Ventilation/Perfusion SPECT lung scintigraphy and computed tomography pulmonary angiography in patients with clinical suspicion of pulmonary embolism.

UNLABELLED: The aim was to compare ventilation/perfusion SPECT lung scintigraphy (V/Q-SPECT) and computed tomography pulmonary angiography (CTPA) in patients with suspicion of pulmonary embolism (PE). MATERIAL AND METHODS: This prospectively designed study included 53 patients with intermediate or high clinical probability of PE. A V/Q-SPECT and CTPA was performed on all patients. The V/Q-SPECT was interpreted according to the European Association of Nuclear Medicine and Molecular Imaging (EANMMI) guidelines. CTPA was reported as positive, negative, or indeterminate. RESULTS: CTPA was positive in 22 cases, negative in 28, and indeterminate in 3. V/Q-SPECT was positive in 27 cases, negative in 24, and non-diagnostic in 2. In the 22 with positive CTPA, V/Q-SPECT was positive in 18, negative in 3, and non-diagnostic in 1. In the 28 with negative CTPA, V/Q-SPECT was positive in 8, negative in 19, and non-diagnostic in 1. In the 3 with indeterminate CTPA, V/Q-SPECT was positive in 1 and negative in 2. In the 2 non-diagnostic cases V/Q-SPECT, CTPA was positive in 1 and negative in one. In the 10 high clinical probabilities, CTPA and V/Q-SPECT were positive in 7, negative in 2, and in 1, CTPA was positive and V/Q-SPECT negative. In the 38 intermediate probability group, CTPA and V/Q-SPECT were positive in 11, negative in 17, with CTPA negative and V/Q-SPECT positive in 8, and in 2 CTPA was positive and V/Q-SPECT negative. The results show that V/Q-SPECT detected PE in 5 patients more than CTPA. CONCLUSION: Our results show a 77% concordance of both techniques. Overall V/Q-SPECT detected PE in 18% more patients than CTPA in the intermediate group. Both techniques have a complementary role when a diagnosis cannot be made with one of them.

New insight of functional molecular imaging into the atheroma biology: 18F-NaF and 18F-FDG in symptomatic and asymptomatic carotid plaques after recent CVA. Preliminary results.

AIM: The identification of the vulnerable atheroma plaque could allow a more effective treatment of cerebrovascular accident (CVA). Active calcification and inflammation of the carotid atheroma were assessed and compared in symptomatic and asymptomatic plaques by 18F-NaF and 18F-FDG PET/CT. METHODS: Nine patients investigated for recent CVA and no preventive treatment with statins were enrolled. In each patient, at least one atheroma plaque was detected by CT angiogram. In total, 18 plaques were available: 9 symptomatic and 9 asymptomatic. 18F-NaF uptake and 18F-FDG uptake by each plaque were assessed visually and semiquantitatively by calculating target/background ratios (TBRs) and TBR indexes (TBR symptomatic/TBR asymptomatic and 18F-NaF TBR/18F-FDG TBR within each of the 2 clinical groups of plaques). RESULTS: All plaques showed 18F-NaF and 18F-FDG uptake, and semiquantitation showed higher 18F-NaF uptake by 11 of the 18 plaques, 6 symptomatic and 5 asymptomatic. In the symptomatic group, the mean 18F-NaF TBR was 2·12 ± 0·44, and in the asymptomatic group, it was 1·85 ± 0·46. The 18F-NaF/18F-FDG showed that, overall, 18F-NaF uptake is higher than 18F-FDG. In the symptomatic plaques, the 18F-NaF was higher for the low calcium content and the lowest for the high. CONCLUSION: Active calcification and inflammation are simultaneous processes in the symptomatic and asymptomatic carotid atheroma. However, active calcification seems predominant over inflammation in both groups. In the symptomatic plaques, the highest 18F-NaF uptake does not correspond with the largest calcium content. These patterns open new insights on the role of 18F-NaF in the study of calcification and in the identification of the vulnerable carotid atheroma.

Patterns of 11C-PIB cerebral retention in mild cognitive impairment patients.

