Slavomir Petras

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

BackgroundChronic 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 methodsRadionuclide 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). ResultsA 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. ConclusionThe 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.

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.

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

ObjectiveThe aim of the study was to evaluate the effect of 2-(18F)-fluoro-2-deoxy-D-glucose (18F-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 (SUVmax) of 2.5 in classifying and distinguishing benign/malignant pulmonary pathologies in 4D studies. Materials and methodsThirty-two patients with pulmonary lesions measuring 2 cm or less were included during their scheduled 18F-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 SUVmax percentage difference (%Diff SUVmax) was calculated. The nodule size, localization, and relationships with histological/cytological findings were studied. ResultsFifteen nodules were 10 mm or smaller and 17 were larger than 10 mm [mean size=12 mm (7–20)]. The mean 3D-SUVmax was 2.5 (0.7–6.1) and the mean 4D-SUVmax 3.2 (0.9–7.2) (P<0.001). The mean %Diff SUVmax 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-SUVmax of 3.8 (1.2–7.2). The cutoff SUVmax of 2.5 did not classify and distinguish between benign/malignant pulmonary pathologies, neither in 3D nor in 4D studies. ConclusionRespiratory gating improves the detectability and metabolic evaluation of solitary pulmonary nodules, mostly those that are subcentimetric. However, as expected, the cutoff SUVmax of 2.5 does not distinguish between benign/malignant lesions in either 4D or 3D studies.

Amoebic Abscess Diagnosed on Fluorodeoxyglucose Positron Emission Tomography Scan in Patient With Recurrent Oropharyngeal Squamous Cell Carcinoma

Case Report A 66-year-old man presented with a left perimandibular tumefaction at Institut Curie Hospital in September 2009. His previous medical history showed chronic tobacco use for two decades. Oropharyngeal cell squamous carcinoma was treated by surgery alone, a left pelvi-glossectomy, in November 2002. No adjuvant therapy was administered because no lymph node metastasis or surgical margin invasion was present. Tumoral recurrence of the tongue was diagnosed in May 2003 and was treated by exclusive local irradiation. A panendoscopy with directed biopsies was performed in September 2009 to explore the patient’s perimandibular tumefaction, and a posterior oropharyngeal tumoral recurrence was identified. Preoperative imaging using whole-body [F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) scan was performed showing an incidental intense pathologic oropharyngeal hyperfixation focus characterized by an increased maximum standardized uptake value (SUVmax) of 5 without any suspect lymphatic or visceral uptake. A new oropharyngectomy without complications and without adjuvant therapy was performed in November 2009. Three months later, an FDG-PET/CT scan performed to monitor tumoral disease identified two cervical hypermetabolic foci (SUVmax, 5.2 and 5.4) and two digestive hypermetabolic foci (SUVmax, 6.0 and 5.5; Fig 1). The patient had no infectious and/or abdominal symptoms, and no biologic abnormalities were identified. The clinical ear, nose, and throat examination concluded with a postoperative inflammatory reaction confirmed by a CT scan. A colonoscopy with directed biopsies was performed to explore the digestive foci of increased FDG uptake. A large ulcerated tumor of the right colon was observed (Fig 1). The histologic analysis of biopsies found an acute colitis with colonic mucosal ulcerations and inflammatory infiltration in the chorion. The colonic glands were well differentiated, and no tumoral proliferation was documented. The microscope examination showed large cells with off-centered nucleus and heavy cytoplasm containing hematic cells, which are findings in favor of parasitic agents such as Amoeba or Entamoeba histolytica (Fig 2). The diagnosis of an amoebic Fig 2.

Clinical Impact of Nonuniform Ct-based Attenuation Correction in Brain Perfusion Spect/ct Using 99mtc-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.

18F-FDG PET/CT findings in uterine leiomyomas.

A 43-year-old woman with a previous history of malignant melanoma of the lower limb was referred for F-FDG PET/ CT for suspected relapse after a routine CT scan revealed a ureterohydronephrosis. PET/CT revealed a large pelvic mass (a), containingmultiple extremely intense hypermetabolic nodular formations (b, c; SUVmax 23.5), compressing the right ureter. These formations presented with a hypometabolic centre suggesting fibrotic or necrotic remodelling. No abnormalities suggesting cutaneous or lymph node relapse were found. Pelvic MRI showed a uterus enlarged by multiple myometrial masses corresponding to the hypermetabolic nodular formations. These lesions were mildly hyperintense on T2-weighted images (d), enhanced after injection of gadolinium chelate (e), and were hypointense on diffusion-weighted images (f) suggesting highly cellular leiomyoma. However, the distinction between benign leiomyoma and malignant leiomyosarcoma on the basis of MRI features may be challenging [1].

