Fludeoxyglucose Research Articles

"Bilateral Hot Forearm Sign": Ingeminating the Pattern of Physiological Uptake of 18F-Fludeoxyglucose.

Exertion and exercise increase glucose metabolism within the skeletal muscles causing increased fludeoxyglucose (FDG) uptake on 18F-FDG positron emission tomography/computed tomography (PET/CT). Here, we present findings of 18F-FDG PET/CT in a patient with acute viral hepatitis A-induced liver failure with multiple foci of pyoderma and incessant itching resulting in increased FDG uptake in the muscles of the bilateral forearm, producing the "bilateral hot forearm sign."

Cardiac fludeoxyglucose-18 positron emission tomography in genotype-positive arrhythmogenic cardiomyopathy

BackgroundMyocardial inflammation contributes to the pathogenesis of arrhythmogenic cardiomyopathy (ACM), a clinically and genetically heterogenous disorder. Due to phenotypic overlap, some patients with genetic ACM may be evaluated for an underlying inflammatory cardiomyopathy. However, the cardiac fludeoxyglucose (FDG) positron emission tomography (PET) findings in ACM patients have not been elucidated. MethodsAll genotype-positive patients in the Mayo Clinic ACM registry (n = 323) who received a cardiac FDG PET were included in this study. Pertinent data were extracted from the medical record. ResultsCollectively, 12/323 (4%; 67% female) genotype-positive ACM patients received a cardiac PET FDG scan as part of their clinical evaluation (median age at scan 49 ± 13 years). Amongst these patients, pathogenic/likely pathogenic variants were detected in LMNA (n = 7), DSP (n = 3), FLNC (n = 1) and PLN (n = 1). Of note, 6/12 (50%) had abnormal myocardial FDG uptake, including diffuse (entire myocardium) uptake in 2/6 (33%), focal (1–2 segments) uptake in 2/6 (33%) and patchy (3+ segments) in 2/6 (33%). Median myocardial standardized uptake value ratio was 2.1. Interestingly, LMNA-positive patients accounted for 3 out of 6 (50%) positive studies (diffuse uptake in 2 and focal uptake in 1). ConclusionAbnormal myocardial FDG uptake is common in genetic ACM patients undergoing cardiac FDG PET. This study further supports the role of myocardial inflammation in ACM. Further investigation is needed to determine role of FDG PET in diagnosis and management of ACM and investigate the role of inflammation in ACM.

Low Ankle-Brachial Index Relates to Alzheimer-Signature Cerebral Glucose Metabolism in Cognitively Impaired Older Adults.

Ankle-brachial index (ABI), an indicator of atherosclerosis or arterial stiffness, has been associated with Alzheimer's disease (AD) dementia and related cognitive impairment. Nevertheless, only limited information is available regarding its contribution to brain alterations leading to cognitive decline in late-life. We aimed to investigate the relationship of ABI with in vivo AD pathologies and cerebrovascular injury in cognitively impaired older adults. Total 127 cognitively impaired (70 mild cognitive impairment and 57 AD dementia) individuals, who participated in an ongoing prospective cohort study, were included. All participants underwent comprehensive clinical and neuropsychological assessment, ABI measurement, apolipoprotein E (APOE) ɛ4 genotyping, and multi-modal brain imaging including [11C] Pittsburgh Compound B (PiB)-positron emission tomography (PET) and [18F] fludeoxyglucose (FDG)-PET, and MRI. General linear model analysis showed significant relationship between ABI strata (low ABI: <1.00, normal ABI: 1.00-1.29, and high ABI: ≥1.30) and AD-signature region cerebral glucose metabolism (AD-CM), even after controlling age, sex, clinical dementia rating-sum of box, and APOE ɛ4 positivity (p = 0.029). Post hoc comparison revealed that low ABI had significantly lower AD-CM than middle and high ABI, while no difference of AD-CM was found between middle and high ABI. There was no significant difference of global Aβ deposition, AD-signature region cortical thickness, and white matter hyperintensity volume between the three ABI strata. Our findings suggest that lower ABI, likely related to atherosclerosis, may contribute to the aggravation of AD-related regional neurodegeneration in cognitively impaired older adults.

