Hybrid-fusion SPECT/CT systems in parathyroid adenoma: Technological improvements and added clinical diagnostic value / Sistemas de imagen híbrida de fusión SPECT/TC en adenoma de paratiroides: avances tecnológicos y valor añadido en el diagnóstico clínico

Nuclear medicine traditionally employs planar and single photon emission computed tomography (SPECT) imaging techniques to depict the biodistribution of radiotracers for the diagnostic investigation of a range of disorders of endocrine gland function. The usefulness of combining functional information with anatomy derived from computed tomography (CT), magnetic resonance imaging (MRI), and high resolution ultrasound (US), has long been appreciated, either using visual side-by-side correlation, or software-based co-registration. The emergence of hybrid SPECT/CT camera technology now allows the simultaneous acquisition of combined multi-modality imaging, with seamless fusion of 3D volume datasets. Thus, it is not surprising that there is growing literature describing the many advantages that contemporary SPECT/CT technology brings to radionuclide investigation of endocrine disorders, showing potential advantages for the pre-operative locating of the parathyroid adenoma using a minimally invasive surgical approach, especially in the presence of ectopic glands and in multiglandular disease. In conclusion, hybrid SPECT/CT imaging has become an essential tool to ensure the most accurate diagnostic in the management of patients with hyperparathyroidism (AU)

La medicina nuclear emplea tradicionalmente imágenes estáticas 2D, aunque en los últimos años se ha incrementado la imagen 3D tomográfica SPECT. Estas técnicas de imagen permiten la observación de la biodistribución de los radiotrazadores, destinados a la investigación diagnóstica de trastornos endocrinos que cursan con afectación glandular. La utilidad de combinar la información funcional con la anatómica tomando como referencia la tomografía computarizada (TC), la resonancia magnética (RM) y los ultrasonidos de alta resolución (US) ha sido estudiada mediante una correlación visual primero y posteriormente con el soporte de un software de co-registro de imágenes, sin obtener resultados satisfactorios. Los equipos híbridos SPECT/TC permiten la adquisición simultánea de diferentes modalidades de imagen, consiguiendo una fusión adecuada de ellas y su posterior reconstrucción volumétrica. Así pues, no es de extrañar que cada vez observemos mayor evidencia en la literatura que describe las múltiples ventajas de la tecnología SPECT/TC en la localización preoperatoria del adenoma de paratiroides con cirugía mínimamente invasiva, especialmente en presencia de patología multiglandular o de glándulas ectópicas. En resumen, la imagen híbrida se ha convertido en una herramienta esencial que garantiza la mayor exactitud diagnóstica en el manejo de pacientes con hiperparatiroidismo (AU)

Hybrid-fusion SPECT/CT systems in parathyroid adenoma: Technological improvements and added clinical diagnostic value.

Nuclear medicine traditionally employs planar and single photon emission computed tomography (SPECT) imaging techniques to depict the biodistribution of radiotracers for the diagnostic investigation of a range of disorders of endocrine gland function. The usefulness of combining functional information with anatomy derived from computed tomography (CT), magnetic resonance imaging (MRI), and high resolution ultrasound (US), has long been appreciated, either using visual side-by-side correlation, or software-based co-registration. The emergence of hybrid SPECT/CT camera technology now allows the simultaneous acquisition of combined multi-modality imaging, with seamless fusion of 3D volume datasets. Thus, it is not surprising that there is growing literature describing the many advantages that contemporary SPECT/CT technology brings to radionuclide investigation of endocrine disorders, showing potential advantages for the pre-operative locating of the parathyroid adenoma using a minimally invasive surgical approach, especially in the presence of ectopic glands and in multiglandular disease. In conclusion, hybrid SPECT/CT imaging has become an essential tool to ensure the most accurate diagnostic in the management of patients with hyperparathyroidism.

