18F‐Fluorodeoxyglucose (FDG)‐PET features of focal nodular hyperplasia (FNH) of the liver

Abstract: Aim: The aim of this paper is to describe the imaging pattern of focal nodular hyperplasia (FNH) by ¹⁸F‐fluorodeoxyglucose (18F‐FDG) positron emission tomography (PET). Methods: Eight consecutive asymptomatic patients with histologic proof of FNH underwent 18F‐FDG PET imaging. The lesions were found incidentally. The 18F‐FDG PET imaging was performed with a dedicated PET tomograph after intravenous injection of 300–370 MBq 18F‐FDG. The 18F‐FDG accumulation in the lesions was (semi)quantified by calculating the standardized uptake value (SUV) and SUV has been corrected for the lean body mass (LBM). Eight patients with liver metastases spread from melanoma (n=2) and colorectal carcinoma (n=6) served as controls. The size of the FNH lesions and of the control group ranged from 2.0 to 8.5 cm (mean 4.83 cm±2.37) and from 1.5 to 6 cm (mean 3.28±1.52), respectively. Results: While in malignant liver lesions the accumulation of 18F‐FDG was significantly increased, all FNH lesions showed normal or even decreased accumulation of 18F‐FDG. In FNH lesions, SUV ranged between 1.5 and 2.6 (mean 2.12±0.38), whereas all liver metastases showed an increased SUV ranging between 6.20 and 16.00 (mean 10.07±3.79). The SUV corrected for LMB (SUV_LBM) was similar to the SUV and ranged between 0.9 and 2.2 (mean 1.81±0.41) for FNH and between 5.9 and 16.3 (mean 9.15±4.03), respectively. Conclusion: In contrast to liver metastases, there is no increased glucose metabolism in FNH in vivo. The imaging feature of FNH by 18F‐FDG‐PET imaging is not specific for FNH; however, it may be helpful to differentiate FNH from liver metastases in cancer patients if radiological methods are not diagnostic.     

Current knowledge on the sensitivity of the <Superscript>68</Superscript>Ga-somatostatin receptor positron emission tomography and the SUV<Subscript>max</Subscript> reference range for management of pancreatic neuroendocrine tumours

Physiologically increased pancreatic uptake at the head/uncinate process is observed in more than one-third of patients after injection of one of the three ⁶⁸Ga-labelled octreotide-based peptides used for somatostatin (sst) receptor (r) imaging. There are minor differences between these ⁶⁸Ga-sstr-binding peptides in the imaging setting. On ⁶⁸Ga-sstr-imaging the physiological uptake can be diffuse or focal and usually remains stable over time. Differences in the maximal standardised uptake values (SUV_max) reported for the normal pancreas as well as for pancreatic neuroendocrine tumour (PNET) lesions may be related to several factors, including (a) differences in the peptide binding affinities as well as differences in sstr subtype expression of pancreatic α- and β-cells, and heterogeneity / density of tumour cells, (b) differences in scanner resolution, image reconstruction techniques and acquisition protocols, (c) mostly retrospective study designs, (d) mixed patient populations, or (e) interference with medications such as treatment with long-acting sst analogues. The major limitation in most of the studies lies in the lack of histopathological confirmation of abnormal findings. There is a significant overlap between the calculated SUV_max-values for physiological pancreas and PNET-lesions of the head/uncinate process that do not favour the use of quantitative parameters in the clinical setting. Anecdotal long-term follow-up studies have even indicated that increased uptake in the head/uncinate process still can turn out to be malignant over years of follow up. SUV_max-data for the pancreatic body and tail are limited. Therefore, any visible focal tracer uptake in the pancreas must be considered as suspicious for malignancy irrespective of quantitative parameters. In general, sstr-PET/CT has significant implications for the management of NET patients leading to a change in treatment decision in about one-third of patients. Therefore, follow-up with ⁶⁸Ga-sstr-PET/CT is mandatory in the clinical setting if uptake in the head/uncinate process is observed.     

123I-tyrosine-(A14)-insulin: preparation and preliminary clinical studies.