Abstract 12736: Cardiac Fludeoxyglucose-18 Positron Emission Tomography in Genotype-Positive Arrhythmogenic Cardiomyopathy

Introduction: Myocardial inflammation likely contributes to the pathogenesis of arrhythmogenic cardiomyopathy (ACM), a clinically and genetically heterogenous disorder characterized by ventricular dysfunction and potentially life-threatening ventricular arrhythmias. Due to phenotypic overlap, some patients with genetic ACM may have been evaluated for an underlying inflammatory cardiomyopathy, namely cardiac sarcoidosis. However, the cardiac fludeoxyglucose (FDG) positron emission tomography (PET) findings in ACM patients have not been assessed systematically. Methods: All genotype-positive patients in the Mayo Clinic ACM registry who received a cardiac FDG PET were included in this study. The cardiac FDG PET scan consisted of a resting myocardial perfusion scan with N13-ammonia as well as a F18-FDG scan after a high-fat diet to suppress physiologic FDG uptake. Pertinent demographic, genetic, imaging, and outcome data were extracted from the medical record. Results: Collectively, 12 (75% female) genotype-positive ACM patients received a cardiac PET FDG scan as part of their clinical evaluation (median age at scan 45.3 years [IQR 38.9-62.1]). Amongst these patients, pathogenic/likely pathogenic variants were detected in LMNA (n=7), DSP (n=3), FLNC (n=1), and PLN (n=1). Of note, 6/12 (50%) had abnormal myocardial FDG uptake, including diffuse (entire myocardium) uptake in 2/6 (33%), focal (1-2 segments) uptake in 2/6 (33%) and patchy (3+ segments) in 2/6 (33%). Median myocardial standardized uptake value ratio was 2.1 (IQR 1.5-2.6). Interestingly, LMNA -positive patients accounted for 3 out of 6 (50%) positive studies (diffuse uptake in 2 and focal uptake in 1). Conclusion: Myocardial FDG uptake is common in genetic ACM patients undergoing cardiac FDG PET. This finding further supports the role of myocardial inflammation in genetic ACM and demonstrates the ability of cardiac FDG PET to readily detect this phenomenon. Further investigation is needed to determine (i) the role of cardiac FDG PET in the evaluation of genetic ACM, (ii) if FDG uptake in genetic ACM has prognostic value and (iii) whether the attenuation of myocardial inflammation with immunosuppressive agents can impact the clinical course of inflammatory genetic ACMs.

Evaluation of Reconstruction Algorithms to Validate the NEMA Phantom Results in Clinical Scenario - A Comparative Study Using Time-of-Flight versus Non-Time-of-Flight Positron Emission Tomography Imaging.

Objectives:The objective is to standardize the reconstruction parameters for the time-of-flight (TOF) versus non-TOF positron-emission tomography/computed tomography (PET/CT) imaging data and validation of the same in a clinical setting.Methods:The four spheres (10.0/13.0/17.0/22.0 mm) of the PET phantom (NEMA IQ Nu 2-2001) were filled with four times higher activity of [18F]-NaF than the background (5.3kBq/mL). Imaging (image matrix – 128 × 128 × 47, 2 min, 3D model) was done using two different (TOF/non-TOF) PET scanners. Phantom data were reconstructed in TOF and non-TOF modes for lutetium–yttrium oxyorthosilicate and non-TOF mode for bismuth germanate-based PET scanners. The reconstructed data (by varying iteration and subsets) that provided the best image contrast and signal-to-noise ratio (SNR) were evaluated. The whole-body [18F]-fludeoxyglucose (FDG) PET/CT scans (7–8 frames; 2.0 min/frame) in 16 lymphoma patients were acquired at 60 min after injecting the radioactivity (370.0–444.0 MBq of [18F]-FDG. The clinical PET/CT data were reconstructed using phantom-derived reconstruction parameters and evaluated for image contrast and SNR of the detected lesions.Results:TOF reconstruction at second iteration provided significantly (P ≤ 0.02) higher SNR (20.7) and contrast (contrast recovery coefficient/background variability = 3.21) for the smallest hot lesions (10.0 mm) in the phantom than the non-TOF system. Similarly, in patient data analysis for the selected FDG avid lesions, the SNR values were significantly (P = 0.02) higher (13.3 ± 6.49) in TOF than (11 ± 6.48) in non-TOF system. Further, the small (≤10.0 mm) lesions were seen more distinctly in TOF system.Conclusion:It is thus observed that TOF reconstruction converged faster than the non-TOF, and the applicability of the same may impact the image quality and interpretation in the clinical PET data. The validation of the phantom-based experimental reconstruction parameters to clinical PET imaging data is highly warranted.

