Body PET Research Articles

Human biodistribution and internal dosimetry of 4-[ 18F]fluorobenzyl-dexetimide: a PET radiopharmaceutical for imaging muscarinic acetylcholine receptors in the brain and heart

Background4-[18F] fluorobenzyl dexetimide (F-DEX) is the first non-subtype selective fluorine-18 labelled tracer for muscarinic receptors (mAChR) used in humans. A recent first-in-human study found high regional brain uptake with low variation in normal subjects. Disturbance of mAChR has been reported in Alzheimer’s and Parkinson’s disease, schizophrenia and depression and various cardiac diseases. The following work assesses the biodistribution, organ tracer kinetics and radiation dose associated with F-DEX.MethodDose calculations were based on activity uptake derived from multiple time point whole body PET CT imaging and the organ-specific dosimetric S-factors derived from the ICRP 133 standard man and woman mathematical phantoms. Effective doses were calculated using the latest ICRP tissue weighting factors.ResultsSerial images and time activity curves demonstrate high brain and left ventricular myocardial uptake (5% and 0.65% of injected activity, respectively) with greater retention in brain than myocardium. The mean effective dose was in concordance with other 18F labelled tracers at 19.70 ± 2.27 μSv/MBq. The largest absorbed doses were in the liver (52.91 ± 1.46 μGy/MBq) and heart wall (43.94 ± 12.88 μGy/MBq) for standard man and the liver (61.66 ± 13.61 μGy/MBq) and lungs (40.93 ± 3.11 μGy/MBq) for standard woman. The absorbed dose to all organs, most notably, the red bone marrow (20.03 ± 2.89 μGy/MBq) was sufficiently low to ensure no toxicity after numerous follow-up procedures.ConclusionsThe radiation dose associated with an administration of F-DEX is comparable to that of other 18F labelled tracers such as FDG (19.0 μSv/MBq) and lower than tracers used for SPECT imaging of muscarinic receptors (I-DEX 28.5 μSv/MBq). Clinical use would likely result in an effective dose less than 4 mSv for the ICRP 133 standard phantoms after dose optimisation allowing justification for numerous follow-up procedures. Recent results from first in-human studies and a comparatively low radiation dose make F-DEX an attractive option for future applications of imaging muscarinic receptors in the brain. Further investigation of the potential of F-DEX for imaging parasympathetic innervation of the heart may be warranted.

Biodistribution, dosimetry, and temporal signal-to-noise ratio analyses of normal and cancer uptake of [68Ga]Ga-P15-041, a gallium-68 labeled bisphosphonate, from first-in-human studies

Introduction[68Ga]Ga-P15-041 ([68Ga]Ga-HBED-CC-BP) is a novel bone-seeking PET radiotracer that can be generator-produced. We undertook a Phase 0/I clinical trial to assess its potential for imaging bone metastases in prostate cancer including assessment of radiotracer biodistribution and dosimetry. MethodsSubjects with prostate cancer and known or suspected osseous metastatic disease were enrolled into one of two arms: dosimetry or dynamic. Dosimetry was performed with 6 whole body PET acquisitions and urine collection spanning 3 h; normal organ dosimetry was calculated using OLINDA/EXM. Dynamic imaging included a 60 min acquisition over a site of known or suspected disease followed by two whole body scans. Bootstrapping and subsampling of the acquired list-mode data were conducted to recommend image acquisition parameters for future clinical trials. ResultsUp to 233 MBq (6.3 mCi) of [68Ga]Ga-P15-041 was injected into 12 enrolled volunteers, 8 in dosimetry and 4 in dynamic cohorts. Radiotracer accumulated in known bone lesions and cleared rapidly from blood and soft tissue. The highest individual organ dose was 0.135 mSv/MBq in the urinary bladder wall. The average effective dose was 0.0173 ± 0.0036 mSv/MBq. An average injected activity of 166.5 MBq (4.5 mCi) resulted in absorbed dose estimates of 22.5 mSv to the urinary bladder wall, 8.2 mSv to the kidneys, and an effective dose of 2.9 mSv. Lesion signal to noise ratios on images generated from subsampled data were significantly higher for injected activities above 74 MBq (2 mCi) and were also significantly higher for imaging at 90 min than at 180 min post-injection. ConclusionsDosimetry estimates are acceptable and [68Ga]Ga-P15-041 uptake characteristics in patients with confirmed bone metastases support its continued development. Advances in knowledge and implications for patient careUse of [68Ga]Ga-P15-041 would not require cyclotron infrastructure for manufacturing and distribution, allowing for improved patient access to a promising PET bone imaging agent.

Total Body PET Imaging From Mice to Humans

Small animal PET scanning is destined to offer programs of the pre-clinical development of paradigms and protocols that are translatable for undertaking “systems biology” research in humans using total body PET Scanning.

