade.

OBJECTIVE: Assess feasibility of differentiating primary from secondary lung cancer in patients with a solid solitary malignant pulmonary lesion (SMPL) and a previously resected extrapulmonary tumor. METHODS: Patients with pathology proven primary or secondary lung cancer from a solitary pulmonary lesion and known histopathology of extrapulmonary tumor were included. Patients with a small pulmonary lesion size, multiple malignant pulmonary nodules or an active infectious/inflammatory process were excluded. Extrapulmonary tumor grade was categorized as low, intermediate and high and was matched to FDG uptake intensity of SMPL, with FDG uptake range (SMPL/Liver SUVmax) of <0.9 for low, 0.91-1.99 for intermediate and >2.0 for high extrapulmonary tumor grade. RESULTS: Of 274 patients, 62 met the study criteria. 46 are primary and 16 are secondary lung cancer. There are 19 low, 27 intermediate and 16 high grade extrapulmonary tumors. Mean SMPL SUVmax is 8.2 ± 4.5 and SMPL/liver SUVmax is 2.4 ± 1.4. There are 37 cases (60%) with mismatched results (e.g., low FDG SMPL with intermediate or high grade extrapulmonary tumor or vice versa) and 25 matched cases (40%) that are inconclusive (e.g., low FDG with low tumor grade or high FDG with high tumor grade). Of the mismatched cases, we correctly predicted 30 cases (81%) as primary lung cancers. CONCLUSION: A mismatch between the SMPL SUVmax and the extrapulmonary tumor grade could be used to differentiate a primary lung cancer from a metastasis with reasonable accuracy. Our preliminary results support the hypothesis that FDG uptake intensity of a metastatic pulmonary lesion mirrors the tumor aggressiveness of its extrapulmonary neoplasm of origin.

Duration of Breastfeeding Interruption in Nuclear Medicine Procedures.

The recommendation for the duration of breastfeeding interruption after radiopharmaceutical administration has not been standardized and varies among the guidance documents and publications in the literature. Methods: A working group consisting of 3 staff physicians, 2 fellows, and 2 technologists was designated to update the institutional recommendations on breastfeeding interruption based on the review of the guidance documents and the literature. Results: Our institutional recommendations on the duration of breastfeeding interruption for 54 radiopharmaceuticals are presented in 4 summary tables. For completeness, we also include other radiopharmaceuticals with available information. Conclusion: The detailed recommendation summary on breastfeeding might be helpful to other centers.

Anti-inflammatory effect of biologic therapy in patients with psoriatic disease: A prospective cohort FDG PET study.

AIM: The aim of the study was to evaluate the changes in central vascular inflammation measured by FDG PET and myocardial blood flow reserve (MFR) determined by 82Rb PET following therapy with biologic agents for 6 months in patients with psoriatic arthritis (PsA) and/or cutaneous psoriasis (PsO) (group 1) and compare with PsO subjects receiving non-biologic therapy (group 2) and controls (group 3). METHODS AND RESULTS: Target-to-background ratio (TBR) by FDG PET in the most diseased segment of the ascending aorta (TBRmax) was measured to assess vascular inflammation. 82Rb PET studies were used to assess changes in left ventricular MFR. A total of 34 participants were enrolled in the study (11 in group 1, 13 in group 2, and 10 controls). A significant drop in the thoracic aorta uptake was observed in the biologic-treated group (ΔTBRmax: - .46 ± .55) compared to the PsO group treated with non-biologic therapy (ΔTBRmax: .23 ± .67). Those showing response to biologic agents maintained MFR compared to who showed no response. CONCLUSION: In a cohort of psoriasis patients treated with biologics, FDG uptake in the thoracic aorta decreased over the study period. Patients who demonstrated a significant anti-inflammatory response on FDG PET imaging maintained their MFR compared to non-responders.

Intense FDG Uptake in the Common Bile Duct Post-ERCP Mimics Acute Infectious Cholangitis.