Mild to moderate increase of serum calcitonin levels only in presence of large medullary thyroid cancer deposits / Niveles séricos moderadamente elevados de calcitonina en presencia de grandes lesiones de cáncer medular de tiroides

Many open questions remain to be elucidated about the diagnosis, treatment and prognosis of medullary thyroid cancer (MTC). The most intriguing concerns the outcome of MTC patients after surgery. Great importance is usually given to serum calcitonin (Ct) and carcinoembryonic (CEA) levels. It is commonly believed that the higher are the levels of these tumor markers and their kinetics (double time and velocity of markers levels) the worst is the prognosis. However, this is not the rule, as there are huge MTC metastatic deposits characterized by low serum Ct and CEA levels, and this condition is not closely related to the outcome of the disease during post-surgical follow-up. A series is reported here of patients who have these characteristics, as well as a description of their prognosis and clinical outcome (AU)

Numerosas preguntas están pendientes de responder sobre el diagnóstico, tratamiento y pronóstico del cáncer medular de tiroides (MTC). El problema más intrigante se refiere a la evolución de los pacientes después de la cirugía. Por lo general, una gran importancia se le da a la calcitonina sérica (Ct) y los niveles de antígeno carcinoembrionario (CEA). Está ampliamente aceptado que cuanto mayor sean los niveles de estos marcadores tumorales y su cinética (tiempo de duplicación de los niveles), peor será el pronóstico. Sin embargo esta no es una regla: pueden existir grandes depósitos metastásicos de MTC que se acompañan de niveles bajos de Ct y CEA, y esta condición no está estrechamente relacionada con la evolución de la enfermedad durante de seguimiento postoperatorio. Presentamos una serie de pacientes con estas características y describimos su pronóstico y evolución clínica (AU)

Mild to moderate increase of serum calcitonin levels only in presence of large medullary thyroid cancer deposits.

Many open questions remain to be elucidated about the diagnosis, treatment and prognosis of medullary thyroid cancer (MTC). The most intriguing concerns the outcome of MTC patients after surgery. Great importance is usually given to serum calcitonin (Ct) and carcinoembryonic (CEA) levels. It is commonly believed that the higher are the levels of these tumor markers and their kinetics (double time and velocity of markers levels) the worst is the prognosis. However, this is not the rule, as there are huge MTC metastatic deposits characterized by low serum Ct and CEA levels, and this condition is not closely related to the outcome of the disease during post-surgical follow-up. A series is reported here of patients who have these characteristics, as well as a description of their prognosis and clinical outcome.

Early prediction of response by ¹8F-FDG PET/CT during preoperative therapy in locally advanced rectal cancer: a systematic review.

AIM: To assess the predictive value of fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) in early assessing response during neo-adjuvant chemoradiotherapy (CRT) in patients with locally advanced rectal cancer. MATERIALS AND METHODS: A systematic review was performed by search of MEDLINE Library for the following terms: "rectal carcinoma OR rectal cancer", "predictive OR prediction OR response assessment OR response OR assessment", "early OR ad interim", "therapy", "FDG OR (18)F-FDG", "PET OR PET/CT". Articles performed by the use of stand-alone PET scanners were excluded. RESULTS: 10 studies met the inclusion criteria, including 302 patients. PET/CT demonstrated a good early predictive value in the global cohort (mean sensitivity = 79%; mean specificity = 78%). SUV and its percentage decrease (response index = RI) were calculated in all studies. A higher accuracy was demonstrated for RI (mean sensitivity = 82%; pooled specificity = 85%) with a mean cut-off of 42%. The mean time point to perform PET scan during CRT resulted to be at 1.85 weeks. Some PET parameters resulted to be both predictive and not statistical predictive of response, maybe due to the small population and few studies bias. CONCLUSION: PET showed high accuracy in early prediction response during preoperative CRT, increased with the use of RI as parameter. In the era of tailored treatment, the precocious assessment of non-responder patients allows modification of the subsequent strategy especially the timing and the type of surgical approach.

(99m)Tc-DTPA scintigraphy assesses the absence of glomerular filtration rate impairment of Aliskiren in high-risk hypertensive subjects. A 12-month follow-up study.