Total Body PET: Why, How, What for?

PET instruments are now available with a long axial field-of-view (LAFOV) to enable imaging the total-body, or at least head and torso, simultaneously and without bed translation. This has two major benefits, a dramatic increase in system sensitivity and the ability to measure kinetics with wider axial coverage so as to include multiple organs. This manuscript presents a review of the technology leading up to the introduction of these new instruments, and explains the benefits of a LAFOV PET-CT instrument. To date there are two platforms developed for TB-PET, an outcome of the EXPLORER Consortium of the University of California at Davis (UC Davis) and the University of Pennsylvania (Penn). The uEXPLORER at UC Davis has an AFOV of 194 cm and was developed by United Imaging Healthcare. The PennPET EXPLORER was developed at Penn and is based on the digital detector from Philips Healthcare. This multi-ring system is scalable and has been tested with 3 rings but is now being expanded to 6 rings for 140 cm. Initial human studies with both EXPLORER systems have demonstrated the successful implementation and benefits of LAFOV scanners for both clinical and research applications. Examples of such studies are described in this manuscript.

Synchronous Mucinous Tubular and Spindle Cell Carcinoma of the Kidney and Papillary Carcinoma of the Thyroid

A 55 year old female, presented with flank pain and fullness since 2 years. On examination, a 10x10cm, ballotable lump was present in the right flank. CT Abdomen showed a 9.5x8.8 cm, exophytic mass lesion in the right kidney with patchy arterial enhancement and heterogenous enhancement in the venous phase. Whole body PET CT showed well defined, metabolically active masses in the right kidney, thyroid and cervical lymph nodes. Nephrectomy specimen received, showed a tumor measuring 12x7x6.5 cm creamy-white, fleshy, replacing the kidney. Histopathology revealed an unusual renal neoplasm with tubule formation merging with bland spindle cells and a focal myxoid stroma. Tumor cells were immunoreactive for CK7, EMA, vimentin and were negative for PAX8, CD10 & AMACR. The diagnosis of Mucinous Tubular and Spindle cell carcinoma (MTSCC) was established. FNAC of the thyroid nodules showed a classic papillary thyroid carcinoma.

Diagnostic evaluation of PET CT, USG neck & FNAC in clinically N0 neck

Introduction : Extent of neck dissection is determined by the neck nodal positivity and indirectly has a bearing on neck dissection related morbidity. The current study prospectively compares the accuracy of these imaging techniques and FNAC to final histopathology. 31 patients of Oral cavity squamous cell carcinoma with no palpable lymphadenopathy were prospectively included in the study. Methodology : Thirty-one patients of oral cavity SCC who did not have any clinical lymphadenopathy treated at our centre from January 2018 to July 2018 were recruited for the study. All these patients underwent a whole body PET with contrast enhanced CT followed by a high-resolution ultrasound of the neck. Patients then underwent a US guided FNAC of the most suspicious lymph node. Results: 14 of the 31 patients had pathologically positive neck node. PET CT had 100 % negative predictive value. USG Neck diagnosed 22 patients to have suspicious lymph node with a negative predicitve value of 66.7% and positive predictive value of 50%. The combined yield of PET CT and USG Neck could produce a PPV of 100% and NPV of 68%. Conclusion : None of the test individually could predict the neck nodal positivity with absolute accuracy in our study. The best accuracy was when a combination of these tests were done.

Evaluation of a Bayesian penalized likelihood reconstruction algorithm for low-count clinical 18F-FDG PET/CT

BackgroundRecently, a Bayesian penalized likelihood (BPL) reconstruction algorithm was introduced for a commercial PET/CT with the potential to improve image quality. We compared the performance of this BPL algorithm with conventional reconstruction algorithms under realistic clinical conditions such as daily practiced at many European sites, i.e. low 18F-FDG dose and short acquisition times.ResultsTo study the performance of the BPL algorithm, regular clinical 18F-FDG whole body PET scans were made. In addition, two types of phantoms were scanned with 4-37 mm sized spheres filled with 18F-FDG at sphere-to-background ratios of 10-to-1, 4-to-1, and 2-to-1. Images were reconstructed using standard ordered-subset expectation maximization (OSEM), OSEM with point spread function (PSF), and the BPL algorithm using β-values of 450, 550 and 700. To quantify the image quality, the lesion detectability, activity recovery, and the coefficient of variation (COV) within a single bed position (BP) were determined. We found that when applying the BPL algorithm both smaller lesions in clinical studies as well as spheres in phantom studies can be detected more easily due to a higher SUV recovery, especially for higher contrast ratios. Under standard clinical scanning conditions, i.e. low number of counts, the COV is higher for the BPL (β=450) than the OSEM+PSF algorithm. Increase of the β-value to 550 or 700 results in a COV comparable to OSEM+PSF, however, at the cost of contrast, though still better than OSEM+PSF. At the edges of the axial field of view (FOV) where BPs overlap, COV can increase to levels at which bands become visible in clinical images, related to the lower local axial sensitivity of the PET/CT, which is due to the limited bed overlap of 23% such as advised by the manufacturer.ConclusionsThe BPL algorithm performs better than the standard OSEM+PSF algorithm on small lesion detectability, SUV recovery, and noise suppression. Increase of the percentage of bed overlap, time per BP, administered activity, or the β-value, all have a direct positive impact on image quality, though the latter with some loss of small lesion detectability. Thus, BPL algorithms are very interesting for improving image quality, especially in small lesion detectability.