In patients with obstructive pancreatitis due to choledocholithiasis, endoscopic retrograde cholangiopancreatography (ERCP) is the standard of care. ERCP-induced inflammation or infection of the common bile duct (i.e., cholangitis) is a rare complication with a high mortality rate in severe cases. We report an unusual case of incidental findings of intense FDG uptake in the common bile duct one month post-ERCP without clinical features of acute cholangitis, indicative of inflammation of CBD associated with or exaggerated by ERCP.

Foreign body-type giant cell reaction with extensive granulation tissue and intense inflammation after chemotherapy mimicking residual lymphoma on FDG PET.

Foreign body-type giant cell reaction is typically a biological and immunological reaction to the presence of foreign bodies such as catheters, parasites or biomaterials with a collection of fused macrophages (giant cell). We reported an unusual case of [18F]FDG PET findings in diffuse large B cell lymphoma in the urinary bladder following incomplete resection and chemotherapy. As the restaging [18F]FDG PET showed intense [18F]FDG uptake in the urinary bladder at the resection site concerning for recurrence, the lesion was subsequently resected and histopathology showed extensive granulation tissue with foreign body-type giant cell reaction with no suspected foreign bodies or neoplasia.

Intensity of hypermetabolic axillary lymph nodes in oncologic patients in relation to timeline following COVID-19 vaccination.

PURPOSE: First discovered in Wuhan, China in December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) is a highly contagious and deadly novel virus that quickly wreaked havoc throughout the world. As mass vaccination are now underway worldwide, clinicians have started to encounter a new clinical entity, COVID-19 vaccine-associated axillary lymphadenopathy. This presents a unique challenge to medical imagers, particularly in oncologic patients. METHODS: In this retrospective study, we assessed metabolic activity, size, and timeline of COVID-19 vaccine-associated axillary hypermetabolic lymph nodes in 202 oncologic patients post vaccination with 18-fluorodeoxyglucose positron emission tomography (18-FDG PET). RESULTS: When present, COVID-19 vaccine-associated hypermetabolic lymph nodes demonstrate a mean maximum standard uptake value (SUVmax) of 2.5 ± 0.3, and more common in younger patients. The metabolic activity is the most intense in the first two weeks post vaccination and diminishes over time. By approximately 5-6 weeks, only about half of the patients demonstrated appreciable, low grade uptake compared to background. CONCLUSION: Based on our preliminary results, we would recommend correlation with a history and time of vaccination and routine use of a pre-study patient questionnaire to guide interpretation to prevent over-diagnosis of axillary nodal metastases and/or unnecessary work-up in oncologic patients.

Anti-inflammatory effect of rosuvastatin in patients with HIV infection: An FDG-PET pilot study.

AIMS: This study aimed to evaluate markers of systemic as well as imaging markers of inflammation in the ascending aorta, bone marrow, and spleen measured by 18F-FDG PET/CT, in HIV+ patients at baseline and following therapy with rosuvastatin. METHODS AND RESULTS: Of the 35 HIV+ patients enrolled, 17 were randomized to treatment with 10 mg/day rosuvastatin and 18 to usual care for 6 months. An HIV- control cohort was selected for baseline comparison of serum inflammatory markers and monocyte markers of inflammation. 18F-FDG-PET/CT imaging of bone marrow, spleen, and thoracic aorta was performed in the HIV+ cohort at baseline and 6 months. While CD14++CD16- and CCR2 expressions were reduced, serum levels of IL-7, IL-8, and MCP-1 were elevated in the HIV+ population compared to the controls. There was a significant drop in FDG uptake in the bone marrow (TBRmax), spleen (SUVmax) and thoracic aortic (TBRmax) in the statin-treated group compared to the control group (bone marrow: - 10.3 ± 16.9% versus 5.0 ± 18.9%, p = .0262; spleen: - 9.8 ± 20.3% versus 11.3 ± 28.8%, p = .0497; thoracic aorta: - 19.1 ± 24.2% versus 4.3 ± 15.4%, p = .003). CONCLUSIONS: HIV+ patients had significantly markers of systemic inflammation including monocyte activation. Treatment with low-dose rosuvastatin in the HIV+ cohort significantly reduced bone marrow, spleen and thoracic aortic FDG uptake.

Thyroid Uptake Exceeding 100%: Causes and Prevention.