AIM: Glomerular filtration rate (GFR) is commonly calculated using the modification of diet in renal disease (MDRD) and Cockroft-Gault (CG) formulas and recently by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) algorithm and not directly measured, so that the real impact of antihypertensive therapy on GFR could not be well defined. In this study, the effect of Aliskiren on the GFR measured by radionuclide clearance of 99mTc-diethylene triamine penta-acetic acid (DTPA) was investigated. METHODS: In 106 hypertensive subjects (53% men) aged 61.9±12.7 years with uncontrolled blood pressure (BP) receiving at least 2 antihypertensive medications, Aliskiren was added once-daily at a dose of 150-300 mg for 12 months. Clinic BP measurements were taken at every follow-up visit (1st, 6th and 12th month), while 24-hours ambulatory BP and GFR (in mL/min/1.73 m2) were evaluated at baseline and at the end of the follow-up. Analysis of variance for repeated measures of BP, GFR and microalbuminuria was provided. RESULTS: With the use of Aliskiren a significant reduction of BP and microalbuminuria was found (P<0.0001). Only in male population, a significant reduction in GFR calculated with CKD-EPI (82.4±15 vs. 78.6±18.2, P<0.01) and CG (81.6±29.5 vs. 74.2±28.4, P<0.0001) formulas was observed. This impairment of GFR was not found either with MDRD formula (70.5±19.6 vs. 68.3±23.4) or by radionuclide clearance (62.4±18.6 vs. 61.4±20.5). CONCLUSION: This study seems to demonstrate that the efficacy on BP control of Aliskiren is not accompanied by an impairment of GFR. In order to evaluate the effect of Aliskiren on GFR scintigraphy technique or MDRD formula resulted to be the most accurate methods.

Role of FDG PET/CT in investigating the mechanisms underlying atherosclerotic plaque formation and evolution

Este artículo se centra en el papel de la FDG PET/TC en la identificación de la aterosclerosis y en la relevancia de las células inflamatorias como los macrófagos y los linfocitos T en la formación de la placa aterosclerótica. Se discute también sobre la vulnerabilidad de la placa inflamatoria y el riesgo asociado a determinar incidentes cardio y cerebro-vasculares independientemente de la presencia de vasos estenóticos, así como sobre la evolución hacia la placa calcificada. El importante papel de la FDG PET/TC en el diagnóstico precoz de la placa inflamatoria se discute tanto en estudios con animales como a nivel clínico. Se discute, finalmente, la posibilidad de curar la placa inflamatoria, el tipo de fármacos utilizados y la posibilidad de controlar el tratamiento anti-inflamatorio a través de FDG PET/TC(AU)

This review article is focused on the role of FDG-PET/CT in visualizing atherosclerosis and on the relevance of inflammatory cells such as macrophages and T-lymphocytes in the formation of the atherosclerotic plaque. The vulnerability of the inflammatory plaque and the risk derived from the provocation of cardio- and cerebrovascular incidents independently from the presence of stenotic vessels are discussed as well as the evolution toward calcified plaque. The important role of FDG-PET/CT in early diagnosis of inflammatory plaque is discussed in both animal studies and in clinical setting. The possibility of curing inflammatory plaques, type of drugs, and the possibility of monitoring the anti-inflammatory treatment by FDG-PET/CT are also discussed(AU)

Role of FDG PET/CT in investigating the mechanisms underlying atherosclerotic plaque formation and evolution.

This review article is focused on the role of FDG-PET/CT in visualizing atherosclerosis and on the relevance of inflammatory cells such as macrophages and T-lymphocytes in the formation of the atherosclerotic plaque. The vulnerability of the inflammatory plaque and the risk derived from the provocation of cardio- and cerebrovascular incidents independently from the presence of stenotic vessels are discussed as well as the evolution toward calcified plaque. The important role of FDG-PET/CT in early diagnosis of inflammatory plaque is discussed in both animal studies and in clinical setting. The possibility of curing inflammatory plaques, type of drugs, and the possibility of monitoring the anti-inflammatory treatment by FDG-PET/CT are also discussed.

Diagnóstico de sarcoidosis desconocida asociada a eritema nodoso, mediante 18F-FDG PET/TAC / Diagnosis of unknown sarcoidosis associated to erythema nodosum with 18F-FDG PET/CT

Una mujer de 76 años fue remitida a nuestro Centro de Medicina Nuclear para someterse a 18F-FDG PET/TAC con sospecha clínica de vasculitis. La PET de cuerpo entero resultó negativa para vasculitis pero mostró hipermetabolismo moderado en varios ganglios linfáticos del mediastino y una captación intensa en las glándulas parótidas. Dado que la paciente refirió en anamnesis lesiones eritematosas de la piel en ambas piernas, realizamos una adquisición de PET de las extremidades inferiores que mostró una captación difusa en la región perimaleolar en ambas piernas. Sobre la base de los hallazgos de la PET/TAC que sugirieron sarcoidosis la paciente fue sometida a un lavado broncoalveolar (BAL) y a una biopsia de un ganglio linfático mediastínico que confirmó la sospecha de sarcoidosis(AU)

