Strain-stabilized superconductivity.

Superconductivity is among the most fascinating and well-studied quantum states of matter. Despite over 100 years of research, a detailed understanding of how features of the normal-state electronic structure determine superconducting properties has remained elusive. For instance, the ability to deterministically enhance the superconducting transition temperature by design, rather than by serendipity, has been a long sought-after goal in condensed matter physics and materials science, but achieving this objective may require new tools, techniques and approaches. Here, we report the transmutation of a normal metal into a superconductor through the application of epitaxial strain. We demonstrate that synthesizing RuO2 thin films on (110)-oriented TiO2 substrates enhances the density of states near the Fermi level, which stabilizes superconductivity under strain, and suggests that a promising strategy to create new transition-metal superconductors is to apply judiciously chosen anisotropic strains that redistribute carriers within the low-energy manifold of d orbitals.

Subterahertz Momentum Drag and Violation of Matthiessen's Rule in an Ultraclean Ferromagnetic SrRuO_{3} Metallic Thin Film.

SrRuO_{3}, a ferromagnet with an approximately 160 K Curie temperature, exhibits a T^{2}-dependent dc resistivity below ≈30 K. Nevertheless, previous optical studies in the infrared and terahertz range show non-Drude dynamics at low temperatures, which seem to contradict Fermi-liquid predictions. In this work, we measure the low-frequency THz range response of thin films with residual resistivity ratios, ρ_{300K}/ρ_{4K}≈74. At temperatures below 30 K, we find both a sharp zero frequency mode which has a width narrower than k_{B}T/ℏ as well as a broader zero frequency Lorentzian that has at least an order of magnitude larger scattering. Both features have temperature dependences consistent with a Fermi liquid with the wider feature explicitly showing a T^{2} scaling. Above 30 K, there is a crossover to a regime described by a single Drude peak that we believe arises from strong interband electron-electron scattering. Such two channel Drude transport sheds light on reports of the violation of Matthiessen's rule and extreme sensitivity to disorder in metallic ruthenates.

Predictive Value of Asphericity in Pretherapeutic [111In]DTPA-Octreotide SPECT/CT for Response to Peptide Receptor Radionuclide Therapy with [177Lu]DOTATATE.

PURPOSE: The purpose of this study was to assess the value of the spatial heterogeneity of somatostatin receptor (SSR) volume, quantified as asphericity (ASP), and to predict response to peptide receptor radionuclide therapy (PRRT) in patients with metastatic gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN). PROCEDURES: From June 2011 to May 2013, patients suffering from GEP-NEN who underwent pretherapeutic [111In-DTPA0]octreotide scintigraphy (Octreoscan®) prior to [177Lu-DOTA0-Tyr3]octreotate ([177Lu]DOTATATE)-PRRT were enrolled in this retrospective evaluation. SSR expression in 20 NEN patients was qualitatively and quantitatively assessed using the Krenning score, the metastasis to liver uptake ratio (M/L ratio), and ASP at baseline. Response to PRRT was evaluated based on lesions, which were classified as responding lesions (RL) and non-responding lesions (NRL) after 4- and 12-month follow-ups. The values of the Krenning score, M/L ratio, and ASP for response prediction were compared by using the Mann-Whitney U test, Kruskal-Wallis test, and receiver operating characteristic (ROC) curves. RESULTS: Seventy-seven metastases (liver, n = 40; lymph node, n = 24; bone, n = 11; pancreas, n = 2) showed SSR expression. A higher ASP level was significantly associated with poorer response at both time points. ROC analyses revealed the highest area under the curve (AUC) for discrimination between RL and NRL for ASP after 4 months (AUC 0.97; p = 0.019) and after 12 months (AUC 0.96; p < 0.001), followed by the Krenning score (AUC 0.74; p = 0.082 and AUC 0.85; p < 0.001, respectively) and M/L ratio (AUC 0.77; p = 0.107 and AUC 0.82; p < 0.001). The optimal cutoff value for ASP was 5.12 % (sensitivity, 90 %; specificity, 93 %). CONCLUSION: Asphericity of SSR-expressing lesions in pretherapeutic single-photon emission computed tomography with integrated computed tomography (SPECT/CT) is a promising parameter for predicting response to PRRT in gastroenteropancreatic neuroendocrine neoplasms.

Adenosine plasma level correlates with homocysteine and uric acid concentrations in patients with coronary artery disease.

