Routine Positron Emission Tomography Research Articles

Considerations for multidisciplinary management of synchronous primary breast cancer and primary lung cancer - Analysis of thirty-one patients.

The simultaneous (synchronous) presence of primary breast cancer and primary lung cancer diagnosed in a single individual is not an uncommon phenomenon. However, reference data for treatment strategy is scarce and "chaotic". In the present study we discuss the management strategy for this group of patients. We retrospectively reviewed patients in the primary breast cancer database of the Breast Center and the primary lung cancer database of the Thoracic Surgery Department I of Peking University Cancer Hospital. Patients with synchronous primary breast cancer and primary lung cancer who underwent surgery between December 2010 and December 2023 were included in the study. The sequence of outpatient visits, recommendations of multidisciplinary teams, perioperative treatment, and surgical procedures were reviewed. Meanwhile, survival analysis based on propensity score matching with 1:1 ratio was performed between the 31 patients and those with lung cancer only during the same period. A total of 31 patients with synchronous primary breast cancer and primary lung cancer were identified; all of the patients were women. The average age was 61 years. A total of 24 of the patients had visited the breast center first, and routine chest computed tomography (CT) showed evidence of primary lung cancer. The other seven patients had visited the thoracic surgery clinic first, and routine positron emission tomography (PET)-CT revealed the coexistence of primary breast cancer. All the patients had multidisciplinary team consultations, after which 20 patients were recommended to have preoperative treatment for breast cancer, two patients were recommended to have preoperative treatment for lung cancer, and nine patients were recommended to undergo surgery directly. After surgery, 23 patients received postoperative adjuvant treatment for breast cancer, and no patients needed postoperative adjuvant treatment for lung cancer. Survival analysis showed that there was no significant difference between the 31 patients and those with lung cancer only. Routine chest CT is needed for breast cancer patients before surgery, and PET-CT is required for the accurate staging of lung cancer patients. A multidisciplinary expert team should manage synchronous primary breast cancer and primary lung cancer. Emphasis should be placed on patients who need preoperative treatment before surgery. Particularly, for patients who need preoperative chemotherapy, a regimen should be chosen that balances the treatment of lung cancer and breast cancer.

Sensitive Positron Emission Tomography Imaging of PD-L1 Expression in Human Breast and Lung Carcinoma Xenografts Using the Radiometalated Peptide Ga-68-TRAP-WL12.

Noninvasive imaging of the immune checkpoint protein programmed death ligand 1 (PD-L1; synonyms: CD274, B7-H1) holds great promise to improve patient selection and, thus, response rates for immune checkpoint therapy (ICT) with monoclonal antibodies targeting the PD1/PD-L1 axis. The PD-L1 specific peptide WL12 (cyclo(AcY-(NMe)A-N-P-H-L-Hyp-W-S-W(Me)-(NMe)Nle-(NMe)Nle-O-C)-G-NH2) was functionalized with the Gallium-68 chelator TRAP by means of click chemistry (CuAAC). The resulting conjugate TRAP-WL12 was labeled with Gallium-68 within 16 min, with approximately 90% radiochemical yield and 99% radiochemical purity, affording Ga-68-TRAP-WL12 with molar activities typically exceeding 100 MBq/nmol. This radiotracer was characterized by positron emission tomography (PET) imaging and ex vivo biodistribution in murine xenografts of nontransfected PD-L1 expressing tumor cell lines, MDA-MB-231 (human breast carcinoma), and H2009 (human lung adenocarcinoma). It showed a favorable biodistribution profile with rapid renal clearance and low background (tumor-to-blood ratio = 26.6, 3 h p.i.). Conjugation of the Ga-68-TRAP moiety to WL12 successfully mitigated the nonspecific uptake of this peptide in organs, particularly the liver. This was demonstrated by comparing Ga-68-TRAP-WL12 with the archetypical Ga-68-DOTA-WL12, for which tumor-to-liver ratios of 1.4 and 0.5, respectively, were found. Although immunohistochemistry (IHC) revealed a low PD-L1 expression in MDA-MB-213 and H2009 xenografts that corresponds well to the clinical situation, PET showed high tumor uptakes (6.6 and 7.3% injected activity per gram of tissue (iA/g), respectively) for Ga-68-TRAP-WL12. Thus, this tracer has the potential for routine clinical PD-L1 PET imaging because it detects even very low PD-L1 expression densities with high sensitivity and may open an avenue to replace PD-L1 IHC of biopsies as the standard means to select potential responders for ICT.