Background: Radionuclide thyroid uptake measurements reflect the metabolic activity of the thyroid gland. Thyroid uptake is measured as a percentage of radioactivity retained by the gland at a specified time versus the activity administered to the patient; thus, uptake measurements must fall between 0 and 100%. In this study we review sources of errors that can lead to uptake >100% through a case study and describe a novel quality control (QC) indicator to improve the accuracy of uptake measurements in the clinic. Methods: Probe efficiency is determined as the ratio between dose counts of the probe relative to the independent dose calibrator activity readings. The nominal probe efficiency value (M) was calculated as the mean of readings (n≥20) and variance was characterized using the standard-deviation (SD). Warning levels were set at M±1.96×SD and error levels were set to M±2.58×SD. In subsequent routine clinical use, prior to administrating a capsule, the probe efficiency is calculated and compared with the warning and error limits. We derived M for three pairs of probe and dose-calibrator devices using several doses and measured independently by several nuclear medicine technologists. Results: The recorded data indicated that nominal efficiency was statistically different between our old device and the one that replaced it (P = 0.01) but coefficient-of-variation(CV% =SD/M×100%) was not (P = 0.42) when technologists were made aware of the expected efficiency value. Using efficiency measurements of the first 20 first patients acquired on the replacement device new QC values were derived (M= 910, SD =36). In 22 patients measured at our sister site, with the same device models but without technologists being aware of QC initiative, derived QC values were (M =1025, SD =116), demonstrating a significant difference between nominal values of individual devices (p<0.001). Furthermore, variability was significantly lower (p<0.001) when QC was followed compared to when it was not applied. Conclusion: Adding the probe efficiency as a quality control indicator during thyroid uptake measurement is simple, can produce more precise clinical measurement and help mitigate operator and instrumentation errors.

The impact of measuring split kidney function on post-donation kidney function: A retrospective cohort study.

BACKGROUND: Studies have reported agreement between computed tomography (CT) and renography for the determination of split kidney function. However, their correlation with post-donation kidney function remains unclear. We compared CT measurements with renography in assessment of split kidney function (SKF) and their correlations with post-donation kidney function. METHODS: A single-centre, retrospective cohort study of 248 donors from January 1, 2009-July 31, 2019 were assessed. Pearson correlations were used to assess post-donation kidney function with renography and CT-based measurements. Furthermore, we examined high risk groups with SKF difference greater than 10% on renography and donors with post-donation eGFR less than 60 mL/min/1.73m2. RESULTS: 62% of donors were women with a mean (standard deviation) pre-donation eGFR 99 (20) and post-donation eGFR 67 (22) mL/min/1.73m2 at 31 months of follow-up. Post-donation kidney function was poorly correlated with both CT-based measurements and renography, including the subgroup of donors with post-donation eGFR less than 60 mL/min/1.73m2 (r less than 0.4 for all). There was agreement between CT-based measurements and renography for SKF determination (Bland-Altman agreement [bias, 95% limits of agreement] for renography vs: CT volume, 0.76%, -7.60-9.15%; modified ellipsoid,1.01%, -8.38-10.42%; CC dimension, 0.44%, -7.06-7.94); however, CT missed SKF greater than 10% found by renography in 20 out 26 (77%) of donors. CONCLUSIONS: In a single centre study of 248 living donors, we found no correlation between CT or renography and post-donation eGFR. Further research is needed to determine optimal ways to predict remaining kidney function after donation.

Persistent Lung Inflammation After Clinical Resolution of Community-Acquired Pneumonia as Measured by 18FDG-PET/CT Imaging.