The role of hyperhomocysteinemia in coronary artery disease (CAD) patients remains unclear. The present study evaluated the relationship between homocysteine (HCys), adenosine plasma concentration (APC), plasma uric acid, and CAD severity evaluated using the SYNTAX score. We also evaluated in vitro the influence of adenosine on HCys production by hepatoma cultured cells (HuH7). Seventy-eight patients (mean age ± SD: 66.3 ± 11.3; mean SYNTAX score: 19.9 ± 12.3) and 30 healthy subjects (mean age: 61 ± 13) were included. We incubated HuH7 cells with increasing concentrations of adenosine and addressed the effect on HCys level in cell culture supernatant. Patients vs. controls had higher APC (0.82 ± 0.5 µmol/L vs 0.53 ± 0.14 µmol/L; p < 0.01), HCys (15 ± 7.6 µmol/L vs 6.8 ± 3 µmol/L, p < 0.0001), and uric acid (242.6 ± 97 vs 202 ± 59, p < 0.05) levels. APC was correlated with HCys and uric acid concentrations in patients (Pearson's R = 0.65 and 0.52; p < 0.0001, respectively). The SYNTAX score was correlated with HCys concentration. Adenosine induced a time- and dose-dependent increase in HCys in cell culture. Our data suggest that high APC is associated with HCys and uric acid concentrations in CAD patients. Whether the increased APC participates in atherosclerosis or, conversely, is part of a protective regulation process needs further investigations.

Interplay of spin-orbit interactions, dimensionality, and octahedral rotations in semimetallic SrIrO(3).

We employ reactive molecular-beam epitaxy to synthesize the metastable perovskite SrIrO(3) and utilize in situ angle-resolved photoemission to reveal its electronic structure as an exotic narrow-band semimetal. We discover remarkably narrow bands which originate from a confluence of strong spin-orbit interactions, dimensionality, and both in- and out-of-plane IrO(6) octahedral rotations. The partial occupation of numerous bands with strongly mixed orbital characters signals the breakdown of the single-band Mott picture that characterizes its insulating two-dimensional counterpart, Sr(2)IrO(4), illustrating the power of structure-property relations for manipulating the subtle balance between spin-orbit interactions and electron-electron interactions.

Success of interventions in mastitis problems with Staphylococcus aureus after the introduction of an automatic milking system.

Staphylococcus aureus (S. aureus) is often the cause of mastitis problems in dairy herds and causes great economic losses. In this study, isolates from a dairy herd with a known S. aureus mastitis problem were examined by means of molecular methods (spa typing, PFGE, and DNA microarray) to investigate their epidemiological relationship and the success of intervention measures. The investigated dairy farm has a herd size of 60 cows and uses a fully automated milking system for milk production. A S. aureus strain, which contaminated the automated milking system and was subsequently spread among the herd through the latter, was suspected to be the origin of the mastitis problem within the herd. Thanks to the applied molecular methods, the common origin of the S. aureus isolates from the collected milk and swab samples could be shown. By culling chronically infected cows, optimising dry cow management and ensuring reliable intermediate cluster disinfection, the bulk milk somatic cell count improved.

Antimicrobial susceptibility of mastitis pathogens of dairy cows in Switzerland.

This study evaluates the antimicrobial resistance of pathogens cultured from 3'954 quarter milk samples from dairy cows in Switzerland. A total of 1'228 Streptococcus (Strep.) uberis, 1'107 Staphylococcus (Staph.) spp. other than Staph. aureus, 598 coliform, 490 Staph. aureus, 270 Enterococcus spp. and 213 Strep. dysgalactiae isolates were tested for susceptibility to 9 antimicrobial drugs using agar diffusion. Streptococcus uberis, Strep. dysgalactiae and Staph. aureus had the highest antimicrobial sensitivities to amoxicillin clavulanic acid (99.6 %, 100 % and 98.8 %, respectively). Of all isolated pathogens, only 2.6 % were resistant to amoxicillin clavulanic acid and 8.0 % to cefoperazone. The overall resistance level to gentamicin was 45.5 %, to penicillin 39.2 %, and to ampicillin 26.7 %. The highest resistance levels occurred with polymyxin (86.0 %), oxacillin (64.7 %) and lincomycin (53.7 %). Our results showed that at least one resistance exists to one antimicrobial agent examined in this study. Ideally the selection of the antibacterial drug for the treatment of intramammary infection should be based on antibiotic susceptibility testing.