Fully automated production of [11C]PiB for clinical use on Trasis-AllinOne synthesizer module

Pittsburgh compound B ([11C]PiB) was the first broadly applied radiotracer with specificity for amyloid-β (Aβ) peptide aggregates in the brain and has since been established as the gold standard for positron emission tomography (PET) employed for clinical in vivo imaging of Aβ plaques, used for imaging applications of Alzheimer's disease (AD), related dementia, and other tauopathies. The use of [11C]PiB for routine PET studies is dependent on the production capabilities of each radiochemistry laboratory, subsequently a continuous effort is made to develop suitable and sustainable methods on a variety of auto synthesis platforms.Here we report a fully automated, multi-step radio synthesis, purification, and reformulation of [11C]PiB for PET imaging using the Trasis AllinOne synthesis unit, a commonly used commercial radiochemistry module. We performed three validation runs to evaluate the reproducibility and to verify that the acceptable criteria were met for the release of clinical-grade [11C]PiB using a Trasis AllinOne auto radiosynthesis unit. Solid phase supported radiolabeling was performed through the capture of precursor (6-OH-BTA-0) on a C18 solid phase extraction (SPE) cartridge and subsequent flushing of gaseous [11C]Methyl triflate(MeOTf) through the Sep-Pak for carbon-11 (11C) N-methylation. Starting with 92.5 GBq [11C]CO2, [11C]PiB synthesis was completed in approximately 25 min after cyclotron end of bombardment with an injectable dose >7.0 GBq at end of the synthesis. The radiopharmaceutical product met all quality control criteria and specifications for use in human studies.

Deep learning based registration for head motion correction in positron emission tomography as a strategy for improved image quantification

Objectives: Positron emission tomography (PET) is affected by various kinds of patient movement during a scan. Frame-by-frame image registration is one of the most practiced motion correction techniques. In recent years, deep learning has shown a remarkable ability to quickly and accurately register images once trained. This paper studies the feasibility of using a deep learning framework to correct 3D positron emission tomography image volumes for head motion in routine positron emission tomography imaging to improve quantification in motion impacted data.Materials and Methods: A neural network was trained with 3D positron emission tomography image volumes in an unsupervised manner to predict transformation parameters required to perform image registration. A multi-step convolutional neural network (CNN) was combined with a spatial transform layer. Pairs of target and source images were used as input to the network. To prepare the training dataset, a previously published TOF-PEPT algorithm was applied to automatically detect static frames where the patient remained in a relatively steady position and transitional frames where they underwent abrupt motion. A single image volume was reconstructed for each static frame. The image reconstructed from the first static frame served as the target image with images from subsequent static frames being used as source images. The trained neural network predicted transformation parameters that could be used to perform frame-by-frame image-based motion correction but also enabled raw listmode positron emission tomography data correction where individual line-of-responses were repositioned. Line profiles and ROIs were drawn across the reconstructed image volumes to compare performance and quantitative results between standard registration tools and the deep learning technique. Corrected volumes were further compared to motion free images quantitatively using Dice indices.Results: In total, one hundred 3D positron emission tomography image volumes were used to train the network. Cross-validation was carried out using a 4:1 ratio for the training and test data. A conventional algorithm for affine registration from the Advanced Normalization Tools (ANTs) software package served as a baseline. To evaluate the correction performance, the mean Dice index and standardized uptake value (SUV) were used. Application of the algorithm to clinical data showed good performance with respect to registration accuracy as well as processing time. The neural network yielded a mean Dice index of ∼0.87 which was similar to the advanced Normalization Tools algorithm and did so ∼3x faster using a multi-core CPU and ∼20x faster with a GPU. Standardized uptake value analysis showed that quantitative results were 30%–60% higher in the motion-corrected images, and the neural network performed better than or close to the advanced Normalization Tools.Conclusion: The aim of this work was to study the quantitative impact of using a data-driven deep learning motion correction technique for positron emission tomography data and assess its performance. The results showed the technique is capable of producing high quality registrations that compensate for patient motion that occurs during a scan and improve quantitative accuracy.

