Vertebral photopenia on [67Ga]Ga-citrate and [18F]FDG PET/CT imaging in a patient with non-Hodgkin lymphoma.

A cold vertebral defect is an uncommon finding, especially in Gallium-67-citrate ([67Ga]Ga-citrate) - and [18F]fluorodeoxyglucose ([18F]FDG) - avid lymphomas, representing a diagnostic challenge. Here, we present the case of a patient with non-Hodgkin lymphoma (NHL), in whom the [67Ga]Ga-citrate and [18F]FDG scans showed a diffuse skeletal uptake pattern with concomitant appearance of a cold vertebral defect. Awareness of the different causes of such uptake patterns and accurate clinical information is important to avoid misinterpretation of nuclear studies in oncologic patients.

Cholethorax with biliopleural communication detected on [99mTc]mebrofenin hepatobiliary scintigraphy.

Bilious pleural effusion or cholethorax is a rare type of exudative pleural effusion. Here is presented a case of right-sided cholethorax, in which the direct communication between the pleural effusion with the biliary duct was visible only on the posteriori images of dynamic hepatobiliary scintigraphy with [99mTc]mebrofenin.

A Bayesian look at the new 2019 guidelines for imaging of pheochromocytoma/paraganglioma with emphasis on extra-adrenal disease.

Dear Editor, In this journal, a few years ago, we presented a Bayesian (critical) appraisal of the-then recent-American Endocrine Society's guidelines regarding the diagnosis and management of pheochromocytoma/paraganglioma (PPG). This year, the European Society of Nuclear Medicine and the Society of Nuclear Medicine and Molecular Imaging have introduced new guidelines regarding functional imaging (i.e. by means of Nuclear Medicine modalities) of PPG. In light of this, we believe that it is appropriate to present a new relevant Bayesian assessment. In the new guidelines the following functional imaging modalities are covered: iodine-123-metaiodobenzylguanidine (123I-MIBG) single photon emission tomography (SPET), indium-111-diethylenetriamine pentaacetic acid (111In-DTPA)-pentetreotide (111In-pentetreotide) SPET, fluorine-18-fluorodihydroxyphenylalanine (18F-FDOPA) positron emission tomography (PET), 18F-fluorodeoxyglucose (18F-FDG) PET and PET with various gallium-68-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (168Ga-DOTA)-coupled somatostatin agonists (68Ga-SSTa). Based on a pretest probability of 15% for extra-adrenal disease and the reported sensitivity and specificity for each modality, we calculated likelihood ratios (LR) for a positive and a negative test (LR+ and LR-, respectively). In the absence of a given specificity in the guidelines we used levels of 55% for 18F-FDG and 85% for 68Ga-SSTa (the latter is a level that we used in our previous assessment), which have been validated in a recent meta-analysis. Using LR+ and LR- with Fagan's nomograms we calculated the post-test probability of extra-adrenal PPG. Only the LR+ for 18F-FDOPA was over 10 and no LR- was lower than 0.1, shifting to an important degree the probability of a diagnosis (clinicians have to bear in mind that an LR- may not be useful, since absence of radionuclide uptake does not imply absence of PPG if biochemistry is positive). It is evident that functional imaging of PPG has become more diversified and tailored according to each patient's history and genetic background. Nevertheless, the diagnostic characteristics of all methods (biochemical and imaging) are still not perfect; they are rather complimentary to each other. Biochemical evaluation should be done first, since functional imaging of PPG is advised to be performed in patients with biochemically-proven disease.

Is There Seasonality in Hypothyroidism? A Google Trends Pilot Study.

INTRODUCTION: There may be seasonality in thyroid diseases and internet search data may provide information on disease patterns. In this study we used data from internet searches on hypothyroidism to assess seasonality in this disease. METHODS: We collected worldwide data, as well as data for countries in the southern hemisphere (Brazil, South Africa, and Australia), covering 15 years, from Google Trends with the search term "hypothyroidism+thyroiditis (the commonest cause of hypothyroidism)" and "fatigue+weakness (the commonest symptoms of hypothyroidism)". We looked for periodicity in relevant internet searches by calculating autocorrelations; we also looked at the cross-correlation of internet searches for "hypothyroidism+thyroiditis" and "fatigue+weakness" and we compared the results by season with the Kruskall-Wallis test. RESULTS: There was periodicity in the relevant internet searches and strong cross-correlations between internet searches for "hypothyroidism+thyroiditis" and "fatigue+weakness" worldwide and for South Africa and Australia. In both the northern and the southern hemispheres there were significantly more hypothyroidism-related internet searches during spring (p<0.05). CONCLUSION: Hypothyroidism was more popular in internet searches at springtime in the northern and the southern hemispheres. Thus, although this analysis is coarse, it seems that some seasonality can be inferred on hypothyroidism, taking into account the limitations of our approach.

Functional Imaging of Paragangliomas with an Emphasis on Von Hippel-Lindau-Associated Disease: A Mini Review.