On analyse dans la présente étude les résultats des tests de résistance aux antibiotiques de 3'954 échantillons de laits prélevés en Suisse. Au total, ce sont 1'228 souches de Streptococcus (Str.) uberis, 1'107 souches de Staphylococcus sp., 598 coliformes, 490 souches de Staphylococcus (S.) aureus, 270 souches d' Enterococcus et 213 de Str. dysgalactiae qui ont été testées par difffusion sur gel d'agar quant à leur sensibilité vis-à-vis de 9 substances antibiotiques. Ce sont les isolats de Str. uberis, Str. dysgalactiae et S. aureus qui ont montré la plus grande sensibilité face à l'association amoxicilline/acide clavulanique (99.6 %, 100 % resp. 98.8 % de souches sensibles). Par rapport à l'ensemble des germes isolés, ce sont l'association amoxicilline/acide clavulanique (2.6 %) et le céfoperazon (8 %) auxquels les germes ont été le moins souvent réséstants. Ils étaient suivis par la gentamycine (45.5 % de résistances), la pénicilline (39.2 %) et l'ampicilline (26.7 %). Les plus hauts taux de résistances ont été observés face à la polymyxine, (86 %), l'oxacilline (64.7 %) et la lincomycine (53.7 %). Sur la base des résultats de cette étude, on peut partir de l'idée qu'il existe des résistances contre toutes les substances testées. Le choix de l'antibiotique pour le traitement d'infections intra mammaires doit donc se faire idéalement sur la base d'un test de résistance préalable.

Interim PET response criteria in paediatric non-Hodgkin's lymphoma. Results from a retrospective multicenter reading.

AIM: To evaluate the use and reliability of the PET-based response criteria for interim PET (iPET) in terms of interobserver variability in pediatric and adolescent patients suffering from non-Hodgkin´s lymphoma (NHL). Particular attention was given to the identification of visual cutoff to separate patients with a favourable outcome. PATIENTS, METHODS: Retrospective analysis of PET-datasets of 18 children and adolescents suffering from NHL who underwent iPET after two cycles of chemotherapy for response assessment. Datasets were evaluated and rated in three independent review centers (RC) (blinded-read, intra-center consensus) using a visual 5-point response scale. Ratings were compared to clinical outcome. Pairwise interobserver agreement was analysed with Cohen's kappa-test (κ). Overall agreement (between attended RCs) was assessed with Fleiss' κ-test. RESULTS: Four patients suffered relapse (early, n = 2; late, n = 2). Per region analyses on interobserver variability revealed a "substantial" agreement (Fleiss' κ = 0.618). Per patient analyses revealed concordant iPET-ratings in eight patients: iPET-negative (iPET-), n = 5; iPET-positive (iPET+), n = 2; iPET-inconclusive (iPET±), n = 1. Discordant ratings were found in the remaining patients. Patients with early relapse were concordantly identified using mediastinal blood pool structures (MBPS, score ≥ 3) as visual cutoff between iPET+ or iPET-, respectively. However, patients with late relapse were not concordantly identified taking the MBPS as visual cutoff. CONCLUSION: The iPET interpretation using a dedicated PET-based response scale assured a low interobserver variability in per-region but not in per-patient analyses in a multicenter read. Using a sensitive read out (iPET+, score ≥ 3) a reliable identification of patients suffering relapse was limited to those with early relapse.

A2A adenosine receptor function in patients with vasovagal syncope.

AIMS: Adenosine is a possible mediator in vasovagal syncope (VVS) via the activation of its receptors. High expression of adenosine A2A receptors (A2AR) has been reported in VVS. The function of these over-expressed receptors in this population has never been evaluated. METHODS AND RESULTS: We used Adonis, a specific-made antibody with A2AR agonist properties, to evaluate binding parameters (i.e. dissociation constant KD) and cAMP production (i.e. EC50) by peripheral blood mononuclear cells of 16 VVS patients. Eight healthy volunteers served as controls. A2AR expression was higher in patients than controls; mean: 11.5 ± 1.2 vs. 7.7 ± 0.8 AU, P = 0.04. Also, KD values were higher in patients than controls: 2.1 ± 0.02 × 10(-7) vs. 5 ± 1 × 10(-8) M, P < 0.01 In controls, KD values were lower than EC50 (5 ± 1.7 × 10(-8) vs. 2.8 ± 0.4 10(-7) M, P < 0.01), but in patients, KD values did not differ from EC50: 2. ± 0.2 × 10(-7) vs. 2.5 ± 0.4 × 10(-7) M, P > 0.05. However, four patients had lower EC50 (3.5 ± 0.3 × 10(-8) M) than KD (2.9 ± 1.2 × 10(-7) M; KD/EC50 = 9.6), suggesting the presence of spare receptors. CONCLUSION: The function of A2AR of patients with VVS was preserved since their stimulation by Adonis led to cAMP production with an EC50 comparable with those in controls. However, their affinity was lower than those of controls. Our results suggest that A2AR are implicated in the physiopathology of VVS.