An unusual paraesophageal and diaphragmatic SDHA-deficient gastrointestinal stromal tumor (GIST) metastases case report.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and have diverse tumor biology. Succinate dehydrogenase (SDH)-deficient GIST, comprise less than 10% of all GIST, with mutational loss of the catalytic SDHA subunit being the most common subtype. Contrary to typical GISTs harboring inactivating mutations in KIT/PDGFRA, SDH-deficient GIST has varying biology and behavior, occurring at a younger age, often metastatic on presentation and frequently refractory to conventional tyrosine kinase inhibitors (TKI). Liver and peritoneum are their most common sites of metastases, and extra-abdominal spread to the diaphragm or mediastinum has not been previously described. Herein, we present a case of a 44-year-old female patient with a history of SDHA-deficient GISTs with multiple previous metastasectomies who presented with recurrence to the paraesophageal region and diaphragm which was identified upon routine positron emission tomography (PET) surveillance. Patient subsequently underwent a robotic assisted metastasectomy using a thoracic approach. Follow up was obtained 2 months following procedure and there was no evidence of recurrence. SDHA-deficient GISTs have unique tumor biology and management of metastatic lesions remains an area of debate and discovery. Overall, this report highlights the need for comprehensive knowledge of the disease, a skilled surgical team, and multi-disciplinary involvement in order to optimize care and ensure favorable outcomes in this patient population.

Estimating Tumor Vascular Permeability of Nanoparticles Using an Accessible Diffusive Flux Model.

Understanding the complex interplay of factors affecting nanoparticle accumulation in solid tumors is a challenge that must be surmounted to develop effective cancer nanomedicine. Among other unique microenvironment properties, tumor vascular permeability is an important feature of leaky tumor vessels which enables nanoparticles to extravasate. However, permeability has thus far been measured by intravital microscopy on optical window tumors, which has many limitations of its own. Additionally, mathematical models of particle tumor transport are often too complicated to be accessible to most researchers. Here, we present a more simplified and accessible mathematical model based on diffusive flux, which uses particle tumor accumulation and plasma pharmacokinetics to yield effective permeability, Peff. This model, called diffusive flux modeling (DFM), allows effects from multiple parameters to be decoupled and is also the first demonstration, to the best our knowledge, of extracting Peff values from bulk biodistribution results (e.g., routine positron emission tomography studies). The DFM equation was used to explain in vivo results of sub-20 nm nanocarriers called three-helix-micelles (3HM), particularly 3HM's selective accumulation in different tumor models. When DFM was applied to multiple published biodistribution data, a semiquantitative comparison of various tumor models, particle size, and active targeting strategies could be made. The analysis clearly pointed out the importance of balancing multiple characteristics of nanoparticles to ensure successful treatment outcome and highlights the usefulness of this simple model for initial particle design, selection, and subsequent optimization.

Risk factors of malignant fluorodeoxyglucose-avid lymph node on preablation positron emission tomography in patients with papillary thyroid cancer undergoing radioiodine ablation therapy.

F-18 fluorodeoxyglucose (FDG)-avid metastatic lesions are associated with a poor response to radioiodine ablation therapy (RIT) in papillary thyroid cancer (PTC). This study evaluated the significance of preablative FDG positron emission tomography (PET) for the assessment of risk factors and frequency of malignant FDG-avid lymph nodes in patients with PTC undergoing RIT.The study included 339 consecutive patients (mean age 46.3 ± 12.5 y; 260 females) with PTC referred for the first RIT and who underwent routine preablative FDG PET between April 2011 and February 2013. FDG-avid lymph nodes (FALNs) were identified using retrospective image reviews. The frequency of malignant FALN (mFALN), its contribution to persistent or recurrent PTC, and its risk factors were analyzed.Among the patients, 112 had FALNs (33.0%): 11 mFALNs (3.2%) and 101 benign FALNs (bFALNs, 29.8%). mFALN contributed to 55% of persistent or recurrent PTC after RIT, which was observed in 20 of 339 patients (5.9%) during the post-RIT follow-up. Among preoperative risk factors, suspicious extrathyroidal extension and lateral neck lymph node metastasis on imaging studies were associated with mFALN. Among postoperative risk factors, T3/T4 and N1b stages, higher stimulated thyroglobulin, and higher numbers of metastatic lymph nodes and dissected lymph nodes, were associated with mFALN.mFALNs were observed in a small number of patients with PTC undergoing RIT, but it contributed 55% of total recurrent or persistent disease. Increased frequency of mFALNs is associated with more advanced PTC. Preablative FDG PET has value in evaluation of patients with RIT-resistant lesions and may help determine further treatment strategies.

Utilization of imaging modalities in the staging of newly diagnosed rectal cancer: A survey of U.S. radiation oncologists.