Depth encoding PET detectors using single layer crystal array with different reflector arrangements along depths

Abstract Depth encoding detectors are preferred for PET scanners with a small ring diameter and a long axial field of view. In this work, novel depth encoding detectors using different inter-crystal reflector arrangements along the depth of single layer crystal arrays are proposed and their performance is evaluated. As compared to the previous four-layer detector with different reflector arrangements, the detectors proposed in this work are expected to improve the energy and timing resolution of the detectors. 4 × 4 LYSO arrays with a crystal size of 3 × 3 × 20 mm3 and 6 × 6 LYSO arrays with a crystal size of 2 × 2 × 20 mm3 are fabricated using two and four reflector arrangements along the crystal’s depth. The LYSO arrays are single-ended read out by 4 × 4 SiPM arrays with a pixel size of 3 × 3 mm2. The first and second half of the crystals are clearly resolved from the flood histograms for the two detectors with two reflector arrangements. 80% of the events can be correctly assigned to each half. The detectors provide a two layer depth encoding capability. The photopeak value and average energy resolution of the first and second half of the crystal are almost the same. The average crystal energy resolutions of the 4 × 4 and 6 × 6 LYSO arrays with two reflector arrangements are 10.4% and 11.6%, respectively. The timing resolutions of the two detectors are 284 ps and 442 ps for an energy window of 400 ∼ 600 keV. However, each quarter of the crystals cannot be clearly resolved for the two detectors with four reflector arrangements and further optimization is still required. The detectors developed in this work simultaneously provide a two layer depth encoding capability, good energy and timing resolution, and show great promise for developing high performance dedicated brain, whole body and total body PET scanners in the future.

A Case of Sarcoidosis Presenting as Refractory Arrhythmias: Quieting the Storm

Introduction Sarcoidosis is a multisystem granulomatous disorder of unknown etiology. Cardiac sarcoidosis can manifest as conduction abnormality, ventricular tachycardia (VT), heart failure or sudden cardiac death. Although well studied in the literature, we present an uncommon case of arrhythmia as a presenting manifestation of this disease. Case 45-year-old female with no significant past medical history presented with acute onset shortness of breath and palpitations. Initial transthoracic echocardiogram revealed an ejection fraction of 50%. Electrophysiology (EP) study showed a chemically inducible accelerated idioventricular rhythm with right bundle morphology. Left heart catheterization showed angiographically normal vessels and cardiac MRI showed no regional wall motion abnormalities or abnormal delayed enhancement. Patient presented to the hospital again due to recurrence of arrhythmia, found to be VT. Nuclear medicine whole body PET scan showed perfusion defects consistent with cardiac sarcoidosis. A mediastinal lymph node biopsy demonstrated focal non-granulomatous inflammation. Patient was initiated on anti-arrhythmics and underwent a single-chamber ICD placement. She continued to have episodes of wide QRS tachycardia, and was evaluated by Advanced Heart Failure for refractory arrhythmias. Decision-making Patient was initially managed with Amiodarone and a beta-blocker. Due to unstable VT, she was taken to EP lab where a focal origin of the VT was successfully found in the basal anterolateral endocardial left ventricle and at the base of one of the papillary muscles. Ablations were performed in these areas with reduction in VT rate. Patient was also discovered to have complete atrioventricular block. Subsequently, she developed recurrence of arrhythmia and was admitted again for VT management. Patient was taken back to the EP lab for an endocardial and epicardial ablation. A focal VT source was found in the apical lateral left ventricle. Due to proximity of the phrenic nerve to the site, no ablations were performed. However, due to recurrence of arrhythmia, she was taken back to the lab for a third ablation in the epicardial area with resulting success. Antiarrhythmics were changed to Flecainide which has since suppressed her VT. Patient has been maintained on Methotrexate, Hydroxychloroquine, and Prednisone for continued sarcoid therapy. We are using periodic F-FDG PET imaging to monitor the severity of myocardial inflammation. Based on patient's clinical status and PET imaging, we have determined the time to wean immunosuppressant agents. Conclusion Cardiac sarcoidosis affects at least 25% of sarcoidosis patients and accounts for substantial mortality and morbidity.Ventricular arrhythmias may be the presenting symptom of cardiac sarcoidosis and are challenging to treat. Risk stratification through proposed techniques such as advanced cardiac imaging and EP studies is integral in this population. Recognition of sarcoidosis as a possible etiology of arrhythmias through integration of clinical and imaging findings can lead to appropriate lifesaving treatments.