Few reports have presented data and results on functional (i.e., nuclear medicine) imaging of paragangliomas and pheochromocytomas (PGLs/PHEOs) for von Hippel-Lindau (VHL) patients. Nuclear medicine localization modalities for chromaffin tumors can be specific or nonspecific. Specific methods make use of the expression of the human norepinephrine transporter (hNET) and vesicular monoamine transporters (VMATs) by these tumors. These permit the use of radiolabeled ligands that enter the synthesis and storage pathway of catecholamines. Nonspecific methods are not related to the synthesis, uptake, or storage of catecholamines but make use of the tumors' high glucose metabolism or expression of somatostatin receptors. Consensuses and guidelines suggest that metastatic and sporadic PHEOs/PGLs in VHL patients (as in patients with chromaffin tumors of yet unknown genotype) should be evaluated first with 18F-dihydroxyphenylalanine (18F-DOPA) positron emission tomography/computed tomography (PET/CT). The functional imaging of second choice is 123I-metaiodobenzylguanidine (123I-MIBG) for PHEOs in VHL patients. 123I-MIBG, 68Ga-DOTATATE/DOTATOC/DOTANOC PET/CT, or 18F-fluorodeoxyglucose (18F-FDG) PET/CT can be a second choice of functional imaging for PGLs in VHL patients.

The diagnostic performance of (99m)Tc-HMPAO radiolabeled leucocytes scintigraphy in the investigations of infection. A single center experience.

OBJECTIVE: This study aims to evaluate the diagnostic efficacy of (99m)Tc-HMPAO-labeled white blood cells scintigraphy (RL-WBC scan) in a variety of infectious processes. Despite the technical difficulties of labeling WBCs without altering their viability/pathophysiologic integrity and the lengthy imaging procedure, the RL-WBC scan has gained an evolving role in the detection of occult infection. METHODS: Retrospective review of 66 patient files (34 males and 32 females) that underwent this functional imaging test from September 2013 until September 2015. Their mean age was 58.39±18.63 (range: 11-84) years. Twenty seven of them were investigated for fever of unknown origin, 6 with suspicion of inflammatory bowel disease, 9 with aneurysm of celiac artery before or after abdominal endovascular aortic repair, 6 with joint prostheses, 5 with diabetic angiopathy, and 13 had rather undefined symptoms. RESULTS: The mean labeling yield of the leukocytes with the lipophilic complex (99m)Tc-HMPAO was 57.4±8.6. The RL-WBC scan was positive in 39/66 patients, including 16/27 patients with fever of unknown origin and 8/9 patients with aortic aneurysm/graft infection. It showed expected/suspected localization of radioactivity in 23 patients, whereas 11 of them had equivocal signs of infection. In 16 patients, a significant change in patients' management was conferred, as non-suspected locations of inflammatory process were detected, based on early functional alterations derived from leukocyte recruitment. CONCLUSION: The RL-WBC scan (i) is extremely useful in the diagnosis of perigraft tissue infection and osteomyelitis (except for spine) with high rate of sensitivity and specificity (≈90%) when timely used, and (ii) may provide valuable information in patients with fever of unknown origin, inflammatory bowel disease or vague symptoms. False positive results have been noticed mainly due to artifacts, co-existent skeletal lesions or in the early postoperative course because of the nonspecific radionuclide uptake in the healing tissue. On the other hand, false negative results may appear in delayed aortic graft infection, etc. Difficulties arise in the discrimination between infection and sterile inflammatory lesions accompanying atheromatosis or grafts/prostheses. Our experience shows that there should take place a closer co-operation between nuclear medicine physicians and clinicians to ensure the rational selection of the patients that would benefit from this complex diagnostic procedure, in order to get the optimal results concerning in vivo inflammation/abscess visualization.

A probabilistic assessment of the diagnosis of paraganglioma/pheochromocytoma based on clinical criteria and biochemical/imaging findings.

UNLABELLED: Paragangliomas (PGL) and pheochromocytomas (P) are rare neural-crest-derived neoplasms. Very recently guidelines on diagnosis and treatment of PGL/P have been presented by the US Endocrine Society. In the following overview we assessed the implementation of these guidelines with probabilistic reasoning (calculating with Fagan nomograms the post-test probability of PGL/P for a given pre-test probability). CONCLUSION: Biochemical evaluation of PGL/P showed excellent diagnostic characteristics with post-test probabilities that are very different from the pre-test probabilities, thus a positive biochemical test is usually indicative of disease whereas a negative one usually rules out disease. The post-test probabilities of anatomical and functional imaging modalities (i.e. in nuclear medicine) were different from the pre-test probabilities but to a lesser degree than the biochemical tests; furthermore in biochemically-proven PGL/P a negative imaging modality is not useful, while a positive one may indicate only one of multiple foci of metastatic/extra-adrenal disease. Thus, regarding imaging modalities, they should be combined in order to get the most of their characteristics for the localization of PGL/P.