OBJECTIVE: To evaluate the patterns of cerebral cortical distribution of (11)C-PIB in patients with mild cognitive impairment (MCI). MATERIAL AND METHODS: The study included 69 patients (37 male, age range 42-79 years) with MCI, sub-classified as 53 with amnestic-MCI (A-MCI), and 16 with non-amnestic-MCI (NA-MCI). Patients underwent (11)C-PIB PET/CT scan 60min after intravenous injection of the radiotracer. A visual analysis of the images was performed by 2 experienced physicians. (11)C-PIB-positive studies were considered when gray matter uptake was equal to or greater than white matter. According to the regions involved, (11)C-PIB-positive studies were classified into A-pattern (predominant retention in frontal, anterior cingulate, lateral temporal, and basal ganglia) and B-pattern (generalized retention). RESULTS: Thirty-nine of the 69 (56%) patients with MCI showed (11)C-PIB retention. Of the 53 A-MCI patients, 36 (68%) showed (11)C-PIB retention. Eleven out of 36 (30%) positive scans in A-MCI patients showed A-pattern, and 25 out of 36 (70%) patients had a B-pattern. Positive (11)C-PIB was observed in 3 out of 16 (19%) patients with NA-MCI. Regional distribution in these 3 patients showed A-pattern in 1, and B-pattern in 2 patients. CONCLUSION: Cortical retention of (11)C-PIB was more frequent in A-MCI than in NA-MCI patients, and also B-pattern than A-pattern in the (11)C-PIB positive group. The recognition of (11)C-PIB distribution patterns allows MCI patients to be classified, and the A-pattern may offer a therapeutic window for potential future treatments.

Use of positron emission tomography (PET) for the diagnosis of large-vessel vasculitis.

The term vasculitis encompasses a heterogeneous group of diseases that share the presence of inflammatory infiltrates in the vascular wall. The diagnosis of large-vessel vasculitis is often a challenge because the presenting clinical features are nonspecific in many cases and they are often shared by different types of autoimmune and inflammatory diseases including other systemic vasculitides. Moreover, the pathogenesis of large-vessel vasculitis is not fully understood. Nevertheless, the advent of new imaging techniques has constituted a major breakthrough to establish an early diagnosis and a promising tool to monitor the follow-up of patients with largevessel vasculitis. This is the case of the molecular imaging with the combination of positron emission tomography with computed tomography (PET/CT) using different radiotracers, especially the (18)F-fluordeoxyglucose ((18)F-FDG). In this review we have focused on the contribution of (18)F-FDG PET in the diagnosis of large-vessel vasculitis.

(18)F-FDG PET/CT for the detection of large vessel vasculitis in patients with polymyalgia rheumatica.

PURPOSE: Polymyalgia rheumatica (PMR) may present together with large vessel vasculitis (LVV), and frequently requires a more intensive therapy. The aim of the study was to evaluate the impact of (18)F-FDG PET/CT in the diagnosis and management of LVV associated to PMR. MATERIAL AND METHODS: This prospective study included 40 consecutive patients (27 women/13 men, 68.10±10.27 years) with PMR and suspicion of associated LVV submitted for (18)F-FDG PET/CT. A PET/CT scan was obtained 180 min after (18)F-FDG intravenous injection. A visual analysis was performed on the images. Five vascular regions were evaluated: supra-aortic trunks (SAT), thoracic aorta (TA), abdominal aorta (AA), iliac arteries (IA), and femoral/tibioperoneal arteries (FTA). The intensity of uptake was graded from 0 to 3. A final diagnosis of LVV was established in 26/40 patients (65%). RESULTS: In the 26 patients with a diagnosis of LVV, the highest intensity of (18)F-FDG uptake was observed in the TA, SAT, and FTA. All of these patients showed uptake at the TA, with grade 2 and 3 in most cases. In 4 of the 14 patients without LVV, no uptake was observed in any vascular region, and in the other 10 patients only a grade 1 uptake was observed in 1 or to 2 territories. Out of the 20 treated LVV patients, (18)F-FDG PET/CT led to a therapeutic change in 17 (85%). CONCLUSION: (18)F-FDG PET/CT was useful in identifying patients with LVV associated to PMR. The detection of vascular inflammation had an important impact, and led to a change of treatment in a high percentage of patients with LVV.

(18)F-sodium fluoride PET/CT for the in vivo visualization of Mönckeberg's sclerosis in a diabetic patient.