564 Background: Accurate staging is crucial for management of patients (pts) with newly diagnosed rectal cancer. Endorectal ultrasound (EUS) has been a commonly used imaging modality for almost two decades, with magnetic resonance imaging (MRI) now preferred by national guidelines. Routine positron emission tomography (PET) is not recommended for initial staging. The current utilization of imaging modalities by radiation oncologists (ROs) in staging newly diagnosed rectal cancer pts in the United States is unknown. Methods: We conducted an anonymous IRB-approved online survey of practicing U.S. ROs. Respondent characteristics were tested for association with self-assessed utilization of imaging modalities using Chi-squared test. Staging 75% of more rectal cancer pts with a given modality was defined as high utilization. Results: We received 220 responses from practicing U.S. ROs. Among the responders, 85 are academically affiliated and the majority specialize in treating GI malignancies, with 98 seeing more than 10 rectal cancer pts annually. Most respondents utilize all three imaging modalities for rectal cancer staging - EUS, MRI and PET/CT. Fifty two percent and 38% of respondents are high utilizers of EUS and MRI, respectively. Nearly half (47%) of respondents are high PET utilizers. High utilization of PET was associated with practice in a private setting (p < 0.05) and being within 10 years from residency training completion (p < 0.05). Conclusions: Our analysis reveals a wide discordance between national guidelines and the practice patterns among U.S. ROs, with underutilization of MRI and overutilization of PET/CT. Substantial cost savings could be realized by following national guidelines recommendations to omit the routine use of PET/CT in the initial evaluation of pts with rectal cancer.

A Unique Case of Rituximab-Induced Crohnʼs Disease: A Case Report and Review of Literature

Rituximab is a humanized monoclonal antibody against CD20 which is a mainstay of therapy for a wide variety of B cell malignancies. There are only two reported cases of Crohn's disease following treatment with Rituximab in the literature. We present a very unique case of a 58 year old female who was treated with Rituximab, Cyclophosphamide, Doxorubicin, Vincristine and Prednisolone (R-CHOP) regimen for initial diagnosis of follicular cell lymphoma of the tonsils. She was treated with prolonged maintenance Rituximab treatment for a recurrence of the lymphoma two years later and the treatment was continued for two and a half years. Three years later she was noted to have increased activity in the terminal ilium and mesenteric lymph nodes on a routine positron emission tomography (PET) scan. At that time, she was asymptomatic and refused any further workup or treatment. Another PET scan done two years later showed enlarged mesenteric lymph nodes with increased activity in the terminal ileum and the spleen. A colonoscopy performed at that time revealed inflammation with extensive ulceration in the terminal ileum. Biopsy demonstrated severely active chronic nonspecific ileitis with ulceration and a small granulomatous lesion. She was then re-treated again with 4 cycles of rituximab for a presumed recurrence. Two months after the treatment, she developed severe abdominal pain leading to an emergency room visit. A computerized tomography (CT) scan showed thickening in the distal descending colon as well as the entire sigmoid colon with surrounding fat stranding. She was treated with oral ciprofloxacin and metronidazole for 10 days with improvement in the symptoms. In a follow-up PET scan done a month later, the mesenteric adenopathy resolved but the activity in the terminal ileum was unchanged and there was new activity in the sigmoid colon. The patient refused further endoscopic examination, however the PET scan findings of worsening of the bowel inflammation and resolution of the adenopathy strongly suggests Rituximab induced Crohn's disease. This case portrays the importance of being alert to the possibility of Crohn's disease occurring as complication of Rituximab treatment. This case is unique as the Crohn's disease occurred almost three years after the initial Rituximab treatment. Management of Crohn's disease in patients with a history of lymphoma can be challenging due to the risk of lymphoma from Anti-TNF and immunomodulatory treatments.Figure: PET Scan showing increased uptake in the mesenteric lymph nodes and terminal ileum.Figure: Colonoscopy image of the terminal ileum.

Status of F-18 fluorodeoxyglucose uptake in normal and hibernating myocardium after glucose and insulin loading

