Respiratory-gated imaging in metabolic evaluation of small solitary pulmonary nodules: 18F-FDG PET/CT and correlation with histology.

OBJECTIVE: The aim of the study was to evaluate the effect of 2-((18)F)-fluoro-2-deoxy-D-glucose ((18)F-FDG)-PET/computed tomography (CT) respiratory-gated imaging [four-dimensional (4D)] in the metabolic evaluation of small solitary pulmonary nodules and analyze the cutoff maximum standardized uptake value (SUV(max)) of 2.5 in classifying and distinguishing benign/malignant pulmonary pathologies in 4D studies. MATERIALS AND METHODS: Thirty-two patients with pulmonary lesions measuring 2 cm or less were included during their scheduled (18)F-FDG PET/CT examinations. The whole-body PET/CT acquisition (3D) was followed by a chest-centered PET/CT (4D) study synchronized with the respiratory cycle. The SUV(max) percentage difference (%Diff SUV(max)) was calculated. The nodule size, localization, and relationships with histological/cytological findings were studied. RESULTS: Fifteen nodules were 10 mm or smaller and 17 were larger than 10 mm [mean size = 12 mm (7-20)]. The mean 3D-SUV(max) was 2.5 (0.7-6.1) and the mean 4D-SUV(max) 3.2 (0.9-7.2) (P < 0.001). The mean %Diff SUV(max) was 38% for all patients (7-90), 45% in subcentimetric (7-90%) and 31% (7-75%) in supracentimetric lesions (P = NS). Histology was obtained in 23/32 (72%) cases and the pathologic benign/malignant ratio was 4/19. Malignancies were diagnosed as lung adenocarcinoma, solitary metastases, large cell lung carcinoma, and sarcoma in 13 (41%), 3 (9%), 2 (6%), and 1 (3%) case, respectively. Malignant lesions showed mean 4D-SUV(max) of 3.8 (1.2-7.2). The cutoff SUV(max) of 2.5 did not classify and distinguish between benign/malignant pulmonary pathologies, neither in 3D nor in 4D studies. CONCLUSION: Respiratory gating improves the detectability and metabolic evaluation of solitary pulmonary nodules, mostly those that are subcentimetric. However, as expected, the cutoff SUV(max) of 2.5 does not distinguish between benign/malignant lesions in either 4D or 3D studies.

Clinical impact of nonuniform CT-based attenuation correction in brain perfusion SPECT/CT using (99m)Tc-ECD.

INTRODUCTION: Brain perfusion SPECT is commonly used to evaluate patients with cognitive impairments. Physical limits such as attenuation compromise image quality do not allow the most accurate depiction of radionuclide distribution, and thus, application of attenuation correction (AC) has been recommended. Some reports have demonstrated discordances between the uniform (UAC) and nonuniform CT-based correction (NUAC) procedures. The aim was to study the impact of these discordances on visual interpretation and their concordance with clinical symptoms. METHODS: Twelve patients presenting cognitive impairments were included. Brain perfusion SPECT images were reconstructed using 2 AC methods. Qualitative image assessment was performed as uptake analysis in 21 predefined cortical ROIs for each patient. Interpretation of perfusion patterns was based on a 2-score uptake scale (normal and reduced/pathologic). Variation of uptake scores in UAC- versus NUAC-processed images and their concordance with clinical symptoms were studied. RESULTS: Normal image patterns generated by UAC and NUAC methods were found in 226 (90%) of 252 and in 201 (80%) of 252 ROIs, respectively. No difference between UAC and NUAC methods was found in posterior brain areas. However, differences were recorded in 51 (20%) of 252 ROIs, and this discordance was located in the anterior areas (frontal and temporal lobes), and evaluation changed from normal to pathological patterns using NUAC method. Two years later, patients showing frontal hypoperfusion on NUAC brain SPECT images expressed clinical frontal lobe dysfunctions. CONCLUSIONS: Discordances between UAC- and NUAC-processed images impact visual analysis of brain perfusion SPECT images. The NUAC-processed images show a good concordance with clinical symptoms, suggesting that it is an accurate method to correct attenuation.

Diagnosing diabetic foot osteomyelitis in patients without signs of soft tissue infection by coupling hybrid 67Ga SPECT/CT with bedside percutaneous bone puncture.

