Accuracy of 18F-FDG PET/CT in patients with the suspicion of cardiac implantable electronic device infections

BACKGROUND

Utility of 18F-FDG PET/CT in diagnosing infective endocarditis (IE) associated with cardiac implantable electronic devices (CIEDs) is not well established. Current ESC guidelines recommend the use of FDG-PET imaging in patients with CIEDs and positive blood cultures, but the number of studies evaluating the diagnostic performance of FDG-PET imaging in these patients remain limited. Our objective was to assess the diagnostic yield of 18F-FDG PET/CT in patients with suspected CIED infections, differentiating between pocket infection (PI) and lead infection (CIED-IE).

METHODS AND RESULTS

From 2013 to 2018, all patients (n = 63) admitted to a hospital with suspected CIED infection were prospectively recruited, undergoing a diagnostic work-up including a PET/CT. Explanted devices and material from the pocket were cultured. 14 cases corresponded to isolated PI and 13 were categorized as CIED-IE. Considering radionuclide uptake in the intracardiac portion of the lead, sensitivity and specificity of PET/CT for CIED-IE were 38.5% and 98.0%, respectively. Positive (19.2) and negative (0.6) likelihood ratio values, suggest that a positive PET/CT is much more probable to correspond to a patient with CIED-IE, whereas it is not possible to exclude this diagnosis when negative. For PI, sensitivity and specificity were 72.2% and 95.6%, respectively.

CONCLUSIONS

The yield of 18F-FDG PET/CT for suspected CIED infections differs depending on the site of infection. Due to very high specificity but poor sensitivity, negative studies must be interpreted with caution if the suspicion of CIED-IE is high.

Contralateral axillary sentinel lymph node drainage in breast cancer: Controversies and management according to the literature. A case report

Lymphoscintigraphy in breast cancer usually shows lymphatic drainage to the ipsilateral axilla. Drainage to extraaxillary or contralateral axillary regions is rare and there is still controversy about its management. Due to the significant clinical impact of an accurate staging, a literature research is made based on a case of a patient with recurrence of left breast cancer with contralateral axillary sentinel lymph node detection, without evidence of lymphatic drainage to other locations.

Breslow thickness and (18)F-FDG PET-CT result in initial staging of cutaneous melanoma: Can a cut-off point be established?

AIM

To establish a Breslow Thickness (BT) cut-off point for indication of PET-CT of cutaneous melanoma in early stages and evaluate its prognostic value.

MATERIAL AND METHODS

Retrospective analysis of 347 PET-CT studies with diagnosis of melanoma, of which 108 were performed for initial staging. Thirty-one patients were excluded, and a final sample of 77 patients remained. A ROC curve analysis was performed to establish an optimal cut-off point. A survival analysis was performed, considering death assignable to melanoma as the main event, for the evaluation of its prognostic value.

RESULTS

Forty-seven (61.04%) of all 77 patients selected were men, and 11 (14.29%) had a positive PET-CT result. Mean age was 65.17±15.00 years. The median BT in patients with a negative PET-CT result was 2.75 mm (IQR 1.83-4.50) and in the positive group 6.25 mm (IQR 5.40-7.50) (P=.0013). In the ROC curve analysis (AUC 0.804, SE 0.054), an optimal value of 5 mm BT with the following values was obtained: sensitivity 90.91%, specificity 78.79%, negative predictive value (NPV) 98.1%, positive predictive value (PPV) 41.7%, diagnostic OR 37.1, and accuracy 80.52%. Mean follow-up was 18.66±14,35 months, detecting 2/53 (3.77%) deaths in the BT<5 mm group, and 7/24 (29.17%) in the BT≥5 mm group. Survival curves between both groups were significantly different (P=.0013).

CONCLUSIONS

A 5 mm cut-off point correctly distinguishes those patients with positive PET-CT from those with negative results in the early stages of cutaneous melanoma; therefore it could be included in initial staging of this subgroup of patients.

