Nuclear Medicine Data Research Articles

Unambiguous radiologic extranodal extension determined by MRI could be a biomarker in predicting metastatic prostate cancer

To explore the relationship between unambiguous radiologic extranodal extension (rENE) and M1 staging in patients with metastatic PCa. A respective analysis of 1073 patients of PCa N1 staging from January 2004 to May 2022 was retrospectively enrolled. They were divided into rENE + and rENE - groups and retrospectively analyzed the M staging with nuclear medicine data. The correlation index between unambiguous rENE and M1b staging was calculated. Logistic regression was used to evaluate the predictive performance of unambiguous rENE in M1b staging. ROC curves were used to investigate the relationship between unambiguous rENE and M staging in patients who underwent 68Ga-PSMA PET/CT. A total of 1073 patients were included. Seven hundred and eighty patients were classified into the rENE + group (mean age, 69.6years ± 8.7 [standard deviation]), and 293 were classified into rENE - group (mean age, 66.7years ± 9.4 [standard deviation]). Relationship between unambiguous rENE and M1b existed (r = 0.58, 95%CI: 0.52-0.64, P < 0.05). Unambiguous rENE could be an independent predictor for M1b (OR = 13.64, 95%CI: 9.23-20.14, P < 0.05). The AUC of unambiguous rENE in predicting M1b and M staging was 0.835 and 0.915, respectively, in patients who underwent 68Ga-PSMA PET/CT. Unambiguous rENE could be a strong biomarker to predict M1b and M staging in patients with PCa. When rENE came up, patients should perform nuclear medicine immediately, and a systematic treatment should be considered.

Perfil Clínico, Laboratorial e de Métodos de Imagem na Amiloidose Sistêmica em um Centro de Referência Cardiológico Brasileiro

ResumoFundamento Amiloidose sistêmica é uma doença com manifestações clínicas diversas. O diagnóstico envolve suspeita clínica, aliada a métodos complementares.Objetivo Descrever o perfil clínico, laboratorial, eletrocardiográfico e de imagem no acometimento cardíaco da amiloidose sistêmica.Métodos Estudo de uma amostra de conveniência, analisando dados clínicos, laboratoriais, eletrocardiográficos, ecocardiográficos, medicina nuclear e ressonância magnética. Considerou-se significância estatística quando p < 0,05.Resultados Avaliaram-se 105 pacientes (com mediana de idade de 66 anos), sendo 62 homens, dos quais 83 indivíduos apresentavam amiloidose por transtirretina (ATTR) e 22 amiloidose por cadeia leve (AL). Na ATTR, 68,7% eram de caráter hereditário (ATTRh) e 31,3% do tipo selvagem (ATTRw). As mutações mais prevalentes foram Val142Ile (45,6%) e Val50Met (40,3%). O tempo de início dos sintomas ao diagnóstico foi 0,54 e 2,15 anos nas formas AL e ATTR (p < 0,001), respectivamente. O acometimento cardíaco foi observado em 77,9% dos ATTR e 90,9% dos AL. Observaram-se alterações de condução atrioventricular em 20% e intraventricular em 27,6% dos pacientes, sendo 33,7 % na ATTR e 4,5% das AL (p = 0,006). A forma ATTRw apresentou mais arritmias atriais que os ATTRh (61,5% x 22,8%; p = 0,001). Ao ecocardiograma a mediana da espessura do septo na ATTRw x ATTRh x AL foi de 15 mm x 12 mm x 11 mm (p = 0,193). Observou-se BNP elevado em 89,5% dos indivíduos (mediana 249 ng/mL, IQR 597,7) e elevação da troponina em 43,2%.Conclusão Foi possível caracterizar, em nosso meio, o acometimento cardíaco na amiloidose sistêmica, em seus diferentes subtipos, através da história clínica e dos métodos diagnósticos descritos.

A Brief History of Nuclear Medicine Physics, Instrumentation, and Data Sciences in Korea.