BACKGROUND: Survivors of community-acquired pneumonia (CAP) are at increased risk of cardiovascular disease, cognitive and functional decline, and death, but the mechanisms remain unknown. RESEARCH QUESTION: Do CAP survivors have evidence of increased inflammatory activity in their lung parenchyma on 2-deoxy-2-[18F]fluoro-d-glucose (18FDG)-PET/CT imaging after clinical resolution of infection? STUDY DESIGN AND METHODS: We obtained 18FDG-PET/CT scans from 22 CAP survivors during their hospitalization with pneumonia (acute CAP) and 30 to 45 days after hospital discharge (post-CAP). In each set of scans, we assessed the lungs for foci of increased 18FDG uptake by visual interpretation and by total pulmonary glycolytic activity (tPGA), a background-corrected measure of total metabolic activity (as measured by 18FDG uptake). We also measured, post-CAP, the glycolytic activity of CAP survivor lung areas with volumes similar to the areas in 28 matched historical control subjects without pneumonia. RESULTS: Overall, 68% of CAP survivors (95% CI, 45%-85%) had distinct residual areas of increased 18FDG uptake in their post-CAP studies. tPGA decreased from 821.5 (SD, 1,140.2) in the acute CAP period to 80.0 (SD, 81.4) in the post-CAP period (P = .006). The tPGA post-CAP was significantly higher than that in lung areas of similar volume in control subjects (80.0 [SD, 81.4] vs -19.4 [SD, 5.9]; P < .001). INTERPRETATION: An important proportion of CAP survivors have persistent pulmonary foci of increased inflammatory activity beyond resolution of their infection. As inflammation contributes to cardiovascular disease, cognitive decline, functional waning, and mortality risk in the general population, this finding provides a plausible mechanism for the increased morbidity and mortality that have been observed post-CAP.

Quantitative analysis of technetium-99m-sestamibi uptake and washout in parathyroid scintigraphy supports dual mechanisms of lesion conspicuity.

PURPOSE: Proposed mechanisms of parathyroid localization in 'dual-phase' technetium-99m-sestamibi imaging include increased presence of mitochondria leading to greater uptake and slower washout compared with thyroid tissues owing to reduced expression of P-glycoprotein. Using new techniques of quantitative single-photon emission computed tomography (SPECT)/computed tomography (CT), we have measured MIBI uptake and washout to better understand factors related to conspicuity. PATIENTS AND METHODS: We retrospectively reviewed 125 consecutive patients. Early and delayed SPECT/CT images were reconstructed using a previously validated technique. Maximum standardized uptake values of parathyroid adenomas and thyroid tissue were measured, and corresponding washout rates were calculated. RESULTS: Of 53 patients with localization of parathyroid adenoma (42%), median maximum standardized uptake values were higher for parathyroid adenomas than for thyroid tissue on both early (6.43±3.78 vs. 4.43±1.93, P<0.001) and delayed (3.40±3.09 vs. 1.84±1.05, P<0.001) images, being true on a per-patient basis in 41 (77%) and 48 (91%) patients, respectively. Median washout rates were slower from parathyroid adenomas than from thyroid lobes (0.26±0.16 vs. 0.42±0.18 h, P<0.001), being true on a per-patient basis in 43 (81%) patients. Similar findings were observed in a subgroup of 37 patients with surgically-confirmed adenomas. Of the patients where initial parathyroid uptake did not exceed thyroid uptake, all 12 exhibited slower MIBI washout from the parathyroid adenomas than from the thyroid gland. The characteristics of the thyroid gland did not differ in 67 patients without parathyroid localization. CONCLUSION: Quantitative analysis of 53 patients with localization of parathyroid adenoma revealed both a generally higher initial absolute uptake and slower rate of washout of MIBI in parathyroid adenomas than in thyroid tissue. The findings may support the hypothesis that both mechanisms proposed for parathyroid conspicuity in the dual-phase examination increased mitochondrial binding and slower washout owing to reduced P-glycoprotein expression. The technique of quantitative SPECT/CT represents a powerful tool for measuring tissue uptake to elucidate the contribution of these factors to lesion conspicuity.

Residual pulmonary embolism as a predictor for recurrence after a first unprovoked episode: Results from the REVERSE cohort study.

