PET-CT derived Artificial Neural Network can predict mediastinal lymph nodes metastases in Non-Small Cell Lung Cancer patients. Preliminary report and scoring model

AIM

Mediastinal lymph nodes staging in NSCLC (non small cell lung cancer) is of undisputable importance. Although relatively precise, diagnostic modalities, mediastinoscopy and EBUS/EUS - TBNA (endobronchial/endoscopic ultrasound guided--transbronchial needle aspiration) still employ certain level of invasiveness. Artificial Neural Network (ANN) is an established predictor tool which, due to underlying distribution and relationship among the given variables, allow for construction of multidimensional models trained in prognosis of given outcome. Their performance in mediastinal staging based on radiological data only, remains limited to single studies.

METHODS

We obtained 467 groups of lymph nodes from 160 patients with primary NSCLC by means of EBUS--TBNA, mediastinoscopy or lymphadenectomy during thoracotomy and analyzed them microscopically. ANN models were created and prospectively validated on unmatched cohort of 50 consecutive patients (158 groups of lymph nodes). To identify factors correlated with nodal involvement single factor tests and logistic regression analyzes were performed. Additionally, logistic regression analysis allowed for construction of scoring model with certain parameters corresponding to risk thresholds of metastatic disease.

RESULTS

Size and standard uptake value (SUV) of the node along with primary tumour T characteristics were identified as the most sensitive variables regardless of the analysis conducted. Two ANN models predicted metastatic involvement with 89% and 92% accuracy. Single factor tests maintained high accuracy only for 2 out of 4 most sensitive variables (SUV >2.8 and length >15mm) in prospective validation.

CONCLUSIONS

ANN is a repeatable and accurate diagnostic tool in mediastinal staging in NSCLC patients. Before its role in clinical practice will be established in large multi--centre study, findings of this preliminary report should be considered as exploratory only.

The role of positron emission tomography (PET) in diagnostics of gastroenteropancreatic neuroendocrine tumours (GEP NET)

PET is a successful modality to detect cancer and in recent years has demonstrated a great diagnostic value in large series of tumour types. PET combines high sensitivity and reasonable resolution, and offers the ability to perform whole body scans. 18F-deoxyglucose (FDG)-PET has also been used to diagnose tumours of neuroendocrine origin. Even if 18F-FDG has been successfully and widely employed in oncology, it has not demonstrated a significant uptake in well differentiated neuroendocrine tissues. Thus 18F-FDG is not a good tracer for neuroendocrine tumours, as FDG-PET imaging of number of GEP tumours revealed increased glucose metabolism only in less differentiated GEP tumours with high proliferative activity and in metastatising MTC associated with rapidly increasing CEA levels. In such a situation, additional 18F-FDG PET should be performed only if somatostatin receptor scintigraphy (alone or with 99mTc-DMSA) is negative. On the contrary, other positron emitter tracers seem to be more promising. 68Ga-DOTA-NOC (tetraazycyclododecanetetraacetic acid-[1-Nal3]-octreotide) has been used as a positron emitter tracer for the detection of NETs in preliminary studies. A serotonin precursor 5-hydroxytryptophan (5-HTP) labelled with 11C has shown an increased uptake in carcinoids. This uptake seems to be selective and some clinical evidence has demonstrated that it allows the detection of more lesions with PET than with CT or octreotide scintigraphy. Another radiopharmaceutical in the development for PET is 11C-L-DOPA, which seems to be useful in imaging endocrine pancreatic tumours.

[Correlation between results of transcranial doppler ultrasonography and SPECT in the brain of patients with ischemic cerebral stroke]

Single photon emission computerized tomography /SPECT/ and positron emission tomography /PET/ are used presently for the study of the cerebral blood flow /CBF/. The cost of these procedures limits the possibility of their use and makes them available mainly in large and rich clinical centres. Transcranial Doppler USG has no such drawbacks. The purpose of the present study was analysis of a possible correlation between marker cumulation /in SPECT/ in the vascularization area of the middle cerebral artery /MCA/ and the parameters Vs, Vm, Vd, PI, RI, R of the PUSG-G examination of these arteries in 50 patients aged 48-79 years treated for ischaemic cerebral episodes. Brain SPECT examination was done with Apex-SP-6-HR gamma camera assessing the distribution of 99mTc HMPAO marker in the vascularization area of both MCA. PUSG-D examination was done with Tc-2-64 unit. In both MCA the systolic Vs, the mean velocity Vm, the diastolic velocity Vd, the Gosling pulsation index PI, the Purcelot resistance index RI and the velocity amplitude R were measured. The following conclusions have been reached: 1/ in patients with ischaemic cerebral episodes a significant correlation was found between cerebral SPECT findings and the PUSG-D parameters; 2/ reduced perfusion of the cerebral tissue was correlated with lower values of Vs, Vm, Vd, and R and with higher values of PI and RI; 3/ slight disturbances of perfusion found in SPECT were not reflected in changed PUSG-D parameters; 4/ the results justify the use of PUSG-D for indirect assessment of blood flow in the MCA.

[The significance of radioisotopic methods in internal diseases diagnosis]

The present article is an attempt to show the best diagnostic radioisotopic methods which are practically applied in the internal diseases diagnostics. It was shown both the most important indications for performing these examinations and expected advantages. In particular, it was paid attention to achieved progress in the diagnostics of some diseases owing to radioisotopic methods application. In addition, a general availability and non-invasity of these methods advocates in support of using them.

[The significance of scintigraphic, echocardiographic and electrocardiographic left atrial transesophageal pacing in diagnosis of ischemic heart disease]

The aim of the study was to compare the perfusion scintigraphy (using SPECT method with Tc-99-MIBI) during left atrial transoesophageal pacing test (LAPT) with pacing electrocardiography (ECG), echocardiography (ECHO) and electrocardiography exercise test (ExT) in ischaemic heart disease (IHD) diagnostics. The effect of LATP on heart haemodynamic parameters and the correlation between scintigraphic, echocardiographic and electrocardiographic parameters during LAPT test have been also assessed. Investigations were carried out in 55 subjects (Group I: 36 patients with effort angina pectoris; group II: controls: 19 clinically healthy subjects). Coronarography was performed in 24 patients 6 weeks before or after examinations. LATP test was analyzed with ECG, ECHO and SPECT. Echocardiography did not increase significantly the LATP test diagnostic value. Perfusion scintigraphy enhanced sensitivity and predictive excluding value LATP test. These values were 93.3% v 62.9% and 90% v 59.3% respectively. LATP test assessed with ECG, ECHO and perfusion scintigraphy expressed significantly higher sensitivity and predicting excluding value in comparison to ExT. LATP test analyzed in such way was characterized by 100% sensitivity and 100% predicting excluding value.

CONCLUSION

Combination of LATP with electrocardiography, echocardiography and SPECT is a non-invasive high quality method for ischaemic heart disease diagnostics.