We review the history of nuclear medicine physics, instrumentation, and data sciences in Korea to commemorate the 60th anniversary of the Korean Society of Nuclear Medicine. In the 1970s and 1980s, the development of SPECT, nuclear stethoscope, and bone densitometry systems, as well as kidney and cardiac image analysis technology, marked the beginning of nuclear medicine physics and engineering in Korea. With the introduction of PET and cyclotron in Korea in 1994, nuclear medicine imaging research was further activated. With the support of large-scale government projects, the development of gamma camera, SPECT, and PET systems was carried out. Exploiting the use of PET scanners in conjunction with cyclotrons, extensive studies on myocardial blood flow quantification and brain image analysis were also actively pursued. In 2005, Korea's first domestic cyclotron succeeded in producing radioactive isotopes, and the cyclotron was provided to six universities and university hospitals, thereby facilitating the nationwide supply of PET radiopharmaceuticals. Since the late 2000s, research on PET/MRI has been actively conducted, and the advanced research results of Korean scientists in the fields of silicon photomultiplier PET and simultaneous PET/MRI have attracted significant attention from the academic community. Currently, Korean researchers are actively involved in endeavors to solve a variety of complex problems in nuclear medicine using artificial intelligence and deep learning technologies.

Development and Validation of a Semi-Automated, Preclinical, MRI-Template Based PET Image Data Analysis Tool for Rodents.

AimIn PET imaging, the different types of radiotracers and accumulations, as well as the diversity of disease patterns, make the analysis of molecular imaging data acquired in vivo challenging. Here, we evaluate and validate a semi-automated MRI template-based data analysis tool that allows preclinical PET images to be aligned to a self-created PET template. Based on the user-defined volume-of-interest (VOI), image data can then be evaluated using three different semi-quantitative parameters: normalized activity, standardized uptake value, and uptake ratio.Materials and MethodsThe nuclear medicine Data Processing Analysis tool (NU_DPA) was implemented in Matlab. Testing and validation of the tool was performed using two types of radiotracers in different kinds of stroke-related brain diseases in rat models. The radiotracers used are 2-[18F]fluoro-2-deoxyglucose ([18F]FDG), a metabolic tracer with symmetrical distribution in brain, and [68Ga]Ga-Fucoidan, a target-selective radioligand specifically binding to p-selectin. After manual image import, the NU_DPA tool automatically creates an averaged PET template out of the acquired PET images, to which all PET images are then aligned onto. The added MRI template-based information, resized to the lower PET resolution, defines the VOI and also allows a precise subdivision of the VOI into individual sub-regions. The aligned PET images can then be evaluated semi-quantitatively for all regions defined in the MRI atlas. In addition, a statistical analysis and evaluation of the semi-quantitative parameters can then be performed in the NU_DPA tool.ResultsUsing ischemic stroke data in Wistar rats as an example, the statistical analysis of the tool should be demonstrated. In this [18F]FDG-PET experiment, three different experimental states were compared: healthy control state, ischemic stroke without electrical stimulation, ischemic stroke with electrical stimulation. Thereby, statistical data evaluation using the NU_DPA tool showed that the glucose metabolism in a photothrombotic lesion can be influenced by electrical stimulation.ConclusionOur NU_DPA tool allows a very flexible data evaluation of small animal PET data in vivo including statistical data evaluation. Using the radiotracers [18F]FDG and [68Ga]Ga-Fucoidan, it was shown that the semi-automatic MRI-template based data analysis of the NU_DPA tool is potentially suitable for both metabolic radiotracers as well as target-selective radiotracers.