Insulin was radioiodinated with 123I (123I-tyrosine-(A14)-insulin) to a specific activity of 1 micrograms/mCi, corresponding to 0.025 I.U. of insulin/mCi. This preparation was used for in vitro binding experiments with adipose tissue, showing active binding to the two subunits of the known insulin receptor. In a preliminary clinical investigation, 5 adipose patients with (n = 2) and without (n = 3) diabetes mellitus Type II, were subject to in vivo injection of the same radiolabeled product using 3 mCi/patient. During the first minutes of dynamic imaging, the liver was the major organ of tracer uptake in all patients. Furthermore, the pancreas, and in one patient the kidneys, were visualised. Further studies on insulin in vivo kinetics and quantification are under way.     

Cardiac sympathetic innervation in Parkinson’s disease versus multiple system atrophy

Purpose

The aims of this study were to evaluate the diagnostic accuracy of the dual imaging method combining cardiac iodine-¹²³-metaiodobenzylguanidine single-photon emission computed tomography combined with low-dose chest computed tomography compared to routine cardiac scintigraphy, and assess regional differences in tracer distribution and the relationships between imaging and autonomic function in Parkinson’s disease and multiple system atrophy.

Methods

A prospective study including 19 Parkinson’s disease and 12 multiple system atrophy patients was performed. Patients underwent clinical evaluation, iodine-¹²³-metaiodobenzylguanidine single-photon emission computed tomography combined with chest computed tomography, planar scintigraphy, and cardiovascular autonomic function tests.

Results

Co-registration of single-photon emission computed tomography and chest computed tomography resulted in three groups with distinct patterns of tracer uptake: homogeneous, non-homogeneously reduced and absent. There was a significant difference in group allocation among patients with multiple system atrophy and Parkinson’s disease (p?=?0.001). Most multiple system atrophy patients showed homogeneous uptake, and the majority of Parkinson’s disease patients showed absent cardiac tracer uptake. We identified a pattern of heterogeneous cardiac tracer uptake in both diseases with reductions in the apex and the lateral myocardial wall. Sympathetic dysfunction reflected by a missing blood pressure overshoot during Valsalva manoeuvre correlated with cardiac tracer distribution in Parkinson’s disease patients (p?<?0.001).

Conclusions

The diagnostic accuracy of the dual imaging method and routine cardiac scintigraphy were similar. Anatomical tracer allocation provided by the dual imaging method of cardiac iodine-¹²³-metaiodobenzylguanidine single-photon emission computed tomography and chest computed tomography identified a heterogeneous subgroup of Parkinson’s disease and multiple system atrophy patients with reduced cardiac tracer uptake in the apex and the lateral wall. Sympathetic dysfunction correlated with cardiac imaging in Parkinson’s disease patients.

     

The economic impact of smoke-free laws on sales in bars and restaurants in Argentina

We studied the impact of the recent smoke-free laws on the sales in bars and restaurants, in the city of Buenos Aires and in three provinces of Argentina. Using a quasi-experimental design and a difference-in-differences estimation procedure we found that the smoke-free laws did not have a statistically significant negative effect on sales in bars and restaurants in the city of Buenos Aires and in the provinces of Córdoba, Santa Fe and Tucumán. Moreover, in the case of Buenos Aires, the smoke-free legislation could have induced an increase in the sales in bars and restaurants.     

Do passive smokers have an increased risk of thrombosis?

In contrast to the proven association between active smoking and vascular injury, as well as hemostatic imbalance, such a relation is not jet proven for passive smoking. Vascular damage induced by smoking, however, can be seen in the materno-fetal circulation of smoking mothers, being much more pronounced in the umbilical system than in fetal vessels. These lesions show fast recovery after birth. In non-smokers acute exposure to passive smoke induces a short-lasting activation of platelet function and the prostaglandin system, followed by a quick recovery. Chronic exposure of non-smokers to passive smoke, however, results in changes of these parameters comparable to those seen in smokers, characterized by an activation of platelet function and a decrease in platelet sensitivity to the antiaggregatory prostaglandin I2. These results suggest that in non-smokers with atherogenic risk factors passive smoking may contribute to the incidence of atherosclerosis, as well as acute complications (thrombosis).