Joanna Mączewska

Assessment of inflow and washout of indocyanine green in the adult human brain by monitoring of diffuse reflectance at large source-detector separation.

Recently, it was shown in measurements carried out on humans that time-resolved near-infrared reflectometry and fluorescence spectroscopy may allow for discrimination of information originating directly from the brain avoiding influence of contaminating signals related to the perfusion of extracerebral tissues. We report on continuation of these studies, showing that the near-infrared light can be detected noninvasively on the surface of the tissue at large interoptode distance. A multichannel time-resolved optical monitoring system was constructed for measurements of diffuse reflectance in optically turbid medium at very large source-detector separation up to 9 cm. The instrument was applied during intravenous injection of indocyanine green and the distributions of times of flight of photons were successfully acquired showing inflow and washout of the dye in the tissue. Time courses of the statistical moments of distributions of times of flight of photons are presented and compared to the results obtained simultaneously at shorter source-detector separations (3, 4, and 5 cm). We show in a series of experiments carried out on physical phantom and healthy volunteers that the time-resolved data acquisition in combination with very large source-detector separation may allow one to improve depth selectivity of perfusion assessment in the brain.

Time-resolved detection of fluorescent light during inflow of ICG to the brain?a methodological study

It was reported that time-resolved reflectance measurements carried out during inflow and washout of an optical contrast agent may provide information on the blood supply to the brain cortex of human adults. It was also shown that a measurement of fluorescence excited in the dye circulating in the brain is feasible. Unfortunately, patterns of time-resolved fluorescence signals observed during in vivo measurements are difficult to interpret. The aim of this study was to analyze the influence of several factors on the fluorescence signals measured during in vivo experiments. A laboratory instrument for recording the distributions of arrival of fluorescence photons was constructed and optimized for measurements on humans. Monte Carlo simulations and laboratory measurements on liquid phantoms as well as in vivo measurements on healthy volunteers were carried out. An influence of source-detector separation, position of the source-detector pair on the head, as well as a dose of the injected indocyanine green (ICG) on the fluorescence signals were studied in detail. It was shown that even for a small dose of ICG (0.025 mg kg(-1)) the time-resolved signals can be successfully detected on the surface of the head. Strong influence of the studied factors on the fluorescence signals was observed. It was also noted that the changes in moments of distributions of arrival times of fluorescence photons depend on the anatomical structure of the tissues located between the source and the detector.

Myocardial viability assessment in 18FDG PET/CT study (18FDG PET myocardial viability assessment).

Accurate identification of viable myocardium is crucial in patient qualification for medical or surgical treatment. Only persons with confirmed cardiac viability will benefit from revascularization procedures. It is also well known, that the amount of viable myocardium assessed preoperatively is the best indicator of long term cardiac event free survival after cardiac intervention.There are several diagnostic approaches used in current clinical practice for assessment of myocardial viability. Analysis of wall thickness or myocardial contraction, evaluation of cardiac perfusion or metabolism can be assessed using following modalities: Echocardiography, Cardiac Molecular Imaging techniques (PET, SPECT), Cardiovascular MR or Cardiovascular CT. The article describes the methods and problems of viability assessment in 18FDG PET study. PET imaging has proved its accuracy and reproducibility for myocardial ischemia and viability assessment. However this unique in its ability for showing the particular substrate metabolism technique has unfortunately some disadvantages: currently achieved PET resolution is 0.4 cm. However the combined devices multislice computed tomography scanners with PET (PET/CT) are now widely used in clinical practice. This combination allows for wider morphologic assessments: coronary calcium scoring and non-invasive coronary angiography may be added to myocardial perfusion/metabolic imaging if necessary.

Simplified protocol of cardiac 18F-fluorodeoxyglucose positron emission tomography viability study in normoglycemic patients with known coronary artery disease ☆

PURPOSE The purpose was to evaluate quality of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) myocardial scans and its correlation with background glucose (BG) after simplified 5% intravenous glucose load protocol. METHODS An intravenous glucose load protocol was applied in 69 normoglycemic patients with confirmed coronary artery disease. The blood glucose level was measured every 15 min. RESULTS Eighty-four percent of images were optimal, 8.7% suboptimal, and 7.3% uninterpretable. The quality of 18F-FDG-PET was BG independent and body mass index dependent (P=.0007). CONCLUSIONS Simplified glucose load protocol is a safe and efficient method of preparation for FDG cardiac viability study in patients with normoglycemia.