Phantom and clinical assessment of small pulmonary nodules using Q.Clear reconstruction on a silicon-photomultiplier-based time-of-flight PET/CT system

To evaluate the quantification accuracy of different positron emission tomography-computed tomography (PET/CT) reconstruction algorithms, we measured the recovery coefficient (RC) and contrast recovery (CR) in phantom studies. The results played a guiding role in the partial-volume-effect correction (PVC) for following clinical evaluations. The PET images were reconstructed with four different methods: ordered subsets expectation maximization (OSEM), OSEM with time-of-flight (TOF), OSEM with TOF and point spread function (PSF), and Bayesian penalized likelihood (BPL, known as Q.Clear in the PET/CT of GE Healthcare). In clinical studies, SUVmax and SUVmean (the maximum and mean of the standardized uptake values, SUVs) of 75 small pulmonary nodules (sub-centimeter group: < 10 mm and medium-size group: 10–25 mm) were measured from 26 patients. Results show that Q.Clear produced higher RC and CR values, which can improve quantification accuracy compared with other methods (P < 0.05), except for the RC of 37 mm sphere (P > 0.05). The SUVs of sub-centimeter fludeoxyglucose (FDG)-avid pulmonary nodules with Q.Clear illustrated highly significant differences from those reconstructed with other algorithms (P < 0.001). After performing the PVC, highly significant differences (P < 0.001) still existed in the SUVmean measured by Q.Clear comparing with those measured by the other algorithms. Our results suggest that the Q.Clear reconstruction algorithm improved the quantification accuracy towards the true uptake, which potentially promotes the diagnostic confidence and treatment response evaluations with PET/CT imaging, especially for the sub-centimeter pulmonary nodules. For small lesions, PVC is essential.

Comparison of different diagnostic approaches in the management of the clinically negative neck in early oral cancer patients

In clinically node‐negative patients with early oral cavity cancer, [18F]fludeoxyglucose (FDG) positron emission tomography–computed tomography (PET‐CT) should be compared with sentinel node biopsy. Cost effectiveness is one of the important aspects for implementation of FDG/PET‐CT in clinical practice for this patient population.

Differentiating Mild Cognitive Impairment, Alzheimer's Disease, and Dementia With Lewy Bodies Using Cingulate Island Sign on Perfusion IMP-SPECT.