Diabetes is a major frequent cause of atherosclerosis vascular disease. Arterial calcification in diabetic patients is responsible for peripheral vascular involvement. Molecular imaging using (18)F-sodium fluoride ((18)F-NaF) positron emission tomography (PET)/computed tomography (CT) has been recently proposed as a marker to study the in vivo mineralization process in the atheroma plaque. A 69-year-old man with a history of type 2 diabetes and no clinical evidence of peripheral arterial disease underwent an (18)F-NaF PET/CT scan. A linear, well-defined (18)F-NaF uptake was detected along the femoral arteries. In addition, the CT component of the PET/CT identified an unsuspected "tram-track" calcification in his femoral arteries, suggestive of medial calcification (Mönckeberg's sclerosis). In other vascular territories, focal (18)F-NaF uptake was also detected in carotid and aorta atheroma plaques. Molecular imaging with (18)F-NaF PET/CT might provide new functional information about the in vivo vascular calcification process in diabetic patients.

Non-infectious aortitis: a report of 32 cases from a single tertiary centre in a 4-year period and literature review.

OBJECTIVES: Non-infectious aortitis often presents with non-specific symptoms leading to inappropriate diagnostic delay. We intend to describe the clinical spectrum and outcome of patients with aortitis diagnosed at a single centre. METHODS: We reviewed the clinical charts of patients diagnosed with non-infectious aortitis between January 2010 and December 2013 at the Rheumatology Division from a 1.000-bed tertiary teaching hospital from Northern Spain. The diagnosis of aortitis was usually based on FDG-PET-CT scan, and also occasionally on CT or MRI angiography or helical CT-scan. RESULTS: During the period of assessment 32 patients (22 women and 10 men; mean age 68 years [range, 45-87]) were diagnosed with aortitis. The median interval from the onset of symptoms to the diagnosis was 21 months. FDG-PET CT scan was the most common tool used for the diagnosis of aortitis. The underlying conditions were the following: giant cell arteritis (n=13 cases); isolated polymyalgia rheumatica (PMR) (n=11); Sjögren's syndrome (n=2), Takayasu arteritis (n= 1); sarcoidosis (n=1), ulcerative colitis (n=1), psoriatic arthritis (n=1), and large-vessel vasculitis that also involved the aorta (n=2). The most common clinical manifestations at diagnosis were: PMR features, often with atypical clinical presentation (n=23 patients, 72%); diffuse lower limb pain (n=16 patients, 50%); constitutional symptoms (n=12 patients, 37%), inflammatory low back pain (n=9 patients, 28%) and fever (n=7 patients, 22%). Acute phase reactants were increased in most cases (median erythrocyte sedimentation rate 46 mm/1st hour, and a median serum C-reactive protein 1.5 mg/dL). CONCLUSIONS: Aortitis is not an uncommon condition. The diagnosis is often delayed. Atypical PMR features, unexplained low back or limb pain, constitutional symptoms along with increased acute phase reactants should be considered 'red flags' to suspect the presence of aortitis.

Assessment of aortitis by semiquantitative analysis of 180-min 18F-FDG PET/CT acquisition images.

PURPOSE: The aim of this study was to evaluate the contribution of semiquantitative analysis of 180-min (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT images for the assessment of aortitis in cases of suspected large vessel vasculitis (LVV) and to establish a threshold index for application in the clinical setting. METHODS: This prospective study included 43 patients (mean age 67.5 ± 12.9 years) with suspicion of LVV (25 with a final diagnosis of aortitis). (18)F-FDG PET/CT scan was acquired 180 min after injection of 7 MBq/kg of (18)F-FDG. A semiquantitative analysis was performed calculating the aortic wall maximum standardized uptake value (SUVmax) (T), the lumen SUVmax (B) and the target to background ratio (TBR). These results were also compared with those obtained in a control population. RESULTS: The mean aortic wall SUVmax was 2.00 ± 0.62 for patients with aortitis and 1.45 ± 0.31 for patients without aortitis (p < 0.0001). The TBR was 1.66 ± 0.26 for patients with aortitis and 1.24 ± 0.08 for patients without aortitis (p < 0.0001). The differences were also statistically significant when the patients with aortitis and controls were compared. Receiver-operating characteristic (ROC) analysis revealed that the area under the curve was greater for the TBR than for the aortic wall SUVmax (0.997 vs 0.871). The highest sensitivity and specificity was obtained for a TBR of 1.34 (sensitivity 100%, specificity 94.4%). CONCLUSION: Semiquantitative analysis of PET/CT images acquired 180 min after (18)F-FDG injection and the TBR index of 1.34 show very high accuracy and, therefore, are strongly recommended for the diagnosis of aortitis in the clinical setting.