Evaluation of functional MR-urography in complex obstructive uropathy of infants: comparison to the conventional diagnostic algorithm--a pilot study.

OBJECTIVES: To analyze the impact of functional magnetic resonance urography (fMRU) on the therapeutic management in infants with complex obstructive uropathy (OU) compared to the conventional diagnostic algorithm [CDA, ultrasound, radioisotope nephrography (RN)]. METHODS: Retrospective analysis on 10 consecutive infants [female, n=3; male, n=7; age, 10.7 (2-17) months] with OU. Patients were examined according to CDA. If CDA revealed inconclusive results, fMRU was performed additionally. Split kidney function was assessed by RN [single kidney function (SKF)] and fMRU [volumetric differential renal function (vDRF)]. Findings were presented to an interdisciplinary truth-panel in a 2-step decision process (with and without fMRU). Clinical decision was determined. RESULTS: CDA indicated surgical intervention in 8 patients and conservative treatment in 2. Information by fMRU changed treatment strategy in 3 patients and led to the modification of the initially chosen surgical approach in 8 cases. The comparison of SKF and vDRF was not possible in 1 patient, whereas concordance was observed in 7 patients. SKF and vDRF differed >5% in 2 patients. CONCLUSIONS: fMRU has potential to improve therapeutic management of OU in infants. If surgical treatment is advised, the morphological information by fMRU has to be emphasized. Regarding kidney function estimation preliminary results are encouraging.

MRI versus bone scintigraphy. Evaluation for diagnosis and grading of stress injuries.

AIM: This study was set up to determine the value of magnetic resonance imaging (MRI) and bone scintigraphy (BS) for the diagnosis of stress injuries in athletes, and furthermore to assess reliability and prediction of healing time. PATIENTS, METHODS: Imaging data was analyzed retrospectively from 28 athletes who had received MRI and BS examinations for suspected stress injuries. MRI- and BS-data were rated by three specialists each in a blinded read, using a 5-point score (i.e. 0-4: inconspicuous to high-grade stress fracture). An interdisciplinary expert truth-panel set the reference standard. Standard statistical parameters, Fleiss' kappa (κ), and group comparisons were calculated. RESULTS: The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) for detection of stress injuries were 71.4%, 85.7%, 78.6%, 83.3% and, 75.0%, for MRI and 92.9%, 73.8%, 83.3%, 78.0% and, 91.2% for BS, respectively. Interobserver reliability for the diagnosis of a stress injury was κ = 0.9 for BS and κ = 0.85 for MRI. Mean healing times of mild (grades 1 and 2) and severe (grades 3 and 4) stress injuries were 88 days (d) versus 142d for BS and 57d versus 116d for MRI. No significant difference in healing time could be shown. CONCLUSIONS: MRI and BS reliably detect stress injuries. MRI is to be recommended as the primary imaging modality due to its potential for assessment of differential diagnoses and the lack of radiation exposure, the value of BS lies in the exclusion of stress fractures after inconclusive MRI examinations.

Discovery and structural elucidation of the illegal azo dye Basic Red 46 in sumac spice.

An unknown red dye was discovered in a sumac spice sample during routine analysis for Sudan dyes. LC-DAD and LC-MS/MS did not reveal the identity of the red substance. Nevertheless, using LC-high-resolution MS and isotope ratio comparisons the structure was identified as Basic Red 46. The identity of the dye was further confirmed by comparison with a commercial hair-staining product and two textile dye formulations containing Basic Red 46. Analogous to the Sudan dyes, Basic Red 46 is an azo dye. However, some of the sample clean-up methodology utilised for the analysis of Sudan dyes in food prevents its successful detection. In contrast to the Sudan dyes, Basic Red 46 is a cation. Its cationic properties make it bind strongly to gel permeation columns and silica solid-phase extraction cartridges and prevent elution with standard eluents. This is the first report of Basic Red 46 in food. The structure elucidation of this compound as well as the disadvantages of analytical methods focusing on a narrow group of targeted analytes are discussed.

Cell biology of H2O2 generation in the thyroid: investigation of the control of dual oxidases (DUOX) activity in intact ex vivo thyroid tissue and cell lines.