ObjectiveF-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) has been increasingly used in myocardial viability imaging. In routine PET viability studies, oral glucose and intravenous insulin loading is commonly utilized. In an optimal study, glucose and insulin loading is expected to cause FDG uptake both in hibernating and normal myocardium. However, in routine studies it is not uncommon to see absent or reduced FDG uptake in normal myocardium. In this retrospective study we further analyzed our PET viability images to evaluate FDG uptake status in myocardium under the oral glucose and intravenous insulin loading protocol that we use in our hospital. MethodsPatients who had both myocardial perfusion single photon emission computed tomography (SPECT) and FDG PET cardiac viability studies were selected for analysis. FDG uptake status in normal and abnormal myocardial segments on perfusion SPECT was evaluated. Based on SPECT and PET findings, patients were divided into two main groups and four subgroups. Group 1 included PET viable studies and Group 2 included PET-nonviable studies. Subgroups based on FDG uptake in normal myocardium were 1a and 2a (normal uptake) and 1b and 2b (absent or significantly reduced uptake). ResultsSeventy-one patients met the inclusion criteria. Forty-two patients were PET-viable and 29 were PET-nonviable. In 33 of 71 patients (46.4%) there was absent or significantly reduced FDG uptake in one or more normal myocardial segments, which was identified more in PET-viable than PET-nonviable patients (59.5% vs. 27.5%, p=0.008). This finding was also more frequent in diabetic than nondiabetic patients (53% vs. 31.8%), but the difference was not significant (p=0.160). ConclusionsIn nearly half of our patients, one or more normal myocardial segments showed absent or significantly reduced FDG uptake. This finding, particularly if it is diffuse, could be from suboptimal study, inadequacy of current glucose and insulin loading protocols, or various other patient-related causes affecting FDG uptake both in the normal and hibernating myocardium. In cases with significantly reduced FDG uptake in normal myocardium, PET images should be interpreted cautiously to prevent false-negative results for viability.

Localized peritoneal carcinomatosis mimicking an irreducible left inguinal hernia

Perforated colonic cancers are not rare and leave patients at risk of developing peritoneal carcinomatosis. We present a 68-year-old male patient with a perforated transverse colonic tumour who underwent emergency extended right hemicolectomy. He made an uneventful postoperative recovery, and received adjuvant chemotherapy. Unfortunately, a routine positron emission tomography-computed tomography scan 16 months later demonstrated an fluorodeoxyglucose-avid nodule in the left scrotum associated with an irreducible left inguinal hernia that contained sigmoid colon. At laparotomy, the discovery of isolated peritoneal recurrence in the hernia sac was unexpected, given the absence of local recurrence in the region of the original transverse colon cancer perforation. The etiology therefore remains uncertain, but one may speculate that cell implantation occurred within the hernia sac at the initial emergency laparotomy.

Hodgkin lymphoma: an Australian experience of ABVD chemotherapy in the modern era.

Approximately 560 new cases of Hodgkin lymphoma (HL) are diagnosed annually in Australia. Standard first-line therapy is ABVD (doxorubicin, bleomycin, vinblastine, dacarbazine). It is unknown how survival outcomes in patients receiving ABVD in current clinical practice, with routine positron emission tomography (PET) imaging and modern supportive measures, compare with results from published trials. This is a retrospective multi-centre study of patients with previously untreated HL between November 1999 and December 2014 receiving ABVD induction. Baseline characteristics, treatment details, toxicity and outcome data were collected from hospital records. The primary endpoint was overall survival (OS). Secondary endpoints included overall response rate (ORR), progression-free survival (PFS), response to treatment and toxicity. One hundred and eighty-nine eligible patients were identified. Median age was 32 years (range 17-79). Nodular-sclerosing HL was the most common subtype (78 %), 44 % had B symptoms and 11 % had marrow involvement. Median number of cycles of ABVD administered was 6 (range 3-8). Eighteen patients (11 %) had dose delay, 21 (13 %) had dose reductions and 11 (8 %) had both. The ORR, defined predominantly by PET scan, was 96 % (CR 89 %). Five-year OS and PFS were 93 and 84 %, respectively in early disease (stage I-IIA) and 89 and 63 % in advanced disease (stage IIB, III and IV). No poor prognostic factors were identified on multivariate testing. The most common grade 3/4 toxicity was neutropenia (53 %). Our study confirms the excellent prognosis and manageable toxicity in HL patients receiving ABVD in phase III studies are reflected in patients treated in routine clinical practice in the modern era.

68Ga-Based radiopharmaceuticals: production and application relationship.

The contribution of 68Ga to the promotion and expansion of clinical research and routine positron emission tomography (PET) for earlier better diagnostics and individualized medicine is considerable. The potential applications of 68Ga-comprising imaging agents include targeted, pre-targeted and non-targeted imaging. This review discusses the key aspects of the production of 68Ga and 68Ga-based radiopharmaceuticals in the light of the impact of regulatory requirements and endpoint pre-clinical and clinical applications.

