Search

The role of magnetism in the biological functioning of hemoglobin has been debated since its discovery by Pauling and Coryell in 1936. The hemoglobin molecule contains four heme groups each having a porphyrin layer with a Fe ion at the center. Here, we present combined density-functional theory and quantum Monte Carlo calculations for an effective model of Fe in a heme cluster. In comparison with these calculations, we analyze the experimental data on human adult hemoglobin (HbA) from the magnetic susceptibility, Mössbauer and magnetic circular dichroism (MCD) measurements. In both the deoxygenated (deoxy) and the oxygenated (oxy) cases, we show that local magnetic moments develop in the porphyrin layer with antiferromagnetic coupling to the Fe moment. Our calculations reproduce the magnetic susceptibility measurements on deoxy and oxy-HbA. For deoxy-HbA, we show that the anomalous MCD signal in the UV region is an experimental evidence for the presence of antiferromagnetic Fe-porphyrin correlations. The functional properties of hemoglobin such as the binding of O 2 , the Bohr effect and the cooperativity are explained based on the magnetic correlations. This analysis suggests that magnetism could be involved in the functioning of hemoglobin.

Objective: Primary hyperparathyroidism (PHPT) is a common endocrine disease that is caused by a single adenoma in most of the cases. Surgical management is the mainstay and definitive treatment for parathyroid adenoma (PA). Minimally invasive surgical techniques are as effective as bilateral neck exploration with a lower risk of complications and better cosmetic results in patients with solitary PA. Accurate preoperative localization with imaging modalities is paramount for determining patients candidate for minimally invasive surgery. In this study we aimed to evaluate the diagnostic performance of technetium-99m-methoxyisobutylisonitrile ( 99m Tc-MIBI) planar scintigraphy (PS), single photon emission tomography/computed tomography (SPET/CT) and ultrasonography (US) in patients with PHPT., Material and Methods: Fifty-eight patients with biochemical evidence of PHPT who underwent pre-operative imaging with parathyroid scintigraphy and US for detection and localization of PA and proceeded to surgery were included in the study. All patients underwent dual phase 99m Tc-sesta MIBI parathyroid scintigraphy (early and delayed planar images and delayed SPET/CT). Data analysis was performed to evaluate the sensitivity, specificity, diagnostic accuracy and PPV of planar images, SPET/CT and US alone and combined US and SPET/CT. Histopathology was used as gold standard., Results: Sensitivity, specificity, PPV and diagnostic accuracy for detection of PA, 80,4%, 42,8%, 91,1% and 75,8% for PS; 80,4%, 57,7%, 91,1% and 77,5% for delayed SPET/CT; 88,2%, 85,7%, 97,8% and 87,9% for US and 94,1%, 71,4%, 96% and 91,3% for SPET/CT+US. Combined US and SPET/CT has been shown to increase sensitivity and diagnostic accuracy. The overall sensitivity of PS and SPET/CT didn't vary however additional information which is helpful for planning minimally invasive surgery gained from tomographic images., Conclusion: The combined use of US and SPET/CT has incremental value in accurately localizing PA over either technique alone. In the preoperative assessment of patients with PHPT combination of imaging methods allows selection of patients who would be suitable for minimally invasive surgery.