Contribution of V/Q SPECT to planar scintigraphy in the diagnosis of pulmonary embolism.

AIM: To evaluate the feasibility of V/Q SPECT and analyze its contribution to planar V/Q lung scintigraphy in the diagnosis of pulmonary embolism (PE). MATERIAL AND METHODS: A total of 109 patients with suspected PE showing Wells score>2 and elevated D-dimer were studied. The V/Q could not be completed in 7 patients, so they were excluded. Ventilation and perfusion scans were done using Technegas and (99m)Tc-MAA. Planar study included 8 projections on a 256×256 matrix and 128 projections on a 128×128 matrix were acquired for the SPECT study, applying an iterative method. Planar images were interpreted according to modified PIOPED criteria, and SPECT by the guidelines of the EANMMI. The results with both techniques were compared. RESULTS: V/Q planar scintigraphy and SPECT could be performed in 102 patients. V/Q planar scintigraphy was considered "diagnostic" in 39 of the 102 patients, and "non-diagnostic" in 63. Of the 39 "diagnostic" studies, 31 were reported as high probability of PE and 8 as normal. Of the 63 "non-diagnostic", 26 corresponded to intermediate, 29 to low, and 8 to very low probability. The SPECT study was "diagnostic" in 97 and indeterminate in only 5. All patients with a high probability planar scintigraphy had a positive SPECT. In the 8 patients with a normal planar scintigraphy SPECT was negative in 5 and positive in 3. In the 63 patients with a "non-diagnostic" planar scintigraphy SPECT was "diagnostic" in 58 of them, positive in 17 and negative in 41. CONCLUSION: V/Q SPECT is a feasible technique as it was performed in 102 of the 109 patients who were enrolled in the study (94%). The addition of V/Q SPECT to planar V/Q decreases the number of "non-diagnostic" reports from 62% in planar scintigraphy to 4.9% in SPECT. Therefore, V/Q SPECT should be included in the diagnosis approach of PE due to its high diagnostic yield.

Comparison of 99mTc-sestamibi and 11C-methionine PET/CT in the localization of parathyroid adenomas in primary hyperparathyroidism.

AIM: To evaluate the usefulness of (11)C-methionine PET/CT (MET) in the localization of the parathyroid adenomas and to compare the results with those obtained with the conventional technique in double-phase (99m)Tc-sestamibi scintigraphy (MIBI). We evaluated the optimal timing to acquire MET images. MATERIAL AND METHODS: A prospective study that included 14 patients (mean age: 65.5 ± 9.7 years) with primary hyperparathyroidism (PH) who underwent surgery was performed. Mean serum iPTH was 215.8 ± 108 pg/mL and serum calcium 10.8 ± 0.9 mg/dL. MIBI (planar and SPECT) was obtained 10 min and 2-3h after injection of 740 MBq (20 mCi) of (99m)Tc-sestamibi. MET was obtained 10 min and 40 min after injection of 740 MBq (20 mCi) of (11)C-methionine. MIBI and MET images were visually evaluated and compared. A score for 10 min and 40 min MET images from 0 (no abnormal uptake) to 3 (intense uptake) was assigned. RESULTS: MIBI and MET were positive and concordant in 11/14 patients and in 10 of them the parathyroid adenoma was correctly localized. In 3/14 MIBI was positive and MET negative (MIBI correctly localized the parathyroid adenoma in 2 of them). According to the timing of MET imaging acquisition, the 10 min and 40 min acquisition showed the same score in 10 patients, it was higher at 10 min acquisition in 3 and in 1 the parathyroid adenoma was only detected at 40 min acquisition. CONCLUSION: MIBI remains the technique of choice for the localization of parathyroid adenomas in patients with PH. MET may play a complementary role in selected patients. Delayed acquisition should be included in the MET protocol when the early acquisition is negative.