The cingulate island sign (CIS) on fludeoxyglucose (FDG)-positron emission tomography (PET) is a supporting biomarker of dementia with Lewy bodies (DLB). Its diagnostic accuracy has only been investigated in FDG-PET, however. The present prospective study compared the CIS on I-iodoamphetamine-single photon emission computed tomography (SPECT) among patients with mild cognitive impairment (MCI), AD, or DLB. Fifty-eight patients with MCI, 42 with probable AD, and 58 with probable DLB were enrolled. The “CIScore” used to evaluate the CIS was defined as the ratio of volume of interest (VOI)-1 (indicating posterior cingulate gyrus [PCG]) to VOI-2 (area of significantly reduced regional cerebral blood perfusion [rCBF] in DLB patients compared with in healthy controls). It was calculated using eZIS software. The CIScore for MCI, DLB, and AD was 0.22, 0.23, and 0.28, respectively. The CIScore in the AD group was significantly higher than that in the DLB or MCI groups (AD vs. DLB: p < 0.001, AD vs. MCI: p < 0.005). This suggests that the CIScore can discriminate DLB from AD, if the decrease in rCBF in the PCG is similar between them. We believe that it is difficult to identify MCI based on the CIScore, as the decrease in rCBF in the PCG is not severe. The diagnostic accuracy of the CIScore may be low as it often shows an increase in elderly DLB patients, in whom the pathologically common form is most prevalent (1). Further study should include assessment of multiple components such as symptom classification and age.

Recil 2017 Criteria Demonstrated Similar Prognostic Value and Detected a Comparable Treatment Difference between Obinutuzumab- and Rituximab-Chemotherapy Compared with Cheson 2007 and Lugano 2014 Criteria in Patients with Previously Untreated Advanced-Stage Follicular Lymphoma

Recil 2017 Criteria Demonstrated Similar Prognostic Value and Detected a Comparable Treatment Difference between Obinutuzumab- and Rituximab-Chemotherapy Compared with Cheson 2007 and Lugano 2014 Criteria in Patients with Previously Untreated Advanced-Stage Follicular Lymphoma

Non‑invasive monitoring of paclitaxel and lenvatinib efficacy against anaplastic thyroid cancer in orthotopic SCID mouse models using small‑animal FDG‑PET/CT.

Anaplastic thyroid carcinoma (ATC) is a rare type of thyroid carcinoma with a poor prognosis. Thus, suitable preclinical tumor models are required for the development of new ATC therapies. In the present study, orthotopic tumor xenograft models were established using ATC cell lines and SCID mice, and tumor invasion and the effects of anticancer drugs were evaluated using positron emission tomography/computed tomography (PET/CT) to repeatedly and non‑invasively monitor these models. Three ATC cell lines (8305c, 8505c, and ACT‑1) were used. Their sensitivities to two anticancer drugs (paclitaxel and lenvatinib) were investigated. The 8505c cell line was orthotopically implanted into SCID mice, which were then divided into three groups: No chemotherapy, paclitaxel (5mg/kg, administered intraperitoneally, every week), and lenvatinib (5mg/kg, oral route, every day) groups. PET/CT was performed and tumor growth and the effects of anticancer drugs based on tumor volume and fludeoxyglucose (FDG) uptake were evaluated. 8505c cells exhibited the highest sensitivity to the anticancer drugs. In mice implanted with 8505c cells, continuous increases in FDG uptake associated with tumor growth were detected on PET/CT in the group that received no chemotherapy. The tumor volume and FDG uptake increased by 91.5‑ and 2.4‑fold, respectively, within 2weeks. The increase observed in tumor volume was 26.9‑ and 12.2‑fold in the paclitaxel and lenvatinib groups, respectively, within 2weeks. Furthermore, the increase in FDG uptake was 1.8 and 1.6‑fold in the paclitaxel and lenvatinib groups, respectively, within 2weeks. In our orthotopic SCID mouse model, tumor growth and the effects of anticancer drugs were repeatedly and non‑invasively monitored using PET/CT. The present method is useful for the development of new ATC treatments.