H2O2 generation by dual oxidase (DUOX) at the apex of thyroid cells is the limiting factor in the oxidation of iodide and the synthesis of thyroid hormones. Its characteristics have been investigated using different in vitro models, from the most physiological thyroid slices to the particulate fraction isolated from transfected DUOX expressing CHO cells. Comparison of the models shows that some positive controls are thyroid specific (TSH) or require the substructure of the in vivo cells (MßCD). Other controls apply to all intact cell models such as the stimulation of the PIP(2) phospholipase C pathway by ATP acting on purinergic receptors, the activation of the Gq protein downstream (NaF), or surrogates of the intracellular signals generated by this cascade (phorbol esters for protein kinase C, Ca(++) ionophore for Ca(++)). Still, other controls, exerted by intracellular Ca(++) or its substitute Mn(++), the intracellular pH, or arachidonate bear directly on the enzyme. Iodide acts at the apical membrane of the cell through an oxidized form, presumably iodohexadecanal. Cooling of the cells to 22°C blocks the activation of the PIP(2) phospholipase C cascade. All these effects are reversible. Their kinetics and concentration-effect characteristics have been defined in the four models. A general scheme of the thyroid signaling pathways regulating this metabolism is proposed. The probes characterized could be applied to other H2O2 producing cells and to pathological material.

Evaluation of interim PET response criteria in paediatric Hodgkin's lymphoma--results for dedicated assessment criteria in a blinded dual-centre read.

BACKGROUND: The aim of this study was to evaluate the use and reliability of the new positron emission tomography (PET)-based response criteria for interim positron emission tomography (iPET) in patients with paediatric Hodgkin's lymphoma (pHL). Particular emphasis was put on interobserver variability and on identification of a visual cut-off defining patients with very low risk for relapse. PATIENTS AND METHODS: The iPET scans of 39 pHL patients were evaluated in two independent centres by two PET-experienced specialists in nuclear medicine (blinded read, centre consensus) each. The iPET scans were interpreted using a 5-point scale and were compared with the outcome. Cohen's kappa-test (κ) was used to analyse the interobserver agreement. RESULTS: Concordant ratings were assessed in 19 patients with iPET-negative findings, in 11 patients with iPET-positive findings and in 2 patients with inconclusive ratings. A 'substantial agreement' between attended centres was achieved (κ = 0.748). All patients suffering relapse were concordantly identified, taking mediastinal blood pool structures (MBPS) as visual cut-off between PET-positive and PET-negative findings, respectively. All pHL patients with uptake lower than or equal to MBPS remained in complete remission. CONCLUSION(S): The iPET interpretation assured low interobserver variability. High sensitivity for identification of pHL patients suffering relapse is achieved if [18F]-fluorodeoxyglucose uptake above the MBPS value is rated as a PET-positive finding.

Clinical role of anti-granulocyte MoAb versus radiolabeled white blood cells.

Scintigraphy with white blood cells (WBC), labeled with ¹¹¹In-oxine or (99m)Tc-hexamethylpropyleneamine oxime (HMPAO), and anti-granulocyte scintigraphy using (99m)Tc-labeled monoclonal antibodies (MoAb), or fragments thereof, are established procedures for the diagnostic workup of infectious or inflammatory disease processes. Clinically severe afflictions such as fever of unknown origin (FUO), infectious joint replacements, osteomyelitis, vascular graft infections or cardiovascular infections often present where noninvasive proof of granulocytic inflammatory activity is more useful than mere morphology-based radiological diagnostic approaches. The labeling differences between WBC and antigranulocyte antibodies produce different pharmacokinetics and patterns of tracer accumulation and distribution. Together with the physical imaging properties of the respective isotope used for imaging, the diagnostic value of a tracer depends on the clinical setting. Thus, despite the easier and safer handling of antibody-based in-vivo labeling, indications for in-vivo labeled WBC remain. As a consequence there is as yet no ideal inflammation tracer, also bearing in mind that neither WBCs nor antibody-diagnostics can reliably differentiate sterile inflammation from infection. Although positron emission tomography (PET) using e.g. FDG-PET is replacing conventional scintigraphies in some indications, both in vivo and in vitro labelled leukocytes will remain an important clinical pillar in the diagnosis of infection and inflammation.

Incidental detection of breast cancer by 68Ga-DOTATOC-PET/CT in women suffering from neuroendocrine tumours.