The aim of this study was to investigate the prognostic significance of standardized uptake value (SUV) on 18 fluorine-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography/computed tomography (PET/CT) in patients with nasopharyngeal carcinoma (NPC). Thirty-four patients who have histologically proven NPC and underwent 18 F-FDG PET/CT were included in this study. After 18 F-FDG PET/CT, all the patients received radiation therapy and 32 of them received concomitant weekly chemotherapy. The maximum SUV (SUV max ) at the primary tumor and the SUV max of the highest neck nodes were determined. The SUV max -T ranged from 5.00 to 30.80 (mean: 15.37 ± 6.10) and there was no difference between SUV max -T values for early and late stages ( P = 0.99). The SUV max -N ranged from 3.10 to 23.80 (mean: 13.23 ± 5.76). There was no correlation between SUV max -T and SUV max -N ( r = 0.111, P = 0.532). There was no difference between the SUV max -T and the positivity of neck lymph nodes ( P = 0.169). The ability of SUV maks -N to predict stage was obtained by a receiver operating characteristic (ROC) analysis. The area under the curve is 0.856 and the best cut-off value is 7.88. There was a good correlation between SUV max -N and stage. While the mean SUV max -T for the alive patients was slightly lower than that for the dead (14.65 ± 5.58 vs. 20.30 ± 7.92, P = 0.061), the difference between the groups was not statistically significant. Furthermore, there was no statistically significant difference for SUV max -N between these two groups (P: 0.494). Cox-regression analysis showed that an increase in SUV max -T and SUV max -N was associated with death risk (relative risk [RR]: 1.13, P = 0.078 and RR: 1.052, P = 0.456, respectively). SUV max -T and SUV max -N were independent prognostic factors for survival in NPC patients. This will help the clinicians in choosing suitable candidates for more aggressive treatment modalities., Competing Interests: There are no conflicts of interest.

Objective: When a scintigraphically autonomous nodule does not produce thyroid hormones enough to suppress serum thyrotrophin, it is generally defined as nontoxic autonomous nodule. In this study, we aimed to compare clinical and ultrasonographical (US) features and cytological and histopathological results of toxic and nontoxic autonomous nodules., Methods: Patients who underwent thyroidectomy and were evaluated with technetium-99m-pertechnetate scintigraphy preoperatively in our institution between May 2008 and December 2014 were identified from medical records. Among these, treatment naïve patients with scintigraphically autonomous thyroid nodules were chosen and classified into toxic (hyperthyroid) and nontoxic (euthyroid) groups. The demographic data, preoperative US features of the nodules, fine needle aspiration biopsy and histopathological results were analyzed., Results: There were 170 (89.0%) patients with toxic and 21 (11.0%) patients with nontoxic autonomous nodules. A total of 258 scintigraphically autonomous nodules were analyzed among which 227 were clinically functional (toxic) and 31 were clinically euthyroid (nontoxic). Echogenity, texture, marginal irregularity, presence of halo and macrocalcification were similar in toxic and nontoxic autonomous nodules. Toxic autonomous nodules were significantly bigger and had a significantly higher rate of microcalcification compared to nontoxic ones (p = 0.001 and p = 0.025, respectively). There was no significant difference in terms of cytological diagnosis between toxic and nontoxic autonomous nodules (p = 0.052). Atypia of undetermined significance/follicular lesion of undetermined significance cytology was significantly higher in nontoxic group (p = 0.01). 20 (8.8%) of 227 toxic and 2 (6.5%) of 31 nontoxic autonomous nodules were malignant (p = 0.59). Considering all nodules regardless of the thyroid function, 8.5% of autonomous nodules was malignant., Conclusion: US features and malignancy potential of nontoxic autonomous nodules resemble toxic autonomous nodules. Lower diameter suggests that they can represent a preliminary stage of toxic ones and have potential of toxicity when get bigger in size. There is still a considerable risk of malignancy risk in autonomous nodules whether toxic or not.

Background/aim: We aimed to define the optimal SUV(max) cut-off value in determination of mediastinal-hilar lymph node metastasis, by comparing positive PET/CT results with the results of endobronchial ultrasound guided transbronchial needle aspiration biopsy (EBUS-TBNA)., Materials and Methods: Thirty-one patients with malignancy whose PET/CT imaging revealed a hypermetabolic mediastinal and/or hilar lymph node and who had undergone EBUS-TBNA were evaluated retrospectively. Histopathology was regarded as the gold standard. The diagnostic role of PET/CT in mediastinal/hilar lymph node metastasis was investigated and compared with the results of contrast-enhanced CT., Results: When a SUV(max) value of 2.5 was used, the sensitivity, positive predictive value (PPV), and diagnostic accuracy of the PET/CT were 100%, 65.4%, and 65.4% respectively. In the ROC analysis, the SUV(max) cut-off value with the highest diagnostic accuracy (75%) was calculated as 6.3, and when this value was considered, the sensitivity, specificity, PPV, negative predictive value, and diagnostic accuracy of the PET/CT were determined as 70.6%, 83.3%, 88.9%, 60%, and 75% respectively (AUC: 0.779). The sensitivity, PPV, and diagnostic accuracy of the thorax CT were calculated as 91.1%, 72%, and 71.1%, respectively., Conclusion: When determining mediastinal-hilar lymph node metastasis via PET/CT, although a SUV(max) cut-off value of 6.3 increases specificity and diagnostic accuracy, we think that a SUV(max) cut-off value of 2.5 and above give more optimal results in routine practice.