(106) - Rubidium Positron Emission Tomography and Coronary Flow Reserve Predicts Graft Function After Heart Transplant

PurposeCardiac allograft vasculopathy (CAV) is a major factor limiting survival after heart transplant. CAV may present as small vessel or microvascular disease, which is correlated with reduced coronary flow reserve (CFR). CFR is commonly performed through intracoronary flow wire. Recently, rubidium positron emission tomography (PET) scanning has become a reliable test to demonstrate CFR. We reviewed patients with low CFR (CFR<2) and assessed them for cardiac dysfunction as defined by decreased left ventricular ejection fraction (LVEF), increased left ventricular end diastolic volume index (LVEDVI) and left ventricular enlargement.MethodsWe assessed 36 patients transplanted between 1994 and 2013 and who underwent routine rubidium PET scanning between 2011 and 2014 at their annual visit. Patients with established coronary disease were excluded. CFR was determined by rubidium PET scanning. Additional concomitant information of LVEF at rest and post stress, LVEDVI at rest and post-stress, and left ventricular enlargement was recorded.Results9 patients had a low CFR. The low CFR group had significantly decreased LVEF post-stress and a trend towards decreased LVEF at rest. The low CFR group also had significantly higher LVEDVI at rest and post-stress. A significantly larger percentage of patients had left ventricular enlargement in the low CFR group (see table).ConclusionLow CFR is associated with cardiac dysfunction which may be due to small vessel coronary disease in the absence of epicardial CAV. Rubidium PET may have a role in determining small vessel disease in heart transplant patients.Tabled 1EndpointsCFR < 2.00 (n=9)CFR > 2.00 (n=27)P-ValueAverage LVEF Rest48.7 ± 23.159.7 ± 11.90.070Average LVEF Post Stress51.3 ± 24.064.0 ± 11.90.042Average EDVI Rest69.9 ± 46.646.6 ± 16.20.030Average EDVI Post Stress74.6 ± 55.150.4 ± 15.80.044% LV Enlargement44.40%7.40%0.025 Open table in a new tab PurposeCardiac allograft vasculopathy (CAV) is a major factor limiting survival after heart transplant. CAV may present as small vessel or microvascular disease, which is correlated with reduced coronary flow reserve (CFR). CFR is commonly performed through intracoronary flow wire. Recently, rubidium positron emission tomography (PET) scanning has become a reliable test to demonstrate CFR. We reviewed patients with low CFR (CFR<2) and assessed them for cardiac dysfunction as defined by decreased left ventricular ejection fraction (LVEF), increased left ventricular end diastolic volume index (LVEDVI) and left ventricular enlargement. Cardiac allograft vasculopathy (CAV) is a major factor limiting survival after heart transplant. CAV may present as small vessel or microvascular disease, which is correlated with reduced coronary flow reserve (CFR). CFR is commonly performed through intracoronary flow wire. Recently, rubidium positron emission tomography (PET) scanning has become a reliable test to demonstrate CFR. We reviewed patients with low CFR (CFR<2) and assessed them for cardiac dysfunction as defined by decreased left ventricular ejection fraction (LVEF), increased left ventricular end diastolic volume index (LVEDVI) and left ventricular enlargement. MethodsWe assessed 36 patients transplanted between 1994 and 2013 and who underwent routine rubidium PET scanning between 2011 and 2014 at their annual visit. Patients with established coronary disease were excluded. CFR was determined by rubidium PET scanning. Additional concomitant information of LVEF at rest and post stress, LVEDVI at rest and post-stress, and left ventricular enlargement was recorded. We assessed 36 patients transplanted between 1994 and 2013 and who underwent routine rubidium PET scanning between 2011 and 2014 at their annual visit. Patients with established coronary disease were excluded. CFR was determined by rubidium PET scanning. Additional concomitant information of LVEF at rest and post stress, LVEDVI at rest and post-stress, and left ventricular enlargement was recorded. Results9 patients had a low CFR. The low CFR group had significantly decreased LVEF post-stress and a trend towards decreased LVEF at rest. The low CFR group also had significantly higher LVEDVI at rest and post-stress. A significantly larger percentage of patients had left ventricular enlargement in the low CFR group (see table). 9 patients had a low CFR. The low CFR group had significantly decreased LVEF post-stress and a trend towards decreased LVEF at rest. The low CFR group also had significantly higher LVEDVI at rest and post-stress. A significantly larger percentage of patients had left ventricular enlargement in the low CFR group (see table). ConclusionLow CFR is associated with cardiac dysfunction which may be due to small vessel coronary disease in the absence of epicardial CAV. Rubidium PET may have a role in determining small vessel disease in heart transplant patients.Tabled 1EndpointsCFR < 2.00 (n=9)CFR > 2.00 (n=27)P-ValueAverage LVEF Rest48.7 ± 23.159.7 ± 11.90.070Average LVEF Post Stress51.3 ± 24.064.0 ± 11.90.042Average EDVI Rest69.9 ± 46.646.6 ± 16.20.030Average EDVI Post Stress74.6 ± 55.150.4 ± 15.80.044% LV Enlargement44.40%7.40%0.025 Open table in a new tab Low CFR is associated with cardiac dysfunction which may be due to small vessel coronary disease in the absence of epicardial CAV. Rubidium PET may have a role in determining small vessel disease in heart transplant patients.