Preliminary investigations into the use of the five-point body condition scale (Size-O-Meter) and its use in pet owner education

Rabbits are popular domestic pets, and effective educational resources can help owners understand their complex husbandry and health requirements. A five-point body condition scoring scheme is validated for some domestic species and is widely used by veterinarians. It can also assist pet owners in assessing and recognising variations in their pet's body condition that may indicate or predispose to disease or require nutritional adjustments. This study evaluated rabbit owners’ ability to use a rabbit species-specific body condition scoring scheme on their pets. A cross-sectional, prospective, questionnaire-based study was carried out in one small animal veterinary practice in Edinburgh, Scotland. A single questionnaire was given to all rabbit owners (existing and new) at appointment check-in over a 4-month period. They were asked to body condition score their own animals in a controlled environment using a five-point body condition scoring scheme designed for rabbits (Size-O-Meter). Their participation was optional. A single veterinarian then scored the same rabbits using the same system. Data were collected from 64 owners and 69 rabbits. The majority of owners (64%) scored their pets as the veterinarian did, even though 74% of owners had never seen the scheme previously. Three-quarters (75%) of owners assigned a score between 2.5 and 3.5, which is considered the ideal body condition range. A Bland-Altman Plot was conducted which showed little bias between the owner and veterinarian scores indicating that the scores were likely within one condition grade of each other. This preliminary study suggests that the use of the rabbit Size-O-Meters may be beneficial in aiding rabbit owners in assessing the current body condition of their rabbit. Results suggest that despite efforts, current pet owner exposure to rabbit-specific body condition scoring schemes is poor. Increasing the exposure of rabbit owners to the body condition scoring scheme in veterinary practice could play a role in aiding the achievement of appropriate body condition in pet rabbits, and identification of fluctuations in body condition that may indicate disease or require intervention.

076 A rare case of anti-glutamate decarboxylase antibody syndrome presenting with recurrent vomiting

IntroductionAnti-glutamte decarboxylase antibody (anti-GAD) has been linked with various neurological syndromes including stiff-person syndrome, limbic encephalopathy, cerebellar ataxia, eye movement disorders and epilepsy (collectively known as ‘anti-GAD positive neurological syndromes’).1 We describe a very atypical phenotypic presentation of anti-GAD syndrome with unexplained vomiting and weight loss.CaseA 46 years old lady with no past medical or family history of note, presented with 6 months history of severe headaches and recurrent attacks of episodic vomiting (4–6 episodes of multiple vomiting daily) with no identified precipitant and complete normality in between the episodes with no other associated symptoms. She reported 15 kg of unintentional weight loss. Neurological examination and investigations including MRI brain, CT angiogram and liver enzymes, immunoglobulins, thyroid function, vasculitic screen were normal. Upper GI endoscopy, gastric emptying studies, CT imaging of chest, abdomen and pelvis and whole body PET scan were unremarkable. Serum autoimmune antibody screen was positive with high titre of anti-GAD antibody (1200 kU/liter). The cerebrospinal fluid anti-GAD antibody titre was raised at 103.7 kU/liter with otherwise normal parameters including negative oligoclonal bands. The nerve conduction studies did not show continuous motor activity or spasmodic reflex myoclonus (seen in stiff-person syndrome).2 A therapeutic trial of immunosuppression was introduced with moderate improvement in symptoms.ConclusionAnti-GAD neurological syndromes are rare and this is a unique presentation of the same. It is not completely understood why the presence of one antibody causes varied syndromes. The hypothesis is that the recurrent vomiting is possibly due to diaphragmatic spasms.ReferencesSaiz A, Blanco Y, Sabater L, et al. Spectrum of neurological syndromes associated with glutamic acid decarboxylase antibodies: diagnostic clues for this association. Brain 2008;131:2553–2563.Buechner S, Florio I, Capone L. Stiff person syndrome: A rare neurological disorder, heterogeneous in clinical presentation and not easy to treat. Case Rep Neurol Med2015; 2015:278065.