Assessment of the myocardial FDG-PET image quality with the use of maximal Standardized Uptake Value myocardial to background index. Application of the results in regard to semiquantitative assessment of myocardial viability with cardiac dedicated softwar

BACKGROUND The objective of this study was to semiquantitatively assess the degree of myocardial fluorodeoxyglucose (FDG) uptake in glucose-loaded myocardial viability positron emission tomography/computed tomography (PET/CT) scans, to calculate the myocardial to background index, and correlate the index with image quality assessed on the basis of visual qualitative assessment. MATERIAL AND METHODS The myocardial FDG-PET/CT study was carried out in 69 non-diabetic patients, who had known coronary artery disease, by intravenous injection of 250 ± 70 MBq (range: 180-320 MBq) FDG. Images were interpreted visually and patients were divided into three groups according to the grade of myocardial uptake: optimal, suboptimal, and uninterpretable. Semiquantitative analysis was performed by calculating the standardized uptake value (SUVmax) for myocardium and background (blood pool) activity, and expressed as the myocardial to background (M/B) activity ratio. RESULTS On the basis of visual (qualitative) analysis, 60/69 (86.96%) patients showed optimal quality of FDG cardiac uptake, 3/69 (4.35%) were suboptimal, and uninterpretable FDG PET scan results were found in 6/69 (8.70%) patients. The M/B index was found to be significantly higher in images of optimal vs. suboptimal quality (6.87 ± 3.99 vs. 1.65 ± 0.78 respectively; p < 0.0001). CONCLUSIONS The index ratio of 2.2, which is consistent with the upper borderline value for visually uninterpretable images, was considered the cut-off value for scans of optimal and non-optimal quality.

Computer program for analysis of parathyroid scintigraphy examinations: combination of dual-tracer (subtraction) and double phase single-tracer washout techniques.

There is no controversy in the published literature that sensitivity and specificity of parathyroid scintigraphy is superior to other imaging techniques. However no uniform protocol has been established for scintigraphy. In order to analyze parathyroid scintigraphic images in the Department of Nuclear Medicine at the Medical University of Warsaw we have developed a program that allows qualitative and quantitative evaluation of recorded images and motion artifacts correction. This program offers a uniform procedure of analysis of parathyroid imaging results in diagnostic centers, accelerates the analysis of parathyroid tests performed with use of single radioactive tracer, that require the acquisition of consecutive images of the patient, without altering his body position between successive stages of registration. This program allows for automation of previously time consuming procedures and thus saves time and decreases a risk of operators errors.

Korelacja nasilenia zmian zapalnych błony śluzowej zatok przynosowych w ocenie tomografią komputerową i tkanki kostnej błędnika sitowego w ocenie tomografią emisyjną pojedynczych fotonów SPECT u pacjentów z przewlekłym zapaleniem zatok przynosowych

Summary Osteitis has been proven to play important role in patophysiology of chronic rhinosinusitis (CRS). Computed tomography (CT), a standard diagnostic technique used to evaluate the extent of the sinus disease, fails to show the bone involvement in patients with CRS. In contrast single-photon emission tomography (SPECT) yields adequate information on remodeling and bone turnover. Persistent osteitis may be one of the reasons of failure of adequate medical and surgical therapy for CRS and discrepancies between extent of the disease as evaluated by CT and symptom scores. The aim of the study is to evaluate correlation between the results of CT and SPECT in patients with CRS. Material and methods 29 patients with CRS (15 with nasal polyps and 14 without nasal polyps) were evaluated with CT and SPECT. The mucosal involvement of CRS graded on Lund-Mackay Scale (LMS) was compared to degree of bone involvement evaluated by SPECT with the use of modified LMS. Results The mean LMS grade was 13,3 for CT and 9,8 for SCPECT (modified LMS). A positive correlation between the results of two imaging methods was found r = 0,72 (p Conclusions The bone involvement as evaluated by SPECT correlates with the degree of mucosal changes showed by CT.UNLABELLED Osteitis has been proven to play important role in patophysiology of chronic rhinosinusitis (CRS). Computed tomography (CT), a standard diagnostic technique used to evaluate the extent of the sinus disease, fails to show the bone involvement in patients with CRS. In contrast single-photon emission tomography (SPECT) yields adequate information on remodeling and bone turnover. Persistent osteitis may be one of the reasons of failure of adequate medical and surgical therapy for CRS and discrepancies between extent of the disease as evaluated by CT and symptom scores. THE AIM OF THE STUDY is to evaluate correlation between the results of CT and SPECT in patients with CRS. MATERIAL AND METHODS 29 patients with CRS (15 with nasal polyps and 14 without nasal polyps) were evaluated with CT and SPECT. The mucosal involvement of CRS graded on Lund-Mackay Scale (LMS) was compared to degree of bone involvement evaluated by SPECT with the use of modified LMS. RESULTS The mean LMS grade was 13,3 for CT and 9,8 for SCPECT (modified LMS). A positive correlation between the results of two imaging methods was found r = 0.72 (p < 0.0001). CONCLUSIONS The bone involvement as evaluated by SPECT correlates with the degree of mucosal changes showed by CT.

Transcranial Time-resolved Measurements of Fluorescence of an Exogeneous Dye Circulating in Human Brain

Time-resolved imager was used for monitoring of inflow of exogenous dye into the brain. We observed variation of fluorescence signals caused by changes of dose of the dye and position of optode on the head