Ревматическая полимиалгия в клинических рекомендациях 2018–2020 гг. Часть II: диагностика васкулита

Совершенствование диагностики ревматических болезней пожилых людей и заболеваний аорты— актуальные задачи медицины. В патогенезе аневризм, расслоений, разрывов аорты важна роль воспаления и структурных изменений ее стенки, которые выявляют с помощью визуализирующих методов. Ведению ревматической полимиалгии, гигантоклеточного артериита, аневризм аорты посвящен ряд международных рекомендаций. С аортитом сопряжено до 40% случаев ревматической полимиалгии. Клиническое подозрение на него основано на выявлении асимметрии артериального давления и пульса, шума аортальной регургитации, сосудистых шумов, персистенции ревматической полимиалгии, воспалительной боли в спине, области таза и нижних конечностях. В 2020 году именно позитронно-эмиссионная томография/компьютерная томография рекомендована Итальянским обществом ревматологов для диагностики васкулита при ревматической полимиалгии во вторичном звене и Европейской федерацией головной боли для диагностики крупнососудистого гигантоклеточного артериита в неврологической практике. Приведен обзор рекомендаций Европейской ассоциации ядерной медицины, Общества ядерной медицины и молекулярной визуализации и Американского общества ядерной кардиологии по применению позитронно-эмиссионной томографии с фтордеоксиглюкозой в сочетании с компьютерной томографией (ангиографией) при васкулитах крупных сосудов и ревматической полимиалгии (2018). Они сопоставлены с клиническими руководствами, другими рекомендациями обществ ядерной медицины и новыми научными данными. Описана процедура исследования и подготовка к нему. Рассмотрены критерии оценки васкулита, предложенные для клинической практики и для клинических исследований, а также факторы, влияющие на результаты теста и их интерпретацию (атеросклероз, диабет, возраст, индекс массы тела, уровни гликемии и маркеров острой фазы). В рекомендациях обоснована польза применения позитронно-эмиссионной томографии и ее сочетания с компьютерной томографией для выявления экстракраниального васкулита и ценность компьютерной томографии-ангиографии на разных стадиях болезни. Требует усиления доказательная база стандарта времени экспозиции фтордеоксиглюкозы и пользы сочетания позитронной эмиссионной томографии с компьютерной томографией-ангиографией, в том числе для выявления рецидивов васкулита и мониторинга терапии. Необходим консенсус по раннему выполнению исследования, стандартизация оценок его результатов, обеспечение реимбурсации, внедрение новых методик визуализации сосудов черепа. В перспективе доказательный подход к ведению васкулита дополнит терагностика.

A Regularized Affine-Scaling Trust-Region Method for Parametric Imaging of Dynamic PET Data

Parametric imaging of nuclear medicine data exploits dynamic functional images in order to reconstruct maps of kinetic parameters related to the metabolism of a specific tracer injected in the biological tissue. Classical approaches to parametric imaging rely on linearized schemes that, on the one hand, are computationally effective but, on the other hand, provide information just on a very limited number of parameters (typically two). Possible nonlinearized approaches require the pixelwise numerical solution of compartmental nonlinear ill-posed inverse problems and therefore typically imply a notable computational burden. In the present paper we introduce a fast numerical optimization scheme for parametric imaging relying on a regularized version of the standard affine-scaling trust-region method. The main advantages of this approach are both that it is a regularization method (and therefore it reduces the numerical instabilities in the reconstructed images) and that it is significantly faster than other algorithms in the optimization market (and therefore it may be utilized for clinical applications). The validation of this approach is realized in a simulation framework for brain imaging and also in the case of an experimental set of nuclear medicine data acquired from a murine model. Comparison of performances is made with respect to a regularized Gauss--Newton scheme and a standard nonlinear bound-constrained least-squares algorithm.

The Value of Data Mining Technology in the Diagnosis of Bone Metastases from Prostate Cancer Based on Nuclear Medicine Image

With the continuous development of information construction in the medical industry, a large amount of data related to bone metastasis of prostate cancer can be found in the medical database. It includes a large number of inspection indicators, medical images, and background information such as gender, age, height, weight, and previous medical history. The content is very rich and detailed. The nuclear medicine image processing technology and data mining technology are organically combined to study the feature extraction and loading method of nuclear medicine image data, and the classification method of medical image data, thereby assisting doctors in decision-making diagnosis process and improving accuracy. These have important theoretical significance and broad application prospects. Therefore, based on the nuclear medicine imaging data, this study utilized data mining technology to analyse the nuclear medical imaging data of prostate cancer bone metastasis, and finds and summarizes the imaging features and developmental rules of prostate cancer bone metastasis. So, a BP neural network diagnosis matrix for prostate cancer bone metastasis was constructed. This is valuable and meaningful for the diagnosis, treatment and even medical research of bone metastasis of prostate cancer.