IMMUNOCHEMORADIOTHERAPY OR IMMUNOCHEMOTHERAPY ONLY IN PATIENTS WITH EXTRANONAL DIFFUSE LARGE B‐CELL LYMPHOMA OF STOMACH

Introduction: Radiation therapy (RT) is an effective method for treating indolent lymphomas of the stomach (Yahalom, 2006), but the results proving its role in patients with extranodal diffuse large B-cell lymphoma with predominant lesions of the stomach during chemoradiation treatment are few and conflictive (Metijharissi et al., 2017, Mehmood, 2017). The purpose of the study: is to evaluate the effectiveness of immunochemoradiotherapy (ICT + RT) compared with only ICT in patients with extranodal diffuse large B-cell lymphoma of the stomach. Methods: The study included 66 primary patients aged 25-90 years (mean age - 59 years), who received and completed in the period 2006-2017. ICT + RT (26 patients) or ICT only (40 patients). Of these, men - 32; women - 34; Stage I - 6, II - 30; III - 3; IV - 27. The average observation period of the group - 45 months. 63 patients received 4-8 cycles of ICT R-CHOP-21, 3 patients - DA-EPOCH-R. RT was performed after ICT at doses of 30-40 Gy for the entire volume of the stomach and in perigastric lymph nodes. In 10 patients before treatment, 3 weeks after ICT (20 patients) and 4 weeks after RT (15 patients), a full body PET scan with 18F-FDG was performed. The groups were comparable in terms of the main prognostic factors for the IPI criteria. Patients, who received surgical treatment were not included into the study. Five patients from the ICT group with a lack of efficacy of R-CHOP-21 were treated with 2 therapy lines, 1 - the third line of therapy. Results: A complete response after R-CHOP-21 was established in 48 of 66 (73%) patients. After subsequent RT in all 26 patients of the group of ICT + RT, complete remission was achieved in terms from 7 to 93 months. (average - 50 months.). In the group of ICT only, 5 patients died (4 of them in stage IV), including 4 from the underlying disease advance, 1 - from relapse in the central nervous system. The average follow-up period for this group was 42 months, the deceased patients — 10 months. The overall 5-year survival rate of the combined treatment group is 100%, ICT is 72%. In patients with PET positive results after PCT after irradiation, the metabolic activity of the tumour was not detected. Conclusion: ICT+RT is the optimal method of treating patients with extranodal aggressive lymphoma with gastric lesions. Keywords: diffuse large B-cell lymphoma (DLBCL); extranodal lymphomas.

Performance of a depth encoding PET detector module using light sharing and single-ended readout with SiPMs

Detectors with depth encoding capability, good energy resolution and good timing resolution are required to develop high performance whole body and total body PET scanners. In this work, an 8 × 8 LYSO array with crystal size of 3 × 3 × 20 mm3 was fabricated by using coupling materials that included 5 mm optical glue, 9 mm triangle ESR reflector and 6 mm rectangle ESR reflector from the top to the bottom in between adjacent crystals in one direction. The LYSO array was single-ended read out by an 8 × 8 SiPM array with one-to-one coupling. Row and column summing circuit was used to read out the SiPM signals. The depth of interaction (DOI) of the detector was measured with the depth dependent light sharing between adjacent crystals while maintaining acceptable energy resolution and timing resolution. The performance of the detector module was evaluated. All crystals can be clearly resolved from the measured flood histogram. An average DOI resolution of 4.62 mm and an average timing resolution of 518 ps are obtained for events with E > 400 keV. The average energy resolution of the detector is 13.5%. This work provides a cost-effective depth encoding detector module that can be used to build high performance whole body and total body PET scanners in the future.

P3.08-15 Lung Squamous Cell Carcinoma with Solitary Ocular Metastasis，Successful Treatment: An Interesting and Rare Case Report

The incidence of ocular metastases from lung cancer is reported to be 0.1%-7% according to the international literature. Adenocarcinoma and small-cell lung cancer occupied the most proportion. Lung squamous cell carcinoma with solitary symptomatic ocular metastasis as the initial manifestation who accepted the multidisciplinary team (MDT) treatment has never been reported. In the diagnosis of intracranial disease, ophthalmofundoscopy can be used for follow-up observation and evaluation of therapeutic effects. Whole body PET -CT imaging can be used to identify the primary cancer and determine the disease staging. A 62-year-old woman presented to ophthalmology of hospital with a 1-week history of left eye pain, blurred vision. The ophthalmologist performed ophthalmofundoscopy and optical coherence tomography on the patient(Fig.1A). The ophthalmologist initial diagnosis is metastatic carcinoma to the eye. The diagnostic work was completed with PET-CT which confirmed the central lung cancer in the lower lobe of the right lung with ocular metastasis. After multiple disciplinary team consultations, including surgery, internal medicine, ophthalmology, radiotherapy and imaging department, the patient underwent the right lower lobe resection and lymph node dissection in December 2016. Postoperative pathology diagnose the right lung-squamous-cell carcinoma staged T2aN1. In February 2017, the patient reviewed the eye examination and indicated that the ocular lesions were enlarged. The patient received 4 courses of gemcitabine plus cisplatin regimen chemotherapy. The eye symptoms disappeared completely after 4 courses (Fig.2B). The progression-free time was 11.9 months. There're 16.5 months for the patients has been followed up (March, 2018) from surgery, and the lesion of ocular was still controlled very well without any specific ocular treatment. It's the first report of a rare case with solitary ocular metastasis as the initial manifestation of lung squamous cell carcinoma. The successful treatment of this case was reported to provide a new therapeutic reference for clinicians to encounter similar cases in the future.