(105) - Influence of Liver Dysfunction in Patients Undergoing Heart Transplantation With Left Ventricular Assist Device Explantation: Comparative Analysis Using the MELD Excluding INR (MELD-XI) Scoring System

Purpose: Cardiac allograft vasculopathy (CAV) is a major factor limiting survival after heart transplant. CAV may present as small vessel or microvascular disease, which is correlated with reduced coronary flow reserve (CFR). CFR is commonly performed through intracoronary flow wire. Recently, rubidium positron emission tomography (PET) scanning has become a reliable test to demonstrate CFR. We reviewed patients with low CFR (CFR< 2) and assessed them for cardiac dysfunction as defined by decreased left ventricular ejection fraction (LVEF), increased left ventricular end diastolic volume index (LVEDVI) and left ventricular enlargement. Methods: We assessed 36 patients transplanted between 1994 and 2013 and who underwent routine rubidium PET scanning between 2011 and 2014 at their annual visit. Patients with established coronary disease were excluded. CFR was determined by rubidium PET scanning. Additional concomitant information of LVEF at rest and post stress, LVEDVI at rest and post-stress, and left ventricular enlargement was recorded. Results: 9 patients had a low CFR. The low CFR group had significantly decreased LVEF post-stress and a trend towards decreased LVEF at rest. The low CFR group also had significantly higher LVEDVI at rest and post-stress. A significantly larger percentage of patients had left ventricular enlargement in the low CFR group (see table). Conclusion: Low CFR is associated with cardiac dysfunction which may be due to small vessel coronary disease in the absence of epicardial CAV. Rubidium PET may have a role in determining small vessel disease in heart transplant patients.

The role of 18F fluorodeoxyglucose positron emission tomography (18F-FDG-PET) in children with rheumatic carditis and chronic rheumatic heart disease.

We report the use of positron emission tomography (PET) using 18F-FDG for the diagnosis of carditis in children with rheumatic heart disease (RHD). Thirty-six children aged 6-17 years (seventeen males and nineteen females) with isolated rheumatic significant mitral regurgitation (MR) underwent FDG-PET scanning of the heart after fasting for 6 h within a period of 2 years. They were divided into two groups based on Jones criteria - acute rheumatic carditis and chronic RHD. Age- and gender-matched twelve children who underwent whole body ¹⁸F-FDG-PET scan for routine PET scan for oncological evaluation was taken as controls. Nineteen patients had active carditis and 17 were chronic RHD cases. All 12 controls and all 17 cases with chronic RHD with MR showed diffuse uptake pattern. Of the 19 active cases, 14 showed ¹⁸F-FDG uptake in the myocardium, 5 did not show any uptake. Thus the finding of no uptake pattern on ¹⁸F-FDG-PET scan had a sensitivity of 26% but positive predictive value of 100% for acute carditis cases. This study describes the ¹⁸F-FDG-PET uptake pattern in children with RHD and in 12 age-matched control subjects in the fasting state. Those with chronic RHD with MR showed diffuse myocardial uptake pattern similar to that of the control group. Patients with active carditis showed mixed results; the majority showed diffuse uptake pattern. In view of its poor sensitivity, ¹⁸F-FDG-PET is not recommended as a routine imaging modality for the diagnosis of rheumatic carditis.

A Potential Role of 68Ga-DOTATOC PET in Modifying Eligibility to Surgery in Patients with Recurrent Meningioma

Patients with meningioma usually undergo surgery with curative intent, based on conventional imaging techniques such as computer tomography and magnetic resonance imaging. However, unidentified tumor lesions at the time of surgery can render the surgery non-curative. In the last decade, positron emission tomography (PET) with somatostatin receptor ligand DOTA-D-Phy1 -Tyr3 -octreotide labeled with gallium-68 (68Ga-DOTATOC) has increasingly become an important tool in the management of meningiomas compared to conventional imaging. However, its indications are not well defined. We present a case of a 60-year old woman who presented with a recurrence of an anaplastic meningioma in the right occipital region, 29 months after the primary excision of an initial diagnosed atypical meningioma. Despite two subsequent surgical excisions and two courses of stereotactic radiation treatment over a period of 42 months, the tumor continued to recur at different sites. A PET scan performed with the tracer 68Ga-DOTATOC later revealed additionally small positive lesions, suggesting a meningioma composed of multiple foci. As meningioma recurrences, particularly with multiple foci, have a significant impact on determining treatment for the individual patient, a routine 68Ga-DOTATOC PET could help avoid non-curative surgery by identifying patients with multifocal disease.