Does Ct volumetry accurately predict functional reserve of the future liver remnant after major hepatectomy?

Background: Precise quantitative tests are not available to measure synthetic liver function prior to major hepatectomy. Most centers rely on imperfect surrogates including laboratory studies and CT volumetry. Indocyanine green clearance can quantify functional hepatocyte mass, but does not provide regional assessment and has not been widely adopted in North America. Nuclear medicine tests are rarely used for preoperative planning, but are an additional option to asses overall, hemi-liver, and segmental hepatic function. The purpose of this study was to compare CT volumetry with functional nuclear medicine testing as an accurate measure to predict hepatic function of the future liver remnant. Methods: CT volumetry and functional nuclear medicine data were collected prospectively for patients undergoing evaluation for hepatocellular carcinoma (HCC) from February 2016-May 2018. Paired CT and nuclear medicine scans were obtained within 9 months (median 1 month) of one another. Nuclear medicine scans were performed with freshly prepared technetium 99m labeled mebrofenin (an iminodiacetic analogue), initially dynamic planar images were acquired and thereafter a single-photon emission computed tomography (SPECT) scan was performed. Total and regional liver volumes were calculated and reported by an attending radiologist. Extent of discrepancy between modalities was calculated. Clinical and demographic characteristics including the extent of chronic liver disease were recorded. Results: Over 27 months, 63 patients with HCC underwent both CT and functional nuclear medicine imaging. Median age was 64 years (range 25–85 yrs). Fifty patients (74.6%) were classified as cirrhotic. Of the cirrhotic patients, 60% (n = 30) had Child’s A, 38% Child's B (n = 19) and 2% Child's C cirrhosis (n = 1). Standard CT volumetry overestimated total functional liver volume, TLV, (median 1508 ml; range 570.2–4112.9 ml) when compared with functional nuclear medicine scan (median 1320 ml; range 6.9–3546.1 ml; p = 0.02). Significant discrepancy existed between regional liver volumes and percent contribution to hepatic function. The median volume of the right hemi-liver by CT volumetry was 906 ml (range 187–2324; 61% of TLV) and 721 ml by functional nuclear medicine study (range 12–2050; 65% of TLV; p = 0.03). Less discrepancy was found between left hemi-liver measurements: median volume by CT volumetry was 591 ml (range 100–2236; 38% of TLV) and 512 ml by functional nuclear medicine scan (range 69–2050; 35% of TLV; p = 0.21). Median discrepancy in hemi-liver volumes was 4.8% (range 0.2–51.5%) for the right, and 4.7% (0.2–51.5%) for the left hemi-liver. More than half of the patients (n = 34) had less than 5% discrepancy in hemi-liver volumes, 10 had 5–10% discrepancy, 11 had 10–20% discrepancy. Eight patients (12%) had volume discrepancies greater than 20% between CT volumetry and nuclear medicine imaging. Conclusion: Significant discrepancy exists between standard CT volumetry and nuclear medicine SPECT for estimating functional liver volumes. Compared with functional nuclear medicine imaging, CT volumetry appears to overestimate liver volume. Functional nuclear medicine scans provide additional information and may be a useful and affordable tool for preoperative assessment of the future liver remnant when planning major hepatectomy.

Compartmental analysis of dynamic nuclear medicine data: regularization procedure and application to physiology

ABSTRACTCompartmental models based on tracer mass balance are extensively used in clinical and pre-clinical nuclear medicine in order to obtain quantitative information on tracer metabolism in the biological tissue. This paper is the second of a series of two that deal with the problem of tracer coefficient estimation via compartmental modelling in an inverse problem framework. While the previous work was devoted to the discussion of identifiability issues for 2, 3 and n-dimension compartmental systems Delbary et al. [Compartmental analysis of dynamic nuclear medicine data: models and identifiability. Inverse Probl. 2016], here we discuss the problem of numerically determining the tracer coefficients by means of a general regularized Multivariate Gauss–Newton scheme. In this paper, applications concerning cerebral, hepatic and renal functions are considered, involving experimental measurements on FDG–PET data on different set of murine models.