BACKGROUND: The optimal duration of oral anticoagulant therapy after a first, unprovoked venous thromboembolism is controversial due to tightly balanced risks and benefits of indefinite anticoagulation. Risk stratification tools may assist in decision making. OBJECTIVES: We sought to determine the relationship between residual pulmonary embolism assessed by baseline ventilation-perfusion scan after completion of 5-7months of oral anticoagulant therapy and the risk of recurrent venous thromboembolism in patients with the first episode of unprovoked pulmonary embolism. METHODS: We conducted a multicentre prospective cohort study of participants with a first, unprovoked venous thromboembolism enrolled after the completion of 5-7months of oral anticoagulation therapy. The participants completed a mean 18-month follow-up. Participants with pulmonary embolism had baseline ventilation-perfusion scan before discontinuation of oral anticoagulant therapy and the percentage of vascular obstruction on baseline ventilation-perfusion scan was determined. During follow-up after discontinuation of oral anticoagulant therapy, all episodes of suspected recurrent venous thromboembolism were independently adjudicated with reference to baseline imaging. MEASUREMENTS AND MAIN RESULTS: During follow-up, 24 of 239 (10.0%) participants with an index event of isolated pulmonary embolism or pulmonary embolism associated with deep vein thrombosis and central assessment of percentage of vascular obstruction on baseline ventilation-perfusion scan had confirmed recurrent venous thromboembolism. As compared to participants with no residual pulmonary embolism on baseline ventilation-perfusion scan, the hazard ratio for recurrent venous thromboembolism was 2.0 (95% CI 0.5-7.3) for participants with percentage of vascular obstruction of 0.1%-4.9%, 2.1 (95% CI 0.5-7.8) for participants with percentage vascular obstruction of 5.0%-9.9% and 5.3 (95% CI 1.8-15.4) for participants with percentage vascular obstruction greater than or equal to 10%. CONCLUSIONS: Residual pulmonary embolism assessed by pulmonary vascular obstruction on baseline ventilation-perfusion performed after 5-7months of oral anticoagulant therapy for the first episode of unprovoked pulmonary embolism was associated with a statistically significant higher risk of subsequent recurrent venous thromboembolism. Percentage of pulmonary vascular obstruction assessment by ventilation-perfusion scans maybe a useful tool to help guide the duration of oral anticoagulant therapy after a first unprovoked pulmonary embolism. TRIAL REGISTRATION: Registered at www.clinicaltrials.gov identifier: NCT00261014.

Dual time-point quantitative SPECT-CT parathyroid imaging using a single computed tomography: feasibility and operator variability.

OBJECTIVES: Dual-phase parathyroid scan with Tc-sestamibi is a standardized imaging method for diagnosing parathyroid adenoma and hyperplasia. Conventional planar images using a gamma camera are performed routinely in early and delayed time points, followed by a single SPECT-CT. SPECT-CT on both early and delayed time points, although clinically useful, is not commonly performed to avoid extra radiation exposure from computed tomography (CT). This study explores the feasibility of co-registering early and delayed SPECT-CT from a single CT and evaluates the most effective combination of images for co-registration. PATIENTS AND METHODS: Fourteen retrospective patients with early and delayed planar and SPECT-CT images were recruited for this validation study. Results from contemporaneous early and delayed SPECT-CT, with hardware matched registration, are considered the gold standard. Noncontemporaneous early SPECT with delayed CT and vice versa were also processed with manual alignment by an experienced and a novice operator three times each to evaluate interoperator and intraoperator variability. Maximum standardized uptake values (SUVmax) of the thyroid lobes and parathyroid adenomas were measured, and the results in terms of accuracy and precision from noncontemporaneous SPECT-CT acquisitions were evaluated. RESULTS: Good image quality from co-registered SPECT-CT acquired at different time points with the results showed no bias (P>0.5). The co-registration of early SPECT and delayed CT showed higher precision than the alternative combination. Overall, the experienced operator achieved better precision and intraoperator variability than the novice operator (reproducibility coefficient=33% SUV vs. reproducibility coefficient=54% SUV, P<0.001). CONCLUSION: Quantitative SUV measurement from early and delayed parathyroid SPECT-CT imaging is feasible, with the best result achieved by experienced operators using delayed CT in manual registration.

Osteoblastic Metastases Mimickers on Contrast Enhanced CT.