A 76-year-old woman was referred to our centre to perform 18F-FDG PET/CT with the clinical suspicion of vasculitis. Whole body PET was negative for vasculitis but it depicted moderate hypermetabolism in several lymph nodes of the mediastinum and intense uptake of the tracer in the parotid glands. Since the patient referred skin lesion on both legs a particular acquisition of the lower extremities was performed which showed diffuse uptake on the perimalleolar region of both legs. On the basis of the PET/CT findings that were suggestive for sarcoidosis the patient performed bronchoalveolar lavage (BAL) and biopsy of a mediastinal lymph node which confirmed the suspicion of sarcoidosis(AU)

Diagnosis of unknown sarcoidosis associated to erythema nodosum with 18F-FDG PET/CT.

A 76-year-old woman was referred to our centre to perform (18)F-FDG PET/CT with the clinical suspicion of vasculitis. Whole body PET was negative for vasculitis but it depicted moderate hypermetabolism in several lymph nodes of the mediastinum and intense uptake of the tracer in the parotid glands. Since the patient referred skin lesion on both legs a particular acquisition of the lower extremities was performed which showed diffuse uptake on the perimalleolar region of both legs. On the basis of the PET/CT findings that were suggestive for sarcoidosis the patient performed bronchoalveolar lavage (BAL) and biopsy of a mediastinal lymph node which confirmed the suspicion of sarcoidosis.

In high risk hypertensive subjects with incidental and unilateral renal artery stenosis percutaneous revascularization with stent improves blood pressure control but not glomerular filtration rate.

AIM: In high-risk hypertensive subjects (HTs) with incidental unilateral renal artery stenosis (RAS), the effectiveness of percutaneous revascularization with stent (PR-STENT) on blood pressure (BP) and glomerular filtration rate (GFR) is not established. METHODS: Eighteen HTs aged 65.7 ± 9.2 years with angiographically diagnosed unilateral RAS (≥ 60%) were randomized to receive PR-STENT (N=9) or to NO-STENT (N=9). BP (mercury sphygmomanometer) and GFR (99mTc-DTPA clearances during renal scintigraphy) were evaluated yearly for three years. Echo-Doppler of renal arteries was performed to verify the anatomic patency and flow velocities of the reperfused artery. Analysis of variance compared BP and GFR values changes from baseline to the follow-up; differences for continuous variables were evaluated between groups with the Tukey's post hoc test after adjustment for age, change of BP between baseline and at the follow-up, GFR and body mass index (BMI). RESULTS: Baseline systolic BP and GFR values were not different between groups. The significantly greater GFR increase observed in PR-STENT than in NO-STENT at univariate analysis at the end of follow-up (62.5 ± 19.2 vs. 42.24 ± 17.6, P<0.02) disappeared after adjustment for confounding factors. However, systolic BP remained significantly lower in PR-STENT than in NO-STENT (140.1 ± 4.6 vs. 170.0 ± 8.3, P<0.0001) also after adjustment for age, GFR and BMI. CONCLUSION: PR-STENT reduces systolic BP without improving GFR. Due to the strong association between high BP and renal damage, this study raises the question on whether PR-STENT should be performed in all HTs with unilateral and incidental RAS.

Arterial hypertension and thyroid disorders: what is important to know in clinical practice?