Complete Response Status According to RECIL 2017 Criteria Shows High Concordance with Lugano 2014 Criteria and Is Highly Prognostic for Outcome in Previously Untreated Patients with CD20-Positive Diffuse Large B-Cell Lymphoma (DLBCL)

Complete Response Status According to RECIL 2017 Criteria Shows High Concordance with Lugano 2014 Criteria and Is Highly Prognostic for Outcome in Previously Untreated Patients with CD20-Positive Diffuse Large B-Cell Lymphoma (DLBCL)

FDG PET-CT in pediatric Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) in pediatric patients presents with single-system or multisystem disease. Accurate staging is essential for selecting the most appropriate therapy ranging from local surgery to chemotherapy. A retrospective review was undertaken of reported fludeoxyglucose (FDG) positron emission tomography - computed tomography (PET-CT) scans performed in children with LCH from June 2006 to February 2017. Findings were compared with a reference standard of biopsy or informed clinical follow-up. One hundred nine scans were performed in 33 patients (age 7weeks to 18 years). Nineteen patients had single-system, bone unifocal disease; seven patients had single-system, bone multifocal disease; four patients had single-system, skin unifocal disease; two patients had multisystem disease; and one patient had single-system, lymph node disease. Twenty-six scans were performed to stage biopsy-proven LCH, and 83 scans were performed during follow-up to assess treatment response or recurrence after therapy completion. At staging, FDG PET-CT detected all sites of biopsy-proven LCH (except where bone unifocal disease had been resected). There was one false-positive thymic finding that resolved without therapy. The per-patient false-positive rate of FDG PET-CT at staging was 4% (1/26). During follow-up, five LCH recurrences and one case of progressive disease on therapy occurred, all positive on FDG PET-CT. During follow-up two patients had FDG PET-CT scans with false-positive findings and one patient with a magnetic resonance imaging false-positive finding. The per-scan false-positive rate of FDG PET-CT during follow-up was 2% (2/83). FDG PET-CT is highly sensitive for the staging and follow-up of pediatric patients with LCH, and has a very low false-positive rate.

Clinical impact of pre‐treatment FDG‐PET/CT staging of primary ovarian, fallopian tube, and peritoneal cancers in women

To assess the clinical impact of preoperative fludeoxyglucose (FDG) with positron emission tomography (PET) and computed tomography (CT) in women with ovarian, fallopian tube, or peritoneal cancer with focus on consequences of added findings (AFs). FDG-PET/CT was implemented as a standard imaging modality for women with newly diagnosed ovarian, fallopian tube, or peritoneal cancer at our institution in 2008. After full implementation, all preoperative scans were reviewed and AFs were evaluated from January 2011 to December 2012. Decisions regarding further examination made at the first multidisciplinary team conference were recorded. Subsequent procedures were tracked via medical records, and the impact of AFs on additional examinations, delay, and change in treatment plans was evaluated. Forty-four (21.1%) of 209 women presented with AFs. Further examination was performed in 35/44 (79.5%). Malignancy was identified in 15/35 (42.9%), revealing metastases from ovarian, fallopian tube, or peritoneal cancer in 11, a synchronous primary cancer in 3, and recurrence of a previous cancer in 1 woman. The ovarian, fallopian tube, or peritoneal cancer metastases were localized in the lungs, uterus, colon, vagina, and breasts. The remaining 20 AFs revealed 2 benign lesions and 1 pre-malignant lesion, whereas no abnormality was found in 17. Further examination of AFs resulted in a significant time delay until treatment start of median 4days (range 1-83days, P<0.004). Further examinations of AFs by FDG-PET/CT delayed time to start of treatment by median 4days in women with newly diagnosed ovarian, fallopian tube, or peritoneal cancer in a contemporary institution with fast-track access to additional diagnostics. The clinical implications of this must be balanced against the gain of detecting unrecognized malignancy in 15 of 209 women (7.2%).

Cells to Surgery Quiz: May 2019

Cells to Surgery Quiz: May 2019

Primary diagnosis of classic Hodgkin lymphoma by bone marrow aspirate and trephine – an unusual presentation with interesting morphology