AIM: Somatostatin receptor (sstr) imaging using 68Ga-DOTATOC-PET/CT in neuroendocrine tumors (NET) is promising, suggesting a more sensitive detection of lesions with a low sstr-expression. This is also important for other sstr positive tumors, especially breast cancer whose incidence and age-range is similar to that of NET. PATIENTS, METHODS: The PET/CT data of 33 consecutive women with NET (age: 33-78 years, mean 59) who underwent whole-body staging with 68Ga-DOTATOC was retrospectively analyzed for breast lesions. The data was read separately, side-by-side and as fused images. Focal tracer uptake in the breast was semiquantitatively analyzed by comparing the lesional SUVmax to normal breast tissue using Wilcoxon's rank sum test. Breast cancer lesions were compared visually to concomitant NET-lesions. RESULTS: In six of 33 patients (18%) breast lesions were observed on the CT-scans and classified in four patients (12%) as suspicious. The same lesions also showed a pathological tracer uptake on the corresponding PET-scan, visually and semiquantitatively (p<0.01). Histological reevaluation of the suspicious lesions revealed two patients with NET metastases. Two patients had primary breast cancer with lower tracer uptake than concomitant abdominal NET-lesions. Breast cancer diagnosis resulted in a change of the therapeutic regimen. CONCLUSION: 68Ga-DOTATOC-PET/CT not only improves the staging of NET-patients, but also increases the chance to detect sstr-positive breast cancer. Although these lesions may show a lower tracer uptake than NET, they must not be overlooked or misinterpreted as metastases. Further imaging and clarification by histopathology is warranted, as the confirmation of a secondary malignoma has great impact on further therapeutic proceedings.

Nuclear medical methods for the diagnosis of pancreatic cancer: positron emission tomography.

The functional imaging approach of nuclear medicine offers important information for the characterization of a tumor's pathobiology. In oncology, positron emission tomography (PET) especially has had great impact on the staging of tumor patients and the assessment of therapy. Both the development of new, tumor-specific, tracers and the introduction of by software- and hardware-driven image fusion emphasize the potential of this modality for an all-embracing diagnostic modality.

Detection of disease recurrence and monitoring of therapy.

The detection of disease recurrence and treatment monitoring pose high demands on diagnostic modalities. Whereas serum marker levels in most cases allow an assessment of tumor load and a respective response to therapy, they do not confer information on the localization of disease. Although this diagnostic gap is filled by imaging modalities, most techniques based on morphology will come to a limit when fibrotic tissue alterations have to be differentiated from viable tumor tissue in case of suspected recurrence or when residual masses after chemotherapy have to be assessed. The metabolic information on tumor cells gained by fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging appears not only to be more sensitive and reliable in this respect, but also appears to allow assumptions on response to therapy, and ultimately on patient prognosis.

Impact of image fusion and attenuation correction by SPECT-CT on the scintigraphic detection of parathyroid adenomas.

AIM: In addition to planar parathyroid scintigraphy, SPECT and image fusion with CT/MR improve adenoma detection in primary hyperparathyroidism (pHPT). This study evaluated the use of a hybrid SPECT-CT device concerning image fusion and attenuation correction (AC). PATIENTS, METHODS: The data of 26 patients with pHPT, preoperatively examined by (99m)Tc-sestamibi dual-phase scintigraphy plus SPECT-CT (low-dose CT), was retrospectively evaluated by two observers in a consensus reading. The images of planar scintigraphy, non-attenuation corrected SPECT (SPECT(NAC)), attenuation corrected SPECT (SPECT(AC)) and SPECT(AC)-CT were interpreted and compared to the results of surgery. The effect of AC on focus intensity was semiquantified by determination of the tumor-to-background (TB) ratio for SPECT(AC) and SPECT(NAC). Finally, the TB(AC)/TB(NAC)-ratio was calculated for each focus and correlated to the distance of a focus from the body surface. RESULTS: 20/26 (77%) patients were positive in planar scintigraphy. One focus was detected by SPECT only. AC of SPECT-data increased image contrast but had no impact on the detection rate. Additional SPECT(AC)-CT image fusion facilitated the localization of three mediastinal foci. In the semiquantitative analysis an increase in TB after AC was observed, although there was no strong correlation between depth of the focus (16-60 mm) and the TB(AC)/TB(NAC)-ratio (r = 0.213, p = 0.353). CONCLUSION: The detection rate of planar scintigraphy is only slightly improved by SPECT imaging. Due to the low spatial resolution of the CT component, the benefit of image fusion is limited to mediastinal foci. However, as TB and image contrast is measurably improved after AC there is a potential to improve the sensitivity of parathyroid SPECT.