Secondary osseous involvement in lymphoma is more common compared to primary bone lymphoma. The finding of osseous lesion can be incidentally discovered during the course of the disease. However, osseous metastases are infrequently silent. Detection of osseous metastases is crucial for accurate staging and optimal treatment planning of lymphoma. The aim of imaging is to identify the presence and extent of osseous disease and to assess for possible complications such as pathological fracture of the load-bearing bones and cord compression if the lesion is spinal. We are presenting two patients with treated lymphoma who were in complete remission. On routine follow-up contrast enhanced CT, there were new osteoblastic lesions in the spine worrisome for metastases. Additional studies were performed for further evaluation of both of them which did not demonstrate any corresponding suspicious osseous lesion. The patients have a prior history of chronic venous occlusive thrombosis that resulted in collaterals formation. Contrast enhancement of the vertebral body marrow secondary to collaterals formation and venous flow through the vertebral venous plexus can mimic the appearance of spinal osteoblastic metastases.

The Imaging Findings of Erdheim-Chester Disease: A Multimodality Approach to Diagnosis and Staging.

Erdheim-Chester disease (ECD) is a rare, non-Langerhans histiocytic disorder. The most common manifestations consist of polyostotic sclerotic lesions with the majority of cases also demonstrating soft tissue involvement of the sinuses, retroperitoneum, large vessels, heart, lungs, and central nervous system. Nuclear medicine can play an important role in assessing the extent of the disease with bone scintigraphy and fluorodeoxyglucose (FDG)-positron emission tomography (PET). We present the case of a middle-aged female who initially presented with tooth pain. She subsequently underwent imaging including plain film, bone scan, computed tomography (CT), magnetic resonance imaging (MRI), and FDG-PET/CT, which showed characteristic bony involvement. Biopsy results confirmed the diagnosis of ECD.

Posterior bladder layering of excreted 18F-FDG on PET/CT.

PURPOSE: This study was carried out to determine the frequency, characteristics and possible causes and clinical significance of occasionally observed posterior layering of excreted 2-deoxy-2-[F]fluoro-D-glucose (F-FDG) in the bladder. PROCEDURES: A review of 567 consecutive patients referred for positron emission tomography/computerized tomography studies was performed. Urinary bladder size was measured in patients with and without layering. Urine samples from two patients with layering were imaged ex vivo. RESULTS: Twenty-four of 567 studies (4%) showed F-FDG posterior bladder layering. Mean volume+/-SD of the bladder was 175+/-161 ml in patients with layering and 93+/-83 ml in patients without layering. Urine samples collected from two randomly chosen patients with layering in vivo failed to show layering ex vivo. CONCLUSION: Posterior F-FDG layering occurs in 4% of positron emission tomography/computerized tomography cases and highly correlates with bladder volume. The mechanism is hypothesized to be because of slow F-FDG excretion in patients with a distended urinary bladder resulting in delayed mixing with urine, but needs to be further investigated with a more comprehensive study.

Spectrum of FDG PET/CT findings in Burkitt lymphoma.

PURPOSE: F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) is known to be a useful diagnostic tool for staging, restaging, and monitoring therapy for lymphoma. The purpose of this retrospective study is to present a spectrum of FDG PET findings at initial presentation of Burkitt lymphoma and subsequent findings after therapy. METHOD AND MATERIALS: We retrospectively reviewed 48 patients with Burkitt lymphoma referred for a total of 160 FDG PET/computed tomography (CT) scans at our institution. We characterized the disease distribution of Burkitt lymphoma in all patients and measured representative FDG activity from initial staging scans. Therapeutic response and disease remission were assessed in patients with PET/CT and clinical follow-up studies. RESULTS: Of the 48 patients diagnosed with Burkitt lymphoma, 25 patients had FDG PET/CT scans for initial staging. All untreated lesions of Burkitt lymphoma were highly FDG avid. The mean maximum standardized uptake value of 54 representative lesions is 16.5 (range: 6-54). Twelve patients were immune compromised. The majority of patients had disease localized to the abdomen and the pelvis. Extranodal involvement was identified in more than half of the patients studied. CONCLUSION: The American (or sporadic) form of Burkitt lymphoma presented with intense hypermetabolic lesions when untreated. The information is useful in evaluating post-treatment studies in the absence of a pretreatment scan.