An 82-year-old gentleman presented with breathlessness and a 3-month history of fevers and night sweats. Past history was remarkable for an unprovoked pulmonary embolism (PE) 10 months prior for which he had 6 months anticoagulation therapy with no specific malignancy diagnosed at that time. Further inpatient investigations revealed a recurrent PE and a subsequent positron emission tomography/computed tomography (PET/CT) scan showed retrocaval lymphadenopathy with fludeoxyglucose (FDG) avid nodes above and below the diaphragm with spleen, liver and marrow involvement. Staging bone marrow aspirate and trephine (BMAT) demonstrated large bilobed Hodgkin Reed-Sternberg (HRS) cells with lymphocyte rosetting. Trephine histology showed focal collections of large HRS cells with an accompanying inflammatory cell infiltrate. The HRS cells were CD15+/CD30+/PAX5(weak) on immunohistochemistry (IHC). A diagnosis of Classic Hodgkin Lymphoma (CHL) was established based on the marrow findings. Hodgkin lymphoma (HL) with bone marrow (BM) involvement is a relatively infrequent finding (∼5% cases of HL)1,2 and the presence of HRS cells in BM aspirate is rare. This case illustrates an unusual clinical presentation of CHL with primary diagnosis attained by BM biopsy. The patient was commenced on chlorambucil, procarbazine, prednisolone and vinblastine (Ch1VPP) chemotherapy and restaging PET/CT after 6 cycles showed marked interval improvement of FDG avid disease.

Imaging in myeloma with focus on advanced imaging techniques.

In recent years, there have been major advances in the imaging of myeloma with whole body MRI incorporating diffusion-weighted imaging, emerging as the most sensitive modality. Imaging is now a key component in the work-up of patients with a suspected diagnosis of myeloma. The International Myeloma Working Group now specifies that more than one focal lesion on MRI or lytic lesion on whole body low-dose CT or fludeoxyglucose (FDG) PET/CT fulfil the criteria for bone damage requiring therapy. The recent National Institute for Health and Care Excellence myeloma guidelines recommend imaging in all patients with suspected myeloma. In addition, there is emerging data supporting the use of functional imaging techniques (WB-DW MRI and FDG PET/CT) to predict outcome and evaluate response to therapy. This review summarises the imaging modalities used in myeloma, the latest guidelines relevant to imaging and future directions.

Regionally surgical resection of stage-IV adenocarcinoma acquired tyrosine kinases inhibitor-resistance.

A 65-year-old male presented with a mass at left lower lobe (LLL) in November 2010, without a history of smoking. Computer tomography (CT) and positron emission tomography (PET)-CT scans showed a 41 mm × 38 mm solid mass at LLL with small nodules interspersed in both lungs. The largest nodule had a maximum diameter of about 12 mm at left upper lobe (LUL) and was considered to be a metastasis according to fludeoxyglucose (FDG)-PET result. The biopsy guided by CT pathologically confirmed lung adenocarcinoma of the primary lesion.

Differentiated thyroid cancer theranostics: radioiodine and beyond.

The term theranostics is the combination of a diagnostic tool that helps to define the right therapeutic tool for specific disease. It signifies the "we know which sites require treatment (diagnostic scan) and confirm that those sites have been treated (post-therapy scan)" demonstrating the achievable tumor dose concept. This term was first used by John Funkhouser at the beginning of the 90s, at the same time the concept of personalized medicine appeared. In nuclear medicine, theranostics is easy to apply and understand because of an easy switch from diagnosis to therapy with the same vector. It helps in maximizing tumor dose and sparing normal tissue with high specific and rapid uptake in metastasis. The oldest application of this concept is radioactive iodine I-131 (RAI). The first treatment based on the theranostic concept was performed on thyroid cancer patients with RAI in 1946. From then on management of differentiated thyroid cancer (DTC) has evolved on the multimodality concept. We now use the term "our" patient instead of "my" patient to signify this. However, the initial surgical management followed by RAI as per the theranostics has remained the mainstay in achieving a cure in most of DTC patients. The normal thyroid cells metabolise iodine, the principle of which is utilized in imaging of the thyroid gland with isotopes of iodine. RAI treatment of DTC is based on the principle of sodium iodide symporter (NIS) expressing thyroid cells with DTC cells having the ability of trapping circulating RAI successfully helping in treatment of residual and metastatic disease. NIS is usually negative in poorly differentiated cells and is inversely proportional to Glucose transporter receptor Type 1 expression. Both positive and negative NIS are the key components of the theranostic approach in treatment of DTC. Presence or absence of NIS is documented by either whole body iodine scintigraphy (WBS) or 2-deoxy-2(18F) fludeoxyglucose (FDG) positron emission tomography computed tomography (PET-CT). Currently, single photon emission CT and CT (SPECT-CT) has significantly improved the precision and sensitivity of whole body iodine scintigraphy with its capability of accurate localization of disease foci whether iodine avid or non-avid. This has helped in a more personalized approach in treatment. This review will give an overview of the role of NIS in the theranostic approach to management with RAI, its current status and also the molecular approach to treatment in RAI refractory disease.