Thyroid protection before 123I-ioflupane (DaTSCAN) imaging

Dear Sir, The European Association of Nuclear Medicine (EANM) procedure guidelines for brain neurotransmission single photon emission computed tomography (SPECT) imaging using I-labelled dopamine transporter ligands (version 2) published recently [1] assist nuclear medicine practitioners in clinical practice. However, we would like to clarify one point concerning thyroid protection before injection of Ilabelled tracers. This paper [1] contains a recommendation to protect the thyroid before iodine injection by perchlorate and the authors propose a 200-mg sodium perchlorate intake (or equivalent) at least 5 min before the injection of the radiopharmaceutical. The mechanism of potassium perchlorate action is well known nowadays [2]. The perchlorate anion is a potent iodine penetration inhibitor into the thyrocytes and is in competition with iodine at the sodium-iodide symporter located in the follicle cells’ basement membrane. The peak plasma level occurs 3 h after oral drug administration. The concentration inhibition mechanism of iodine at the thyroid gland level is achieved within 30–60 min after oral administration of perchlorate and during at least 6 h. After an intravenous injection of potassium perchlorate, blockage occurs immediately after administration. In France and in some other European countries, perchlorate is marketed as “potassium perchlorate” and not as sodium perchlorate. Sodium perchlorate had been previously marketed in Germany, in the Czech Republic and in Austria in a drinkable form (Irenat®) in the concentrations of 300 mg/ml (Austria) and 326.2 mg/ml (Germany) [3]. To our knowledge, it is no longer available on the market today. The group of University Hospitals of Paris (Assistance Publique des Hôpitaux de Paris, APHP) is producing this medicament in the form of potassium perchlorate capsules (200 mg) [4]. Other forms of the same medicament are capsules containing 200 mg of potassium perchlorate marketed in Italy (Pertiroid®) and the USA (Perchloracap®). Potassium perchlorate in the injection form is not manufactured nowadays. The manufacturer’s recommendation for blocking the thyroid gland is a dose of 200–400 mg of potassium perchlorate given at least between 30 and 60 min before radiopharmaceutical administration. Therefore, we think that thyroid blockage at least 30– 60 min is necessary before all injected I-labelled tracers.

Brain SPECT thallium using cadmium zinc telluride: a first experience.

A 70-year-old man underwent a thallium-201 brain SPECT in the work-up and characterization of a frontotemporal mass. SPECT images were performed on cadmium zinc telluride system during only 5 minutes and after the injection of only 2 mCi. Images demonstrated high thallium uptake in frontotemporal areas considered as a potential malignant tumor. Surgical removal confirmed the diagnosis of malignant glioblastoma. The thallium SPECT fast acquisition imaging on cadmium zinc telluride systems is feasible with reduced injected dose. This method allows a significantly decrease of patient radiation exposure without compromising the image quality. This initial experience needs to be confirmed and optimized in larger clinical studies.

Primary Jejunal Adenocarcinoma Incidentally Diagnosed on Positron Emission Tomography/Computed Tomography in a Patient With Metastatic Colorectal Cancer: Suspicion of Lynch Syndrome and Effect on Therapeutic Management

Case Report A 60-year-old woman with a previous medical history of a single left-colon adenoma with low-grade dysplasia (endoscopically resected in 1995) underwent a colonoscopy for abdominal pain in March 2010. The colonoscopy revealed a nonocclusive left-colon tumor, and biopsies revealed a well-differentiated adenocarcinoma. No familial history of cancer was reported. Multimodal imaging including a computed tomography (CT) scan and whole-body [F]fluorodeoxyglucose (FDG) positron emission tomography (PET) scan on a hybrid FDG-PET/CT device was performed for tumor staging. Both methods revealed metastatic colorectal cancer (CRC), and two synchronous right liver-lobe metastases were detected. No peritoneal tumoral disease was detected. The patient was referred to our institution in April 2010 for additional therapeutic management. Physical examination and laboratory tests were normal on admission. The metastatic disease was considered to be primarily resectable. As recommended by recent oncologic and surgical guidelines, neoadjuvant chemotherapy with infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX) was started. A partial tumor response according to RECIST (Response Evaluation Criteria in Solid Tumors) criteria was observed after six cycles of FOLFOX on CT and FDG-PET/CT scans. A right hepatectomy was performed in July 2010 followed by six postoperative cycles of FOLFOX and, later, by a left colectomy in September 2010. No peritoneal involvement was observed during liver and colon surgery. An asymptomatic intrathoracic recurrence was diagnosed in April 2011 on a CT scan, which showed a centimetric, isolated, and resectable pulmonary nodule without any other suspect lesion. A moderate pathologic hypermetabolism of the known pulmonary metastatic nodule (maximum standard uptake value [SUVmax], 3.5) was detected on an FDG-PET/CT scan as well as a single, incidental, intense, pathologic, hypermetabolic focus situated near the proximal jejunum that was characterized by an increased SUVmax of 14.6 (Fig 1; arrows indicate [A, B]

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.