OBJECTIVE: Successful treatment of osteomyelitis is more likely with accurate diagnosis and identification of the causative pathogens. This typically requires obtaining a specimen of bone, usually by image-guided biopsy. We sought to develop a simpler bedside method for definitively diagnosing osteomyelitis. RESEARCH DESIGN AND METHODS: Over 2 years, we enrolled consecutive patients presenting to our diabetic foot clinic with a foot ulcer and clinically suspected osteomyelitis but without soft tissue infection. Each underwent hybrid (67)Ga single-photon emission computed tomography and X-ray computed tomography (SPECT/CT) imaging; those with a positive scan underwent bedside percutaneous bone puncture. Patients with a positive bone culture received culture-guided antibiotic therapy. Patients with negative (67)Ga SPECT/CT imaging or with positive imaging but negative bone culture were not treated with antibiotics. All patients were followed up for ≥ 1 year. RESULTS: Among 55 patients who underwent (67)Ga SPECT/CT imaging, 13 had negative results and all of their foot ulcers resolved without antibiotic therapy. Among 42 with positive imaging, 2 were excluded (for recent antibiotic therapy) and 40 had bone punctures (3 punctured twice): 19 had negative results, 3 of which were likely false negatives, and 24 had positive results (all gram-positive cocci). At follow-up, 3 patients had died, 3 had undergone amputation, and 47 had no evidence of foot infection. The sensitivity and specificity of this combined method were 88.0 and 93.6%, respectively, and the positive and negative predictive values were 91.7 and 90.7%, respectively. CONCLUSIONS: Coupling of (67)Ga SPECT/CT imaging and bedside percutaneous bone puncture appears to be accurate and safe for diagnosing diabetic foot osteomyelitis in patients without signs of soft tissue infection, obviating the need for antibiotic treatment in 55% of suspected cases.

Correlation between serum 25-hydroxyvitamin D concentrations and regional cerebral blood flow in degenerative dementia.

BACKGROUND: Chronic low serum vitamin D concentrations are common among the elderly. Recent studies have suggested that its metabolite, 25-hydroxyvitamin D (25-OHD), might be important for preserving cognitive functions through specific brain protective effects. However, this hypothesis is still under discussion. The aim of this study was to assess the correlation between serum 25-OHD concentrations and regional cerebral blood flow in neurodegenerative diseases such as Alzheimer's disease (AD) and dementia of Lewy bodies (DLB). PATIENTS AND METHODS: Radionuclide brain single-photon emission computed tomography/computed tomography (SPECT/CT) images and 25-OHD dosage in noninstitutionalized patients were obtained within 14 days. SPECT/CT examination was carried out using technetium-99m-ethyl cysteinate dimer in 20 consecutive patients (12 AD and eight DLB). Reconstructed images were spatially normalized using Statistical Parametric Mapping version 5 software to a default SPECT template. Voxel-based multiple regression correlation analyses, with age and mini mental state examination scores as confounding factors, were carried out. Findings were considered significant for a threshold P-value less than 0.01 (corrected at cluster level). RESULTS: A positive correlation was found between 25-OHD concentrations and regional cerebral blood flow in the left precuneus cortex (Talairach coordinates: -14, -42, 63) in AD patients. No correlation was detected in DLB patients. CONCLUSION: The results of this study confirm the relationship between 25-OHD concentrations and AD and therefore underline the hypothesis of a potential neuroprotective effect against brain degeneration. These encouraging findings need to be confirmed by larger prospective correlation series.

First experience DaTSCAN imaging using cadmium-zinc-telluride gamma camera SPECT.

We report our first experience of brain DaTSCAN SPECT imaging using cadmium-zinc-telluride gamma camera (CZT-GC) in 2 cases: a 64-year-old patient suffering from essential tremor and a 73-year-old patient presenting with atypical bilateral extrapyramidal syndrome. In both cases, 2 different acquisitions were performed and compared, using a double-head Anger-GC, followed immediately by a second acquisition on CZT-GC. There were no significant visual differences between images generated by different GC. Our first result suggests that DaTSCAN SPECT is feasible on CZT-GC, allowing both injected dose and acquisition time reductions without compromising image quality. This experience needs to be evaluated in larger series.

Brain perfusion SPECT imaging and acetazolamide challenge in vascular cognitive impairment.

Cerebrovascular disease is recognized as a common cause of cognitive impairment and dementia, alone or coexisting with other neurodegenerative diseases, mostly Alzheimer's disease. Vascular cognitive impairment (VCI) is a part of the heterogenous disorders group related to cerebral vessel disease. Although age is one of the most important risk factors for VCI, other common cardiovascular risk factors are also involved. By investigating these risk factors, a high proportion of these cognitive disorders can be prevented and/or delayed. Until now, only treatment of midlife arterial hypertension has been recognized as a preventing factor of vascular dementia. Brain MRI is becoming the method of choice to investigate cerebral vascular pathologies. However, this form of morphological imaging remains inadequate and does not provide useful functional information during VCI exploration, despite which functional imaging such as brain perfusion single-photon computed tomography, performed in baseline conditions and/or after an acetazolamide challenge, is underutilized in VCI exploration. The common strategies for VCI screening have not been standardized until now, and therefore further long-term imaging studies are needed to establish early diagnostic protocols. The present review summarizes the potential benefits of brain perfusion single-photon computed tomography imaging and possible scintigraphic quantification of cerebral hemodynamic reserves in investigation of VCI.

CT nonuniform attenuation and TEW scatter corrections in brain Tc-99m ECD SPECT.