This review describes the pathogenic mechanisms of blood pressure (BP) regulation and long-term control in thyroid disorders. Variations from the euthyroid status affect virtually all physiological systems but the effects on the cardiovascular system are particularly pronounced. Thyroid disorders induce several hemodynamic changes leading to elevated BP as a consequence of their interaction with endothelial function, vascular reactivity, renal hemodynamic and renin-angiotensin system. However, in thyroid disorders, the regulation of BP and the development and maintenance of variable forms of arterial hypertension (HT) are different. Hyperthyroidism results in an increased endothelium-dependent responsiveness secondary to the shear stress induced by the hyperdynamic circulation, and contributes to reduce vascular resistance. Conversely, hypothyroidism is accompanied by a marked decrease in sensitivity to sympathetic agonists with an increase of peripheral vascular resistance and arterial stiffness. Furthermore in animal models, hypothyroidism reduces the endothelium-dependent and nitric oxide-dependent vasodilatation. HT due to thyroid disorders is usually reversible with achievement of euthyroidism, but in some cases pharmacological treatment for BP control is required. In hyperthyroidism, ß-blockers are the first-choice treatment to control BP but when they are contraindicated or not tolerated, ACE-inhibitors or calcium-channel blockers (CCB) are recommended. Hypothyroidism is a typical low rennin HT form showing a better antihypertensive response to CCB and diuretics; indeed in hypothyroidism a low-sodium diet seems further to improve BP control. Randomized clinical trials to compare the efficacy on BP control of the antihypertensive treatment in thyroid disorders are needed.

Comparison between 99mTc-sestamibi scintimammography and X-ray mammography in the characterization of clusters of microcalcifications: a prospective long-term study.

BACKGROUND: The early diagnosis of non-palpable breast cancer is the object of recent developments in the imaging procedures employed for screening purposes. In some patients, the presence of microcalcifications (MC) is the only indication of tumor. Although X-ray mammography (MRx) has high sensitivity in detecting MC, its specificity is however too low for diagnostic purposes. The aim of this study was to compare (99m)Tc-sestamibi scintimammography (SMM) and MRx in the differential diagnosis between benign and malignant clusters of MC and to assess the possible incremental value of SMM on specificity. PATIENTS AND METHODS: A total of 283 consecutive women (mean age 53+/-8 years) with MC identified on X-ray mammograms underwent SMM. Scintigraphic images were acquired 10 minutes after the i.v. injection of (99m)Tc-sestamibi (740 MBq). Planar images of both breasts were simultaneously obtained in the lateral prone position and in the anterior and oblique projections using a dual head camera. Sixty-nine women underwent surgery, whereas the remaining 214 patients had completely negative follow-up for 5 years (a 5-year follow-up period is considered the "gold standard" for diagnosing benign lesions). RESULTS: Histology demonstrated 32/69 primary breast carcinomas (prevalence of disease: 11% of all the 283 patients) and 37/69 benign lesions. The receiver operating characteristic (ROC) statistical technique was employed to compare the diagnostic value of Mrx alone to that of combined MRx and SMM. The detected difference between the areas under the MRx ROC curve (area=0.72, standard error 0.052) and the MRX and SMM ROC curve (area=0.86, standard error 0.039) was statistically significant (p<0.01). Moreover, the combination of MRx and SMM provided a significant improvement of the negative predictive value (NPV=98%) for MC with low-suspicion of malignancy at MRx. CONCLUSION: SMM can be considered as a complementary tool in the pre-operative work-up of patients with breast lesions. Furthermore, the high negative predictive value of this technique, makes it especially valuable in the perspective of reducing the number of negative breast biopsies or unnecessary surgical interventions.

Clinical applications of 68Ga-DOTANOC in neuroendocrine tumours.

Neuroendocrine tumours (NET) are relatively rare neoplasms affecting principally the gastroenteropancreatic tract, but with potential ubiquitary location, as the neural crest cells, origin of this group of tumours, are dispersed in various organs and tissues. After the discovery of somatostatin receptors (SSTR) over-expression in this group of neoplasms, NET management has significantly improved. This is witnessed by the development of new tracers in positron emission tomography (PET) imaging of NETs belonging to the family of radio-labelled somatostatin analogues, that significantly improved the accuracy of diagnosis and, more recently, opened the way to the innovative targeted radionuclide therapies. First introduced in clinical application in 2005, 68Ga-DOTANOC (one of the most used radio-labelled somatostatin analog for PET imaging) has revealed promising results in preliminary studies for the main clinical indications: staging NET; suspected NET of unknown primary; follow-up, restaging and, finally, for pre- and post-treatment evaluation of receptor radionuclide therapies. Due to its technically simple production, favourable biodistribution, biokinetics, dosimetry and high affinity for SSTR and thanks to the possibility of hybrid scans PET/computed tomography (CT) with better spatial resolution and localisation of the lesions, 68Ga-DOTANOC can advance as the new gold standard for imaging in neuroendocrine tumours.