Futureproofing [18F]Fludeoxyglucose manufacture at an Academic Medical Center

BackgroundWe recently upgraded our [18F]fludeoxyglucose (FDG) production capabilities with the goal of futureproofing our FDG clinical supply, expanding the number of batches of FDG we can manufacture each day, and improving patient throughput in our nuclear medicine clinic. In this paper we report upgrade of the synthesis modules to the GE FASTLab 2 platform (Phase 1) and cyclotron updates (Phase 2) from both practical and regulatory perspectives. We summarize our experience manufacturing FDG on the FASTLab 2 module with a high-yielding self-shielded niobium (Nb) fluorine-18 target.ResultsFollowing installation of Nb targets for production of fluorine-18, a 55 μA beam for 22 min generated 1330 ± 153 mCi of [18F]fluoride. Using these cyclotron beam parameters in combination with the FASTLab 2, activity yields (AY) of FDG were 957 ± 102 mCi at EOS, corresponding to 72% non-corrected AY (n = 235). Our workflow, inventory management and regulatory compliance have been greatly simplified following the synthesis module and cyclotron upgrades, and patient wait times for FDG PET have been cut in half at our nuclear medicine clinic.ConclusionsThe combination of FASTlab 2 and self-shielded Nb fluorine-18 targets have improved our yield of FDG, and enabled reliable and repeatable manufacture of the radiotracer for clinical use.

Comparison of hybrid 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging and positron emission tomography/computed tomography for evaluation of peripheral nerve sheath tumors in patients with neurofibromatosis type 1.

Rapidly enlarging, painful plexiform neurofibromas (PN) in neurofibromatosis type 1 (NF1) patients are at higher risk for harboring a malignant peripheral nerve sheath tumor (MPNST). Fludeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) has been used to support more invasive diagnostic and therapeutic interventions. However, PET/CT imparts an untoward radiation hazard to this population with tumor suppressor gene impairment. The use of FDG PET coupled with magnetic resonance imaging (MRI) rather than CT is a safer alternative but its relative diagnostic sensitivity requires verification. Ten patients (6 females, 4 males, mean age 27 years, range 8–54) with NF1 and progressive PN were accrued from our institutional NF Clinic. Indications for PET scanning included increasing pain and/or progressive disability associated with an enlarging PN on serial MRIs. Following a clinically indicated whole-body FDG PET/CT, a contemporaneous PET/MRI was obtained using residual FDG activity with an average time interval of 3–4 h FDG-avid lesions were assessed for both maximum standardized uptake value (SUVmax) from PET/CT and SUVmax from PET/MR and correlation was made between the two parameters. 26 FDG avid lesions were detected on both PET/CT and PET/MR with an accuracy of 100%. SUVmax values ranged from 1.4–10.8 for PET/CT and from 0.2-5.9 for PET/MRI. SUVmax values from both modalities demonstrated positive correlation (r = 0.45, P < 0.001). PET/MRI radiation dose was significantly lower (53.35% ± 14.37% [P = 0.006]). In conclusion, PET/MRI is a feasible alternative to PET/CT in patients with NF1 when screening for the potential occurrence of MPNST. Reduction in radiation exposure approaches 50% compared to PET/CT.