Perfusion brain single photon emission computed tomography (SPECT) is currently used to evaluate patients with cognitive impairments. Although widely available, it has been reported to be significantly less sensitive than F-18 FDG positron emission tomography. Optimization of SPECT parameters using nonuniform attenuation correction (NUAC) and scatter correction (SC) might improve the accuracy of the method. This study assessed the effect of x-ray CT-based NUAC and triple-energy window (TEW-SC) on brain SPECT compared with Chang-uniform (UAC). A total of 31 patients with memory complaints underwent Tc-99m ECD SPECT/CT. CT-NUAC+TEW-SC and Chang-UAC were applied and compared. The images were spatially normalized to a default SPECT template supplied with Statistical Parametric Mapping software (SPM2). A paired t test image was then reconstructed. Regional cerebral blood flow measurements were apparently reduced in the frontal white-matter and in the frontotemporal cortex when CT-NUAC+TEW-SC were used. These findings need to be considered when interpreting Tc-99m ECD SPECT after applying CT-AC+TEW-SC. Further prospective studies with clinical correlations are needed.

[Brain SPECT in Lewy body dementia]. / Scintigraphie cérébrale et démence à corps de Lewy.

Dementia of Lewy bodies (DLB) is the second cause of degenerative dementia. There is many clinical presentation of the disease. Brain single photon computed tomography (SPECT) is a simple way to investigate routinely the cerebral blood flow. On cerebral perfusion SPECT, DLB is accompanied by diffuse cortical hypoperfusion predominantly at the posterior cortex and may affect the associative and primary visual areas in relation to neuronal loss or dysfunction. DLB patients have striatal hypofixation on cerebral neurotranmission SPECT-DaTSCAN(®), related with dopaminergic loss. Brain SPECT is useful in the differential diagnosis between DLB and other dementia.

Is brain SPECT useful in degenerative dementia diagnosis?

Cerebral blood flow assessment performed by single-photon emission computed tomography (SPECT) of the brain is used to detect early neuronal dysfunction associated with degenerative dementia. Patterns of perfusion abnormalities are different across dementia syndromes. These differences could be used for differential diagnoses and early detection of amnesic mild cognitive impairment in patients with a high risk of conversion to Alzheimer disease. This paper aimed to summarize the expected benefits of single-photon emission computed tomography of the brain in the exploration of degenerative dementias.

[Perfusion brain SPECT and Alzheimer disease]. / Scintigraphie cérébrale de perfusion dans la maladie d'Alzheimer.

Alzheimer Disease (AD) is the most frequent cause of degenerative dementia. There is an asymptomatic phase of the disease. Brain single photon computed tomography (SPECT) is a simple way to investigate the cerebral blood flow. Alzheimer's disease is characterized by hypoperfusion in the medial temporal, associative posterior parietal cortex and frontal cortex. Brain SPECT could also have an interest in the early detection of amnesic mild cognitive impairment (MCI) patients with a high risk of conversion to AD. Indeed, the hypoperfusion of the associative parietal cortex in MCI patients is considered predictive of a rapid conversion to AD. Different scintigraphic patterns of neurodegenerative dementias could be used for their differential diagnosis.

Bone pain due to fractures revealing osteomalacia related to tenofovir-induced proximal renal tubular dysfunction in a human immunodeficiency virus-infected patient.

Tenofovir is a nucleoside reverse transcription inhibitor used to treat human immunodeficiency virus patients with early treatment failure. Increasing numbers of cases of tubular dysfunction and Fanconi syndrome have been reported in patients treated with tenofovir, after the detection of biochemical abnormalities during routine assessments. Some patients have acute renal failure, and bone involvement is observed in rare cases. We describe a case of chronic metabolic complications with bone fractures related to tenofovir treatment. Several factors that increased the renal toxicity of tenofovir included low body mass index, concomitant use of nonsteroidal anti-inflammatory agents, and other antiretroviral drugs, including ritonavir.

Treatment of adult systemic mastocytosis with interferon-alpha: results of a multicentre phase II trial on 20 patients.

Systemic mastocytosis (SM) is characterized by proliferation of mast cells in various organs, which may release a wide variety of mediators, thereby explaining the broad clinical spectrum of disease manifestations. The potentially life-threatening systemic symptoms and tumoral proliferation are poorly controlled despite the use of several cytotoxic chemotherapies and/or symptomatic treatments. Twenty consecutive adult SM patients with histologically confirmed bone marrow (BM) involvement received interferon-alpha subcutaneously (1-5 million units/m2/d, with progressive dose intensification over the first month of treatment) and were evaluated after 6 months of therapy. Seven of them had previously received symptomatic treatments, including steroids, which were ineffective. Among the 13 patients treated for at least 6 months, seven partial and six minor responses, mainly concerning vascular congestion and skin lesions, were obtained, while BM infiltration remained unchanged in 12 patients. The significant reduction of mast-cell mediator levels after 6 months of treatment was not predictive of clinical remission. The rate of depression was unexpectedly high (seven patients; 35%). Two patients died soon after starting therapy (one myocardial infarction, one septic shock). Six months of interferon-alpha may relieve vascular congestion in adults with SM, probably by inhibiting mast-cell degranulation.