Actualización del uso de radiotrazadores PET en patología inflamatoria / Update on the use of PET radiopharmaceuticals in inflammatory disease

En la actualidad el uso de la imagen molecular con tecnología PET/TC con diferentes radiotrazadores, en especial la 18F-FDG, se está extendiendo más allá del ámbito de la oncología, siendo las enfermedades inflamatorias e infecciosas unas de las que más interés están despertando. En este artículo se hace una revisión de su aplicación y aportación en diferentes patologías inflamatorias en el contexto de las técnicas de imagen estructurales y de medicina nuclear convencional. Se hace especial énfasis en las de mayor entidad como son la vasculitis de grandes vasos, la sarcoidosis, la artritis reumatoide, la enfermedad inflamatoria intestinal y el estudio de la placa de ateroma (AU)

The use of molecular imaging with PET/CT technology using different radiotracers, especially the 18F-FDG is currently spreading beyond the area of oncology, the most interest being placed on inflammatory and infectious diseases. This article presents a review of its contribution in different inflammatory conditions in the context of structural and conventional nuclear medicine imaging. Special emphasis is placed on the more significant diseases such as large-vessel vasculitis, sarcoidosis, rheumatoid arthritis and inflammatory bowel disease and the study of the atheroma plaque (AU)

La neuroimagen molecular en las demencias degenerativas / Molecular neuroimaging in degenerative dementias

En el contexto de las limitaciones de la imagen estructural, los estudios de perfusión y metabolismo cerebral con SPECT y PET han aportado información relevante en el estudio del deterioro cognitivo. La introducción de radiotrazadores de amiloide cerebral ha replanteado la estrategia diagnóstica en torno a la enfermedad de Alzheimer (EA), considerada actualmente un «continuum». En este nuevo paradigma, la carga amiloide creciente se asocia al estadio preclínico y de deterioro cognitivo leve (DCL) de la enfermedad y ha podido ser objetivada en exploraciones «in vivo» gracias a la introducción del 11C-PIB y los tomógrafos PET. Las características de la imagen 11C-PIB son una elevada retención específica cortical cerebral en los casos positivos, con distribución topográfica característica y no retención en los negativos. Junto a la PET con 18F-FDG constituye la base de la neuroimagen molecular como biomarcador y se está valorando su significado pronóstico en estudios longitudinales. La PET con 11C-PIB se ha consolidado como la técnica óptima para valorar la presencia de amiloide cerebral, pero la necesidad de un ciclotrón cercano para su síntesis limita su disponibilidad, por lo que se están introduciendo trazadores análogos marcados con 18F. Nuestra experiencia en los 2 últimos años aplicando el 11C-PIB, primero en fase investigadora y después en la clínica, ha constatado la utilidad de la técnica en el campo asistencial, tanto de forma aislada como en combinación con la FDG. Así pues, la imagen de amiloide ha demostrado ser una herramienta útil en el diagnóstico diferencial de la demencia y un método prometedor de diagnóstico precoz y evaluación de tratamientos futuros(AU)

In the context of the limitations of structural imaging, brain perfusion and metabolism using SPECT and PET have provided relevant information for the study of cognitive decline. The introduction of the radiotracers for cerebral amyloid imaging has changed the diagnostic strategy regarding Alzheimer's disease, which is currently considered to be a «continuum.» According to this new paradigm, the increasing amyloid load would be associated to the preclinical phase and mild cognitive impairment. It has been possible to observe «in vivo» images using 11C-PIB and PET scans. The characteristics of the 11C-PIB image include specific high brain cortical area retention in the positive cases with typical distribution pattern and no retention in the negative cases. This, in combination with 18F-FDG PET, is the basis of molecular neuroimaging as a biomarker. At present, its prognostic value is being evaluated in longitudinal studies. 11C-PIB-PET has become the reference radiotracer to evaluate the presence of cerebral amyloid. However, its availability is limited due to the need for a nearby cyclotron. Therefore, 18F labeled radiotracers are being introduced. Our experience in the last two years with 11C-PIB, first in the research phase and then as being clinically applied, has shown the utility of the technique in the clinical field, either alone or in combination with FDG. Thus, amyloid image is a useful tool for the differential diagnosis of dementia and it is a potentially useful method for early diagnosis and evaluation of future treatments(AU)

[Update on the use of PET radiopharmaceuticals in inflammatory disease]. / Actualización del uso de radiotrazadores PET en patología inflamatoria.

The use of molecular imaging with PET/CT technology using different radiotracers, especially the (18)F-FDG is currently spreading beyond the area of oncology, the most interest being placed on inflammatory and infectious diseases. This article presents a review of its contribution in different inflammatory conditions in the context of structural and conventional nuclear medicine imaging. Special emphasis is placed on the more significant diseases such as large-vessel vasculitis, sarcoidosis, rheumatoid arthritis and inflammatory bowel disease and the study of the atheroma plaque.