[Meta-analysis of the diagnostic performance of 18F-FDG PET in renal cell carcinoma]

AIM

Renal cell carcinoma is the most frequent solid kidney tumor. At present, PET is not the imaging test of choice, the helical CT being the best method to assess these patients. The aim of the study was to perform a meta-analysis of the literature to evaluate the performance and accuracy of 18F-FDG PET in the detection of primary disease, recurrence and metastasis of renal cell carcinoma.

MATERIALS AND METHODS

A systematic search was done of the available literature in primary and secondary databases published until October 2004 indexed in MEDLINE and CANCERLIT. Exclusion/inclusion criteria were applied. Their quality was evaluated using the Flynn criteria and joint estimators of sensitivity (S), specificity (Sp), likelihood ratios (LR), diagnostic odds ratio (DOR) and summary ROC (SROC) curve were obtained. The presence of the threshold effect was evaluated and the summary ROC (SROC) curve was calculated.

RESULTS

Seven out of 46 studies fulfilled the inclusion criteria and were analyzed. Three studies evaluated the use of 18F-FDG PET in the differential diagnosis of renal masses. Two studies analyzed restaging and two analyzed the role of 18F-FDG PET in the detection of metastatic disease. All the selected studies were classified according to Flynn's criteria. We found the highest S in restaging with S 0.87 (95 % CI, 0.75-0.95) and in metastases detection with S 0.72 (95 % CI, 0.56-0.85) as well as the high Sp in differential diagnosis of renal masses.

CONCLUSIONS

The results of this meta-analysis suggest that 18F-FDG PET can be useful in restaging and detection of metastatic disease, based on its acceptable S and Sp. However, the performance of 18F-FDG PET in the detection of primary disease is limited, but this may improve with the new PET/CT systems.

Recurrencia de un carcinoma gástrico de células en anillo de sello demostrada por PET-FDG

OBJECTIVE

To present the case report of a patient with undifferentiated and diffuse signet-ring cell gastric carcinoma in which FDG-PET evidenced recurrent disease.

MATERIALS AND METHODS

The patient was diagnosed of a stage III gastric carcinoma in 1994 and was treated with a subtotal gastrectomy. In February 2003, recurrent disease was detected in mediastinal and left supraclavicular lymph nodes. The patient was treated with chemotherapy and radiotherapy, reaching a complete response. After 6 months free of disease, he presented an elevation of the tumor markers with negative results in conventional imaging methods (upper digestive endoscopy, bone scintigraphy, and CT). An FDG-PET scan was performed to rule out recurrent disease.

RESULTS

FDG-PET detected pathologic findings suggestive of malignant disease in right supraclavicular and mediastinal lymph nodes. These findings were confirmed by clinical follow-up and with another CT scan performed 4 months later.

CONCLUSIONS

In this case report we stress the importance of early recurrence by FDG-PET in a non-intestinal gastric carcinoma. This is of interest given the greater difficulty to detect mucous secreting and/or producing carcinomas with the PET-FDG.

Impacto de la tomografía por emisión de positrones mediante 18-Fluoro-2-Desoxi-D-Glucosa (PET-FDG) en el manejo terapéutico de pacientes con recurrencia secundaria a cáncer de ovario

AIM

Recurrent ovarian cancer is a major problem and an accurate diagnosis can often change patients' management. This study aimed to assess the impact on management of FDG-PET in recurrent ovarian cancer.

MATERIAL AND METHODS

Forty-three patients in whom FDG-PET scan was performed due to suspected recurrent ovarian cancer were included. FDG-PET results were confirmed by histopathology and clinical follow-up of at least 12 months. To assess impact on management the treatment plan based on conventional imaging methods was compared with the treatment plan based on inclusion of PET findings, classifying FDG-PET impact on management as high, medium, low or no impact. Management changes, when present, were classified as intermodality or intramodality.