Factor structure of regional cerebral blood flow and glucose metabolism rate as a tool to study the default mode of the brain

The functional connectivity of anatomical and functional brain structures in the state of operational rest was assessed on the basis of positron emission tomography (PET) data to study the so-called default mode of the brain, i.e., the brain’s spontaneous activity at rest. It is concluded that the possibility of identifying neuroanatomical systems of the default mode (default mode network) in routine clinical PET studies of the cerebral blood flow and glucose metabolism is important for studying the functional organization of the brain in the normal state and its rearrangements in pathologies.

Assessment of a protocol for routine simultaneous myocardial blood flow measurement and standard myocardial perfusion imaging with rubidium-82 on a high count rate positron emission tomography system

High count rate positron emission tomography (PET) systems offer the potential for accurate myocardial blood flow (MBF) quantification during first-pass dynamic imaging in conjunction with standard rubidium-82 (Rb-82) PET myocardial perfusion imaging (MPI). We investigate the feasibility of this using a Siemens Biograph mCT. Current routine clinical PET MPI is performed with 1480 MBq (40 mCi) Rb-82. Dynamic first-pass images from 217 consecutive patients were reviewed for evidence of detector saturation, indicating that count rate limits had been exceeded. Phantom acquisitions in the presence of high count rates were performed to assess the effect of detector saturation on quantitative accuracy. Accurate MBF quantification and perfusion imaging using current protocols was successful in 85% of clinical cases. Detector block saturation was observed in 15% of cases, and phantom acquisitions indicate that saturation may have an adverse effect on quantitative accuracy. Visualization of transit or pooling of Rb-82 in the vessels in the axilla was the most consistent feature when saturation occurred. Reduction of administered activity to 1110 MBq (30 mCi) and subsequent evaluation of 159 patients ensured successful MBF quantification while maintaining good diagnostic quality perfusion imaging in 99% of cases. MBF quantification and good-quality standard perfusion imaging can be performed on a high count rate PET system using a single-acquisition protocol. The administered activity requires optimization and we recommend 1110 MBq for PET MPI with a Biograph mCT.

Extended cervical mediastinoscopy: mature results of a clinical protocol for staging bronchogenic carcinoma of the left lung

The objective of this study is to evaluate the accuracy of extended cervical mediastinoscopy (ECM) in the staging of bronchogenic carcinoma (BC) of the left lung based on our updated experience. From 1998 to 2003, 89 patients underwent routine ECM for staging of BC of the left lung. In 2004, routine positron emission tomography (PET) was included in our staging protocol and ECM was reserved for those with positive mediastinal or hilar PET images, large lymph nodes on computed tomography (CT) scan or central tumours. Following this protocol, from 2004 to 2010, we performed 132 selective ECM. ECM was considered positive when metastatic nodes or tumour involvement directly in the subaortic or para-aortic regions was confirmed pathologically. Patients with negative ECM underwent subsequent thoracotomy for tumour resection and systematic nodal dissection (SND). Two hundred and twenty-one ECMs were performed from 1998 to 2010 (89 routine and 132 selective). In the routine ECM protocol, four cases were positive and thoracotomy was contraindicated. The remaining 85 patients were operated and five had nodal disease in subaortic (LN5) or para-aortic (LN6) stations. In the selective ECM protocol (n=188), 132 patients underwent ECM and in 19 it was positive; the remaining 113 patients underwent thoracotomy and SND found involved LN5 or LN6 in six patients; the other 56 patients underwent direct thoracotomy and four had positive LN5 or LN6. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ECM were 0.67, 1, 1, 0.94 and 0.95, respectively. The staging values of routine/selective ECM protocols were 0.44/0.65, 1/1, 1/1, 0.94/0.94 and 0.94/0.95, respectively. Selective ECM protocol according to CT and PET findings has high negative predictive value and accuracy. Therefore, its selective use is recommended because it saves around 30% ECM without decreasing staging values of the current protocol.