An Unusual Cause of Obscure Gastrointestinal Bleeding Unmasked by Video Capsule Endoscopy

Follicular lymphoma (FL) is the most common type of non-Hodgkin's lymphoma in the West, usually detected in lymph nodes. Gastrointestinal tract (GIT) is a common site of extra-nodal disease. We report a case of atypical GI-FL diagnosed as a consequence of investigations for microcytic anemia. A 73-year-old gentleman was referred for evaluation of iron-deficiency anemia, presumed GI source. Physical examination was grossly normal. Initial age-appropriate colonoscopy revealed a cecal hyperplastic polyp and non-bleeding internal hemorrhoids. Six weeks later, upper endoscopy for new-onset melena revealed grade C esophagitis, erosive gastritis, and single small angioectasia in anterior duodenal bulb, unlikely to account for the severity of blood loss. Duodenal biopsy was negative for celiac disease. Video capsule endoscopy (VCE) was performed for worsening anemia necessitating blood transfusion. Active oozing spot amongst an area of erythema, erosions, small ulcers and likely luminal narrowing and stricture was evident in the distal jejunum/proximal ileum. The capsule did not reach the cecum. Due to retained capsule and luminal stricture, CT enterography was performed. This revealed large anterior mediastinal, retroperitoneal, pelvic masses and extensive severe small bowel wall thickening, compatible with possible nodal and extra-nodal metastatic lymphoma. The capsule has since passed. Subsequent pelvic mass biopsy showed low-grade FL. Further staging including PET confirmed atypical involvement with most intense uptake in the mesentery, omentum and pleura, and extensive nodal and bone marrow involvement. GI-FL is a rare entity, generally affecting the small intestines. It is not always possible to determine the primary site of origin of GI-FL. It could either arise from extra-intestinal regions and present in the GIT at an advanced stage, or arise primarily in the GIT and disseminate to involve lymph nodes or other extra-intestinal sites. Optimal work-up and treatment plan is not well established. Endoscopic evaluation of the entire GIT and whole body PET are required for accurate staging. Based on the stage, treatment options include watch and wait approach, surgery, chemotherapy, radiotherapy, immune-radiotherapy or a multi-modal approach. Chemotherapy with rCHOP was initiated on our patient. Initially he responded to the regimen. Unfortunately, the disease turned aggressive shortly afterwards, and he subsequently transitioned to palliative care.1935_A Figure 1. Capsule endoscopy demonstrating edema, erosion, luminal narrowing and oozing in distal jejunum/proximal ileum.1935_B Figure 2. Active oozing from the erythematous, inflamed area with luminal narrowing narrowing in the distal jejunum/proximal ileum noted on capsule endoscopy.1935_C Figure 3. Capsule endoscopy demonstrating edematous, inflamed area in distal jejunum

ESTIMATION OF THE ORGAN ABSORBED DOSES AND EFFECTIVE DOSE FROM 68Ga-PSMA-11 PET SCAN.

68Ga-PSMA-11 PET/CT has been proven to have high clinical value for imaging of prostate cancer and rapidly gained popularity. In this study, we aimed to investigate absorbed doses of 68Ga-PSMA-11. Seven patients (mean age = 66.9 ± 6.6 years, range: 57-79 years) were enrolled in the study. Whole body PET images were acquired with multiple time points. MIRD method, NUKFIT and OLINDA/EXM software were used for dosimetry calculations. Kidneys, bladder wall, salivary and lacrimal glands received the highest absorbed dose. Estimated absorbed doses to these organs after injection of 150 MBq 68Ga-PSMA-11 were 37.0, 12.6, 14.4 and 6.3 mSv, respectively. Effective dose from PET scanning with 150 MBq injected 68Ga-PSMA-11 was 2.5 mSv. In conclusion, 68Ga-PSMA-11 has a favorable dosimetry profile similar to the 68Ga labeled octreotide analogs, which are used safely in routine clinical practices for many years. No adverse effects were reported. The kidneys were the dose-limiting organs.