Objective: The aim of this study was to investigate the relationship between patient characteristics and adenosine-related side-effects during stress myocard perfusion imaging (MPI). The effect of presence of adenosine-related side-effects on the diagnostic value of MPI with integrated SPECT/CT system for coronary artery disease (CAD), was also assessed in this study., Methods: Total of 281 patients (109 M, 172 F; mean age:62.6±10) who underwent standard adenosine stress protocol for MPI, were included in this study. All symptoms during adenosine infusion were scored according to the severity and duration. For the estimation of diagnostic value of adenosine MPI with integrated SPECT/CT system, coronary angiography (CAG) or clinical follow-up were used as gold standard., Results: Total of 173 patients (61.6%) experienced adenosine-related side-effects (group 1); flushing, dyspnea, and chest pain were the most common. Other 108 patients completed pharmacologic stress (PS) test without any side-effects (group 2). Test tolerability were similar in the patients with cardiovascular or airway disease to others, however dyspnea were observed significantly more common in patients with mild airway disease. Body mass index (BMI) ≥30 kg/m2 and age ≤45 years were independent predictors of side-effects. The diagnostic value of MPI was similar in both groups. Sensitivity of adenosine MPI SPECT/CT was calculated to be 86%, specificity was 94% and diagnostic accuracy was 92% for diagnosis of CAD., Conclusion: Adenosine MPI is a feasible and well tolerated method in patients who are not suitable for exercise stress test as well as patients with cardiopulmonary disease. However age ≤45 years and BMI ≥30 kg/m2 are the positive predictors of adenosine-related side-effects, the diagnostic value of adenosine MPI SPECT/CT is not affected by the presence of adenosine related side-effects.

F-18-fluorodeoxyglucose (FDG) positron emission tomography/CT is an important whole-body imaging tool in the oncology and widely utilized to stage and restage various malignancies. The findings of significant focal accumulation of FDG in the lung parenchyma in the absence of corresponding CT abnormalities are related to the lung microembolism and known as hot-clot artifacts. Herein we present two cases with focal FDG uptake in the lung parenchyma with no structural lesions on the CT scan and discuss the possible mechanisms.

Although mucocutaneous sites are the most frequently encountered sites of involvement, Kaposi Sarcoma (KS) may also occasionally involve the breast and the skeletal, endocrine, urinary and nervous systems.. Various imaging modalities may be used to delineate the extent of the disease by detecting unexpected sites of involvement. Herein, we report a case of classical type KS, in whom staging with (18)F-FDG PET/CT imaging disclosed widespread disease and unexpected findings of bone and salivary gland involvement., (Copyright © 2013 Elsevier España, S.L. and SEMNIM. All rights reserved.)

Whole body radioiodine scanning (WBS), along with plasma thyroglobulin level, remains a reference method for detecting residual or metastatic differentiated thyroid cancer, however, false-positive WBS is not uncommon. External contaminations by body secretions or excretions, inflammation, and cystic structures mimicking metastases in WBS have been reported. Various benign and malignant tumors having different histopathological natures accumulate radioiodine, but intradermal melanocytic nevus was not previously described in the literature, as far as we know. This report describes an unusual cause of false-positive WBS after radioablation therapy due to an intradermal nevus, and the possible mechanisms are discussed.