RESULTS

FDG-PET had a high impact on therapeutic management in 28 patients (65.1 %), medium impact in 2 patients (4.6 %), low impact in 9 patients (20.9 %), and no impact in 4 patients (9.3 %). FDG-PET induced an intermodality change in management in 27 patients (62,8 %); intramodality changes were induced in 3 patients (7 %). Finally, it produced no treatment changes in 13 patients (30.2 %).

CONCLUSION

FDG-PET supplied additional information when compared to conventional diagnostic procedures and allowed adequate management changes in most patients.

PET-FDG en paciente con enfermedad de Von Recklinghausen y neurofibrosarcoma dorsal izquierdo

The development of neurofibrosarcomas in patients with Von Recklinghausen disease is a rare complication that can appear in the daily clinical practice. We report a clinical case with Von Recklinghausen disease and recurrence of a left dorsal neurofibrosarcoma diagnosed by Positron Emission Tomography with fluorine-18-fluoro-deoxyD-glucose (FDG-PET). We believe this work is important due to the relatively uncommon clinical presentation and the discussion on the utility of 18-FDG PET and other conventional imaging methods in the diagnosis of this entity.

Early diagnosis of recurrent breast cancer with FDG-PET in patients with progressive elevation of serum tumor markers

BACKGROUND

The aim of this work is to assess the diagnostic value of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG), in the early detection of tumour recurrence in already treated breast cancer patients in apparent complete remission and with a progressive elevation of tumour markers CEA and/or CA 15.3 without any other clinical or instrumental signs of relapses.

METHODS

The author studied 45 women (mean age 58+/-12, range 35-80 years) with histological diagnosis of breast cancer who underwent a tumour marker-guided whole body FDG-PET. All patients were in remission, without any other clinical or instrumental signs of relapses, except for the progressive elevation of CA 15.3 and/or CEA, tested during the follow-up. FDG-PET results were controlled by pathology when histological sampling was possible, by other conventional imaging modalities (US, X-rays, CT, MRI) and/or by clinical follow-up up to 12 months at least.

RESULTS

FDG-PET findings were evaluated in 38 patients: 27 resulted positive. Among these 27 PET positive patients 24 were true positive and 3 false positive. Tumour marker guided FDG-PET was also able to discover 3 unknown neoplasms not visualized by other modalities. PET revealed 54 sites of intense focal FDG uptake. The anatomical distribution of these sites was 19 skeleton, 18 lymph node basins, 5 liver, 5 pelvic region, 1 lung, 1 pericardium, 1 pleura, 1 contralateral breast, 2 peritoneum and 1 thyroid bed. Forty-eight of these 54 sites of FDG accumulation were confirmed to be metastases. FDG-PET resulted negative in 11 patients and only in 2 of them the other diagnostic modalities were able to discover metastatic lesions; we had 9 true negative and 2 false positive RESULTS. On the basis of our investigation the performances of tumour marker guided FDG-PET per patient are as follows: sensitivity 92% (24/26), specificity 75% (9/12), positive predictive value 89% (24/27), negative predictive value 82% (9/11), accuracy 87% (33/38).

CONCLUSIONS

This study demonstrated the clinical utility of tumour marker-guided PET in the follow-up of breast cancer patients. This diagnostic approach allowed to modify the clinical management in those patients in whom a tumor relapse or unexpected primary neoplasm was discovered.

[Neuroimaging in epilepsy. Advances in SPECT and PET in epilepsy]

INTRODUCTION

The incorporation of neuroimaging techniques into the protocol for localization of epileptogenous foci has considerably reduced the need for use of intracranial electrodes.