Review. 18F-FDG PET in the diagnosis and follow-up of thyroid malignancy.

The diagnosis of carcinoma of the thyroid is usually made in the process of investigating a thyroid nodule with clinical examination, Technetium-99m scan, ultrasonography and fine-needle aspiration (FNA) cytology. The follow-up is mainly based on 123-iodine and 131-iodine scans and serum thyroglogulin measurement. The aim of the present review was to establish the role of 18F-FDG PET in the differential diagnosis of doubtful thyroid nodules and in the follow-up of patients with increased serum thyroglobulin levels and negative iodine-scan. It remains to be defined if metabolic imaging with PET could be a useful routine procedure in the management of thyroid tumours since the majority of them are well-differentiated and therefore have less avidity to 18F-FDG. In the present work we collected the specific literature derived from MEDLINE over the last 10 years to clarify the potential clinical value of 18F-FDG PET in thyroid malignancies. An emerging role for 18F-FDG PET is in the assessment of incidental finding of a thyroid nodule which, when showing high FDG uptake should be regarded as a possible malignancy that needs further assessment. Another well-documented role for 18F-FDG PET is in the investigation of cases of established well-differentiated thyroid carcinomas presenting with high thyroglobulin and negative iodine imaging. An increase of the 18F-FDG uptake in these tumours indicates a shift towards lesser differentiation (with more aggression and poor prognosis) and may benefit from alternative management. 18F-FDG PET can be considered a routine functional imaging method in detecting iodine-negative recurrent disease in thyroid cancer patients with elevated serum thyroglobulin levels during follow-up. 18F-FDG PET seems to be useful also in differential diagnosis of suspected thyroid nodules, especially using the semi-quantitative SUV analysis.

The role of 18F-FDG PET/CT in detecting metastatic deposits of recurrent medullary thyroid carcinoma: a prospective study.

AIM: To assess the diagnostic role of 18F-FDG PET/CT performed with a hybrid tomograph in the detection of tumoral deposits of recurrent medullary thyroid carcinoma (MTC). METHODS: Nineteen MTC patients with elevated serum calcitonin levels (58-1350 pg/ml) after first treatment were enrolled (11 F, 8 M, mean age 53.4 years, 14 sporadic MTC, 5 MEN-related MTC). All patients had previously undergone total thyroidectomy and lymphoadenectomy. When referred to us, they were studied with ultrasound (US), 18F-FDG PET/CT, (111)In-pentetreotide scan, and contrast-enhanced whole-body CT (c.e. CT). In 4 patients with equivocal abdominal findings at 18F-FDG PET/CT and/or at c.e. CT, laparoscopy was also performed. RESULTS: 18F-FGD PET/CT depicted metastases in 15 patients, 111In-pentetreotide in 8, c.e. CT in 11, US in 6. In 2 patients, liver micrometastases were detected at laparoscopy only. At a lesion-by-lesion analysis, 18F-FDG PET/CT visualized a total of 26 metastatic deposits, c.e. CT 18, 111In-pentetreotide 12, US 8. Final diagnosis was obtained by cytological or surgical findings. Four patients with evidence of limited metastatic spread to neck/upper mediastinum were re-operated, and in 2 of them serum calcitonin levels normalized. CONCLUSIONS: In our study, 18F-FDG PET/CT was the most sensitive imaging modality in detecting metastases in recurrent MTC patients with increased serum calcitonin levels. Moreover, 18F-FDG PET/CT was useful in some patients to plan a more accurate re-operation. From a diagnostic point of view, a multimodality imaging approach is recommended in recurrent MTC, especially based on the combination of c.e. CT and 18F-FDG PET/CT.

[PET/CT and thyroid carcinoma]. / La PET/CT nel carcinoma della tiroide.