Massive enlargement of all peripheral nerves

A 29 year old woman presented with three months of intermittent but increasing bifacial paraesthesia. On close questioning she reported five years of mild intermittent paraesthesiae in both hands and very mild proximal upper limb weakness. Examination revealed a small area of pinprick loss over the left cheek as the only abnormality. Nerve conduction study of both upper limbs demonstrated symmetric distal sensory and motor abnormalities strongly suggestive of demyelination (small or absent sensory potentials and markedly prolonged distal motor latencies). The remainder of extensive neurophysiologic assessment was normal. MRI brain and whole spine revealed massive symmetric enlargement of multiple cranial nerves, nerve roots, brachial and lumbosacral plexuses (Fig. 1A–F), without contrast enhancement. CSF showed albuminocytologic dissociation (protein 1.48 g/L) and extensive blood tests and whole body PET scan were normal. The most likely diagnosis isA.SarcoidosisB.Charcot Marie Tooth (CMT)C.Chronic Inflammatory Demyelinating Polyradiculopathy (CIDP)D.Leprosy CIDP was diagnosed based on these neurophysiologic, CSF and MRI findings and intravenous immunoglobulin (ivIg) was eventually commenced due to increasing symptoms. One year following presentation the patient was largely asymptomatic on maintenance monthly ivIg, with significant improvement in neurophysiologic parameters but no change in MRI features. The striking feature of this case was the extreme discordance between a mild clinical presentation of CIDP and the MRI findings of widespread and massive hypertrophy of multiple cranial nerves, nerve roots and plexuses. This point is highlighted by noting that the dramatic lumbar root and plexus MRI abnormalities were associated with absolutely no symptoms, signs or neurophysiological abnormalities. Massive peripheral nerve enlargement has a relatively limited differential diagnosis. Congenital causes, such as Charcot-Marie-Tooth or Neurofibromatosis; and acquired pathology, in particular leparomatous disease or an infiltrative process such as systemic amyloidosis, seemed unlikely given demyelinating neurophysiology that was clearly reversible with ivIg. Massive nerve root thickening on MRI has been reported in inflammatory conditions. The most common of these being CIDP, but to our knowledge this is the first report of massive cranial nerve enlargement in the condition [1Duggins A.J. McLeod J.G. Pollard J.D. et al.Spinal root and plexus hypertrophy in chronic inflammatory demyelinating polyneuropathy.Brain. 1999; 122: 1383-1390Crossref PubMed Scopus (193) Google Scholar, 2Adachi Y. Sato N. Okamoto T. et al.Brachial and lumbar plexuses in chronic inflammatory demyelinating polyradiculoneuropathy: MRI assessment including apparent diffusion coefficient.Neuroradiology. 2010; 53 ([published Online First: Epub Date]): 3-11https://doi.org/10.1007/s00234-010-0684-7Crossref PubMed Scopus (69) Google Scholar, 3Shibuya K. Sugiyama A. S-i Ito et al.Reconstruction magnetic resonance neurography in chronic inflammatory demyelinating polyneuropathy.Ann Neurol. 2015; 77 ([published Online First: Epub Date]): 333-337https://doi.org/10.1002/ana.24314Crossref PubMed Scopus (85) Google Scholar]. The initial report correlated massive root hypertrophy with a long and disabling disease course [[1]Duggins A.J. McLeod J.G. Pollard J.D. et al.Spinal root and plexus hypertrophy in chronic inflammatory demyelinating polyneuropathy.Brain. 1999; 122: 1383-1390Crossref PubMed Scopus (193) Google Scholar]. However subsequent case series have not found any definite correlation between nerve hypertrophy and disease severity or duration [2Adachi Y. Sato N. Okamoto T. et al.Brachial and lumbar plexuses in chronic inflammatory demyelinating polyradiculoneuropathy: MRI assessment including apparent diffusion coefficient.Neuroradiology. 2010; 53 ([published Online First: Epub Date]): 3-11https://doi.org/10.1007/s00234-010-0684-7Crossref PubMed Scopus (69) Google Scholar, 3Shibuya K. Sugiyama A. S-i Ito et al.Reconstruction magnetic resonance neurography in chronic inflammatory demyelinating polyneuropathy.Ann Neurol. 2015; 77 ([published Online First: Epub Date]): 333-337https://doi.org/10.1002/ana.24314Crossref PubMed Scopus (85) Google Scholar]. It is possible that MRI features differ between the various subtypes of CIDP and focal demyelination on neurophysiological testing of peripheral nerves has been associated with focal reversible contrast enhancement [3Shibuya K. Sugiyama A. S-i Ito et al.Reconstruction magnetic resonance neurography in chronic inflammatory demyelinating polyneuropathy.Ann Neurol. 2015; 77 ([published Online First: Epub Date]): 333-337https://doi.org/10.1002/ana.24314Crossref PubMed Scopus (85) Google Scholar, 4Kuwabara S. Nakajima M. Matsuda S. Hattori T. Magnetic resonance imaging at the demyelinative foci in chronic inflammatory demyelinating polyneuropathy.Neurology. 1997; 48 ([published Online First: Epub Date]): 874-877https://doi.org/10.1212/wnl.48.4.874Crossref PubMed Google Scholar]. However in routine practice MRI abnormalities simply provide supportive evidence of CIDP without specific management implications. The remarkable findings in our case suggest that massive hypertrophy can occur with very mild clinical disease. We propose that recurrent or chronic subclinical inflammation, demyelination and repair can lead to massive hypertrophy, almost as an oyster lays down layers of a pearl. Dr Fong was involved in the management and care of the patient and preparation and drafting of the manuscript. No disclosures relevant to this study are reported. Dr Masters was involved in the management and care of the patient and preparation and drafting of the manuscript and figures. No disclosures relevant to this study are reported. Dr Watson was involved in the management and care of the patient and preparation and drafting of the manuscript. No disclosures relevant to this study are reported.