DEVELOPMENT

SPECT and PET are most useful in cases of epilepsy with no cerebral morphological anomalies, in which there are therefore no changes which shown on MR. Cerebral SPECT with perfused tracers, such as 99mTc-HMPAO, 123I-MP or 99mTc-ECD, permit the study of patients during interictal and perictal phases. In the latter case, although the procedure is complex, one may observe an increase in cerebral blood flow in the epileptogenous focus in 90% of the patients. PET with FDG allows interictal study of patients, and shows reduced metabolism in the epileptogenic region. By comparison with video-EEG there are S = 84% and SP = 86% in temporal lobe epilepsy. The diagnostic efficiency of these two techniques is rather less in the localization of extratemporal foci and in multifocal epilepsies, although it is always better than with other diagnostic techniques. They have also been shown to be useful in the prognosis of functional recovery after surgery.

CONCLUSION

The possibility of studying neuroreceptors may be of great use in the investigation of the etiopathogenesis of epilepsy, and thus lead to improvement in the clinical and therapeutic management of patients. With SPECT, 123I-Iomacenil and 123I-lododexetimide are used. With PET and 11C-Carfentanyl opiate receptors have been studied. With 11C-Fluomacenil one may study the cerebral distribution of the benzodiazepine receptors.

[PET-FDG in thyroid cancer with high thyroglobulin levels and negative 131-I scan. A case report]

The value of whole body PET-FDG in the evaluation of metastases has been demonstrated in a wide variety of tumors. In this report, we present the case of a patient with antecedent of papillary thyroid carcinoma, who was operated twelve years ago, and submitted to an ablative dose of residual thyroid tissue through 131I, being the levels of thyroglobulin normals. After twelve years of evolution, the patient refers bag pain and respiratory trouble, appearing in the CT image suspicious of metastases in right pulmonary base. The levels of thyroglobulin were shown increased, being the 131I scan negative. A whole body PET-FDG study was performed in order to exclude metastases of his malignant process, showed multiple high FDG uptake focus in brain, cerebellum, neck, chest, lymphatic nodes and bone, suggestive of dedifferentiated disease These findings were confirmed subsequently in the clinic evolution. Therefore, whole-body PET-FDG is a complementary diagnostic technique for study patients with CDT (Thyroid Differentiated Carcinoma) with 131I scan negative and rising thyroglobulin levels.

[The role of PET-FDG in questionable diagnosis of relapse in the presence of radionecrosis of brain tumors]

INTRODUCTION

Although CT and MR are sensitive techniques for the detection of cerebral tumours, both have limitations in distinguishing between tumour relapse (TR) and post-treatment radionecrosis (RN).

PATIENTS AND METHODS

In this study we have determined the usefulness of metabolic imaging with PET-FDG in such situations. We assessed 70 patients with CNS tumours (22 low grade astrocytomas, 25 high grade astrocytomas, 3 oligodendrogliomas, 13 metastatic tumours and 7 other tumours. All had been treated with radiotherapy and other treatments such as radiosurgery, chemotherapy or different types of surgery, and presented clinical pictures which made it necessary to decide the differential diagnosis of relapse or radionecrosis.

RESULTS

In the PET-FDG study visual and semiquantitative analysis was done by SUV (Standardized Update Value). Confirmation of the findings was obtained in 44 cases (24 TR and 20 RN). MR was doubtful or inconclusive in most cases, whilst with PET correct diagnosis was made in all cases.

CONCLUSIONS

Metabolic imaging with PET-FGD is better than anatomostructural imaging techniques for differential diagnosis between tumour relapse and radionecrosis in CNS tumours which have been treated. Prospective studies are necessary for evaluation of SUV as a factor for prognosis of survival.

[Identification of the ischemic origin of dilated myocardiopathy using positron emission tomography]

INTRODUCTION AND OBJECTIVES

The aim of this study was to differentiate ischemic from nonischemic dilated cardiomyopathy with positron emission tomography. This differentiation is necessary to establish an adequate treatment, and it is often difficult with non-invasive diagnostic procedures.