Evaluation of the contribution of the dynamic phase of lymphoscintigraphy to the detection of sentinel lymph node in breast cancer.

AIM: The aim of this study was to evaluate the contribution of an early dynamic phase (DP) of the lymphoscintigraphy (LS) to the detection of the sentinel lymph node (SLN) in breast cancer. METHODS: This prospective study included 164 breast lesions in 161 consecutive patients (160 women, mean age 57.5 years). Patients with tumor >5 cm, multicentric, palpable nodes, axillary involvement, previous surgery, lymphadenectomy, radio or chemotherapy were not included. All patients underwent preoperative LS before surgery. DP immediately after injection of [99mTc]Nanocolloid followed by early and delayed planar images (EPI and DPI) were acquired. RESULTS: SLN was detected in 162/164 lesions (98.8%). In 115 (71%) DP showed no lymph node uptake and the SLN was identified only by EPI and DPI. A focal uptake by at least one lymph node was observed in DP in the remaining 47 lesions (29%). Although in 30/74 lesions DP did not provide additional information to EPI and DPI, nevertheless in 17 cases (10.5%) DP was essential to identify correctly the SLN. CONCLUSION: We concluded that DP, by allowing a better interpretation of the lymphatic drainage pattern, provides unique information to distinguish the correct SLN from other lymph nodes and is recommended as the first part of LS.

Molecular neuroimaging in degenerative dementias.

In the context of the limitations of structural imaging, brain perfusion and metabolism using SPECT and PET have provided relevant information for the study of cognitive decline. The introduction of the radiotracers for cerebral amyloid imaging has changed the diagnostic strategy regarding Alzheimer's disease, which is currently considered to be a "continuum." According to this new paradigm, the increasing amyloid load would be associated to the preclinical phase and mild cognitive impairment. It has been possible to observe "in vivo" images using 11C-PIB and PET scans. The characteristics of the 11C-PIB image include specific high brain cortical area retention in the positive cases with typical distribution pattern and no retention in the negative cases. This, in combination with 18F-FDG PET, is the basis of molecular neuroimaging as a biomarker. At present, its prognostic value is being evaluated in longitudinal studies. 11C-PIB-PET has become the reference radiotracer to evaluate the presence of cerebral amyloid. However, its availability is limited due to the need for a nearby cyclotron. Therefore, 18F labeled radiotracers are being introduced. Our experience in the last two years with 11C-PIB, first in the research phase and then as being clinically applied, has shown the utility of the technique in the clinical field, either alone or in combination with FDG. Thus, amyloid image is a useful tool for the differential diagnosis of dementia and it is a potentially useful method for early diagnosis and evaluation of future treatments.

Comparison of early (60 min) and delayed (180 min) acquisition of 18F-FDG PET/CT in large vessel vasculitis

Objetivo. Comparar la contribución de la adquisición con 18F-FDG-PET/TC a 180 min con la de 60 min en sospecha de vasculitis de grandes vasos (VGV). Material y métodos. Este estudio prospectivo incluyó 23 pacientes. El estudio PET/TC fue adquirido a 60 y 180 min (precoz y tardío) tras la administración de 18F-FDG. Se realizó un análisis visual de las imágenes valorando los troncos supraaórticos (TSA), la aorta torácica (AT), la abdominal (AA), las arterias ilíacas (AI) y las femoro/tibioperoneas (AFT). En las 115 regiones vasculares se evaluó la intensidad (0-3) y el patrón de captación (difuso/lineal). Resultados. En 20/115 regiones vasculares (17,4%) no hubo captación en la adquisición precoz y tardía. De las 95 regiones (82,6%) con captación en la adquisición precoz la intensidad no cambió en la tardía en 46 y cambió en 49. De esas 49 regiones en las que la intensidad cambió, esta disminuyó en 36 y aumentó en 13 (AT: 8, TSA: 5). En ningún caso la intensidad aumentó en la AA, las AI y las AFT. El patrón de captación en la AT fue difuso en la adquisición precoz en 16 pacientes, en 7 de ellos cambió a lineal en la tardía y desapareció en 9. El patrón precoz fue lineal en 7 pacientes, 6 de ellos mostraron un aumento de intensidad en la tardía y en uno permaneció igual. Conclusión. La adquisición tardía de 180 min con FDG-PET/TC proporciona una más detallada visualización de la pared vascular, mostrando la desaparición de la actividad del pool vascular y contribuyendo a un más correcto diagnóstico de VGV(AU)