Abstracts of the Total Body PET conference 2018

Abstracts of the Total Body PET conference 2018

7. Papillary thyroid cancer in a patient with Morvan’s syndrome

Morvan’s syndrome is a rare disorder, characterized by peripheral nerve hyperexcitability, dysautonomia and encephalopathy with marked insomnia. About three quarters of patients have voltage gated potassium channel (VGKC) antibodies. A significant proportion of patients have associated tumours and the majority of these are thymomas. A 53 year-old man presented with a history of pain, cramps and twitching of the muscles of the chest and limbs, insomnia, hyperhidrosis, hypersalivation and cognitive impairment with hallucinations. Examination revealed fasciculations of the proximal upper limbs, piloerection of the forearms and mild postural hypotension. The patient underwent a number of electrophysiological studies: (1) EMG demonstrated spontaneous and frequent irregularly occurring neuromyotonic activity as doublet, triplet and multiplet single motor unit discharges firing at a high intraburst frequency (133–200 Hz), consistent with peripheral nerve hyperexcitability. (2) Paired-pulse transcranial magnetic stimulation revealed reduction in the short-interval intracortical inhibition (SICI) suggestive of central hyperexcitability. (3) EEG demonstrated left temporal slowing on an otherwise normal background. (4) autonomic testing showed a generalized sudomotor impairment consistent with autonomic dysfunction. Neuroimaging of the brain with PET demonstrated bilateral temporal lobe hypometabolism. Whole body PET revealed a hypermetabolic thyroid lesion, which was subsequently confirmed histologically to be a multifocal papillary thyroid carcinoma. The clinical and electrophysiological presentation was consistent with a diagnosis of Morvan’s syndrome in the context of a paraneoplastic phenomenon secondary to papillary thyroid cancer. The patient underwent a thyroidectomy and adjuvant radiotherapy. In addition, monthly intravenous methylprednisolone and intravenous immunoglobulin was instituted. Subsequently, the patient experienced significant symptomatic improvement with resolution of muscle fasciculations and cramps, hyperhidrosis and visual hallucinations. Insomnia and pain although improved did not completely resolve. This case reviews the clinical and neurophysiological findings of Morvan’s syndrome. The case adds to the small number of non-thymomatous tumours associated with this syndrome and highlights the importance of a thorough search for malignancy in this clinical context.

Advanced PET imaging in oncology: status and developments with current and future relevance to lung cancer care.

This review highlights the status and developments of PET imaging in oncology, with particular emphasis on lung cancer. We discuss the significance of PET for diagnosis, staging, decision-making, monitoring of treatment response, and drug development. The PET key advantage, the noninvasive assessment of functional and molecular tumor characteristics including tumor heterogeneity, as well as PET trends relevant to cancer care are exemplified. Advances of PET and radiotracer technology are encouraging for multiple fields of oncological research and clinical application, including in-depth assessment of PET images by texture analysis (radiomics). Whole body PET imaging and novel PET tracers allow assessing characteristics of most types of cancer. However, only few PET tracers in addition to F-fluorodeoxyglucose have sufficiently been validated, approved, and are reimbursed for a limited number of indications. Therefore, validation and standardization of PET parameters including tracer dosage, image acquisition, post processing, and reading are required to expand PET imaging as clinically applicable approach. Considering the potential of PET imaging for precision medicine and drug development in lung and other types of cancer, increasing efforts are warranted to standardize PET technology and to provide evidence for PET imaging as a guiding biomarker in nearly all areas of cancer treatment.