In the present review we discuss the indications and clinical results of positron emission tomography (PET) in patients affected by differentiated thyroid cancer. It is well known that in this type of tumor the most used scintigraphy is based on 131-Iodine or 123-Iodine administration. However, a fraction of these tumors looses its capability to trap radioactive Iodine (this usually happens after multiple 131-Iodine treatments). This Iodine-negative- tumors are more frequently observed in the elderly and are characterized by a higher aggressiveness. Due to the poor clinical results of external radiotherapy and chemotherapy surgery remains the treatment of choice. Surgery can be performed with curative purposes also if the metastatic spread is visualized in an early phase. Among the various scintigraphic and radiologic techniques used, PET and PET-CT are reaching an even more important role in the early diagnosis of small tumoral deposits of thyroid cancer. The other issue we discuss in the present review is the potential value of PET and PET-CT in the differential diagnosis of suspected thyroid nodules.

An unusual case of a solitary pulmonary nodule associated with an abscess correctly distinguished by Pet/Ct fusion imaging.

The case of a male patient affected by concomitant solitary pulmonary nodule and chest abscess located on the same side and each close to the other is reported. The importance in differential diagnosis of these two lesions obtained by the 18F-FDG PET/CT fusion imaging examination is discussed.

[(111)In]Pentetreotide SPECT scintigraphy in neuroendocrine tumors: variability of reconstructing parameters related to patient characteristics and each body part.

AIM: Multi-headvariable-geometry gammacamera, allow us to carry out multi-dimensional scintigraphic single photon emission computed tomography (SPECT) studies, with the possibility of creating coronal, axial, sagittal, three-dimensional images like the last generation of multi-slice RMI or multislice CT scan. The aim of this paper is to weigh up the reconstruction parameters to apply in [(0111)In]Pentetreotide scintigraphy for evaluating neuroendocrine tumors and try to standardize them. METHODS: We have studied a group of 93 patients suffering from neuroendocrine tumors. Examination was carried out after administration of [111In] Pentetreotide with whole body and static acquisitions after 4 and 24 h, followed by SPECT acquisitions of head, thorax and abdomen after 24 h. RESULTS: The results obtained show that the Filtered Back Projection using Butterworth filter can produce images of greater resolution than the iterative reconstruction method. Moreover, the reconstruction parameters are easily standardizable for head and thorax while for the abdomen the choice of these parameters is more difficult. CONCLUSIONS: Our data show that filtered back projection with Butterworth filter is the best procedure to carry out a SPECT examination with [111In] Pentetreotide.

Accurate planning of minimally invasive surgery of parathyroid adenomas by means of [(99m)Tc]MIBI SPECT.

AIM: The aim of the study was to evaluate the clinical role or [(99m)Tc]MIBI SPECT in selecting primary hyperparathyroid (PHPT) patients for minimally invasive radioguided surgery (MIRS). METHODS: One hundred and forty-one consecutive PHPT patients were studied by a single-session [(99m)Tc]Percethnetate/[(99m)Tc]MIBI subtraction scintigraphy, followed by [(99m)Tc]MIBI SPECT in order to localize hyperfunctioning parathyroid adenoma (PA) and plan the surgical approach. RESULTS: A solitary PA was depicted at preoperative scintigraphy in 135 of 141 patients (95.7%), two or more PA in 5 patients, and was negative in 6 patients (4.3%). In 27 patients, the PA was located deep in the paraesophageal/paratracheal space. One hundred and twenty-four patients (in 18 of them the PA was located deeply in the neck) underwent successful MIRS using the low 37 MBq (1 mCi) [(99m)Tc]MIBI dose protocol. Intraoperative quick parathyroid hormone (QPTH) assay demonstrated a fall >50% in respect to the baseline value in all patients, confirming successful parathyroidectomy. After a follow-up of 6 to 37 months (median 18 months), no case of persistent/recurrent PHPT was recorded. When comparing the parathyroid to background (P/B) ratio measured at planar and SPECT preoperative scintigraphy with that measured intraoperatively with the gamma probe, a significant linear correlation was found between the SPECT and intraoperative gamma probe measurements (r = 0.91; P <0.01) while no correlation was found with planar scintigraphic data. CONCLUSIONS: Our data suggest that the P/B ratio calculated by means of [(99m)Tc]MIBI SPECT is more accurate in predicting the intraoperative measurements with the intraoperative gamma probe. Thus, a preoperative [(99m)Tc]MIBI SPECT acquisition should be recommended for a better selection of PHPT patients to offer MIRS.