Purpose. To compare the contribution of the 18F-FDG-PET/CT acquisition at 180 min and at 60 min in suspicion of large vessel vasculitis (LVV). Material and methods. A prospective study including 23 patients was performed. PET/CT was acquired at 60 and 180 min (early and delayed scan) after 18F-FDG injection. A visual analysis was performed at the supra-aortic trunks (SAT), thoracic aorta (TA), abdominal aorta (AA), iliac arteries (IA) and femoral/tibioperoneal arteries (FTA). Intensity (0–3) and uptake pattern (diffuse/linear) were assessed in the 115 vascular regions. Results. There was no FDG uptake in the early and delayed acquisition in 20/115 vascular regions (17.4%). Of the 95 regions (82.6%) showing FDG uptake at the early, delayed or both acquisitions, intensity did not change in the delayed acquisition in 46 and changed in 49. Of the 49 regions in which the intensity changed, it decreased in 36 and increased in 13 (TA:8, SAT:5). AA, IA and FTA intensity did not increase in any of the cases. Uptake pattern at the TA in the early acquisition was diffuse in 16 patients. In 7, it changed to linear and in 9 the uptake disappeared. The early pattern was linear in 7 patients and 6 of them showed increased intensity in the delayed acquisition and in 1 remained the same. Conclusion. The 180 min delayed FDG-PET/CT acquisition provides a more detailed visualized of the vessel wall, showing the washout of the blood pool activity. Therefore, it may contribute to a more accurate diagnosis of LVVAU)(AU)

Comparison of early (60 min) and delayed (180 min) acquisition of 18F-FDG PET/CT in large vessel vasculitis.

PURPOSE: To compare the contribution of the (18)F-FDG-PET/CT acquisition at 180 min and at 60 min in suspicion of large vessel vasculitis (LVV). MATERIAL AND METHODS: A prospective study including 23 patients was performed. PET/CT was acquired at 60 and 180 min (early and delayed scan) after (18)F-FDG injection. A visual analysis was performed at the supra-aortic trunks (SAT), thoracic aorta (TA), abdominal aorta (AA), iliac arteries (IA) and femoral/tibioperoneal arteries (FTA). Intensity (0-3) and uptake pattern (diffuse/linear) were assessed in the 115 vascular regions. RESULTS: There was no FDG uptake in the early and delayed acquisition in 20/115 vascular regions (17.4%). Of the 95 regions (82.6%) showing FDG uptake at the early, delayed or both acquisitions, intensity did not change in the delayed acquisition in 46 and changed in 49. Of the 49 regions in which the intensity changed, it decreased in 36 and increased in 13 (TA:8, SAT:5). AA, IA and FTA intensity did not increase in any of the cases. Uptake pattern at the TA in the early acquisition was diffuse in 16 patients. In 7, it changed to linear and in 9 the uptake disappeared. The early pattern was linear in 7 patients and 6 of them showed increased intensity in the delayed acquisition and in 1 remained the same. CONCLUSION: The 180 min delayed FDG-PET/CT acquisition provides a more detailed visualized of the vessel wall, showing the washout of the blood pool activity. Therefore, it may contribute to a more accurate diagnosis of LVV.

Metabolic response demonstrated by 18F-FDG-PET/CT in metastatic medullary thyroid carcinoma under sorafenib therapy.

A 51-year-old woman with a medullary thyroid carcinoma (MTC) presented with a palpable nodule in the right breast. Serum calcitonin was 1,453 pg/ml and carcinoembryonic antigen was 201 ng/ml. Cervical ultrasound and bone scintigraphy were normal. Computed tomography (CT) showed nodules in the right breast and anterior thoracic wall and a hypodense lesion in the right hepatic lobe. Histology of the breast nodule confirmed metastasis from MTC. To evaluate the metabolic activity of these lesions, 18F-fluorodeoxiglucose positron emission tomography-CT (FDG-PET/CT) scan was requested. Axial fused images revealed high FDG uptake by the breast and thoracic wall nodules and the right hepatic lobe. FDG-PET/CT also showed uptake in sacrum and right iliac bone, undetected by CT and bone scintigraphy. After seven cycles of sorafenib PET/CT became negative. Calcitonin decreased to 82.5. A PET/CT performed 6 months later remained negative. This is the first published image of the complete metabolic response of MTC to sorafenib therapy using FDG-PET/CT.