METHODS

Ten patients with an echocardiographic diagnosis of dilated cardiomyopathy who had undergone coronary angiography were selected. The presence or absence of angiographic coronary lesions was used to define the ischemic (n = 6) and the nonischemic group (n = 4). The ejection fraction was depressed in both groups, with no significant differences found. A perfusion study with 13N-ammonium and a metabolic imaging with 18F-florodeoxyglucose were performed on each patient. The images were quantitatively and qualitatively analysed, defining three criteria: accumulation defect (areas with activity under 50% of the maximal radioactivity), degree of heterogeneity, and match of images with both tracers. To determinate the degree of heterogeneity, nine segments on the three standard tomographic planes were studied. Based on the following heterogeneity features: irregular borders, coexisting different degrees of accumulation, and patched accumulation, a score ranging from 0 to 3 points was assigned to these segments. To analyse the radioactivity defects and the matching of studies with both tracers, the accumulation defects or the accumulating surface were outlined on a midventricular level coronal plane.

RESULTS

The ischemic group has contrary to the nonischemic one, wider perfusion (0.26 +/- 0.21 vs 0.00) and metabolism defects (0.38 +/- 0.30 vs 0.06 +/- 0.09; p < 0.05). The degree of heterogeneity is significantly higher in the nonischemic group, either in perfusion (14.5 +/- 8.38 vs 2.5 +/- 1.04; p < 0.05) or in metabolism studies (15.5 +/- 3.31 vs 2.33 +/- 1.50; p < 0.005). Assigning wide defects and homogeneous accumulation to ischemic cardiomyopathy, and absence of defects and heterogeneous accumulation to nonischemic cardiomyopathy, the aetiology of the disease was identified in 9 of the 10 cases in the perfusion study and 100% of them with the metabolism imaging.

CONCLUSIONS

Positron emission tomography allows to identify the aetiology of dilated cardiomyopathy, either with coronary perfusion or with myocardial glucose metabolism studies. Thus, only one of both PET studies could be used. Ischemic cardiomyopathy is characterised by wide defects and homogeneous radioactivity, and the nonischemic one by the absence of defects and heterogeneous accumulation of the tracer.

Cerebral perfusion, electrical activity and effects of serotonergic treatment in obsessive-compulsive disorder. A preliminary study

An abnormally increased glucose metabolism has been described with positron emission tomography (PET) in frontal and caudate regions of obsessive-compulsive patients. Perfusion and electroencephalographic studies have been less conclusive. However, these techniques are, currently, more available than PET and, therefore, deserve further study because of their possible clinical applications. In this article, 13 obsessive-compulsive patients were studied with quantitative EEG and auditory and visual evoked potentials. Six of them were studied also with perfusion single photon emission tomography. A group of 4 patients was studied with both techniques before and after a serotonergic treatment. Increased global, beta, and theta electrical power together with an increased perfusion in frontal regions was observed. The patients also showed a delta power increase over right temporal and frontal regions, together with increased perfusion in the right basal ganglia region as well as a decreased amplitude of the P50 and N100 waves of the auditory evoked potentials over temporal electrodes; these alterations were reduced with treatment. These results are discussed in the context of current data about serotonergic neurotransmission.

Zinc in hypothalamus and hypophysis of the rat

Zinc has been located using both histochemical and autoradiographic procedures in the neurons of the nuclei of the hypothalamic medial area and in some adenohypophisary cells. Some suggestions about the functional significance of the presence of Zn in these places are made.

[Pulmonary gammagraphy in children with cystic fibrosis]

An analysis is carried out of the findings from the radioisotopic lung scans of 16 children suffering from cystic fibrosis (CF), 10 boys and 6 girls, with an age range of between 3.5 and 14.2 years and an evolution time of between 1.2 and 9.9 years. The radioisotopic lung scan study shows lung perfusion defects in 14 of the 16 children (87%), the pulmonary vertices being more greatly affected, especially in the left lung (81%). We revised current aspects of radioisotopic lung scanning in paediatrics and evaluated the great importance of this test as a means of detecting CF and its evolution.