Acute Kidney Injury Following Methimazole Initiation: A Case Report

Objective: Nephritis has been rarely associated with methimazole, primarily in the development of nephrotic syndrome. We describe a case of acute kidney injury without evidence of nephrotic syndrome following methimazole initiation. Methods: We present the relevant history, laboratory data, and nuclear medicine data and review relevant documentation from the literature. Results: A 72-year-old male recently diagnosed with new-onset atrial fibrillation was found to have suppressed thyroid-stimulating hormone (TSH) levels; elevated free T3, T4, and thyroid-stimulating immunoglobulin (TSI) levels; and a nonnodular thyroid gland with normal iodine uptake. He was diagnosed with Graves’ disease and treated with propylthiouracil (PTU) for 5 years. When his poor compliance with PTU was impeding his antithyroid treatment, he was converted to methimazole. Within 1 month following methimazole initiation, his serum creatinine (SCr) had risen to 1.6× baseline in the absence of other contributing nephrotoxins. SCr returned to baseline within 2 weeks of methimazole discontinuation, and the patient was subsequently managed on PTU. Conclusion: Acute kidney injury with or without the presence of nephrotic syndrome may occur during treatment with methimazole. Renal function should be closely monitored after the initiation of methimazole to prevent progressive renal dysfunction.

PATIENT EXPOSURE FROM NUCLEAR MEDICINE IN FRANCE: NATIONAL FOLLOW-UP AND INFLUENCE OF THE TECHNOLOGY THROUGH DIAGNOSTIC REFERENCE LEVELS DATA ANALYSIS.

The Nuclear Safety and Radiation Protection French Institute (IRSN) presents its latest assessment from up-to-date diagnostic reference levels (DRL) national data in nuclear medicine (NM). NM departments annually send data to IRSN to estimate the representativeness of current DRLs. Complementary analyses of the data have been performed to evaluate the influence of equipment evolution on practice and patient radiation exposure. Based on data from almost 90% of the French NM departments, some DRL update are proposed. The analysis of positron emission tomography data show that the more the time of flight technology is available on equipment, the lower is the administered activity to the patient. IRSN recommends updating DRL regulation with current and relevant examination data. The influence of technology evolution appeared to be positive for patient exposure and the results showed an obvious involvement of professionals in the radiation dose optimisation process.

Compartmental analysis of dynamic nuclear medicine data: models and identifiability

Compartmental models based on tracer mass balance are extensively used in clinical and pre-clinical nuclear medicine in order to obtain quantitative information on tracer metabolism in the biological tissue. This paper is the first of a series of two that deal with the problem of tracer coefficient estimation via compartmental modelling in an inverse problem framework. Specifically, here we discuss the identifiability problem for a general n-dimension compartmental system and provide uniqueness results in the case of two-compartment and three-compartment compartmental models. The second paper will utilize this framework in order to show how nonlinear regularization schemes can be applied to obtain numerical estimates of the tracer coefficients in the case of nuclear medicine data corresponding to brain, liver and kidney physiology.

A New Pulse Pileup Rejection Method Based on Position Shift Identification.

Pulse pileup events degrade the signal-to-noise ratio (SNR) of nuclear medicine data. When such events occur in multiplexed detectors, they cause spatial misposition, energy spectrum distortion and degraded timing resolution, which leads to image artifacts. Pulse pileup is pronounced in PETbox4, a bench top PET scanner dedicated to high sensitivity and high resolution imaging of mice. In that system, the combination of high absolute sensitivity, long scintillator decay time (BGO) and highly multiplexed electronics lead to a significant fraction of pulse pileup, reached at lower total activity than for comparable instruments. In this manuscript, a new pulse pileup rejection method named position shift rejection (PSR) is introduced. The performance of PSR is compared with a conventional leading edge rejection (LER) method and with no pileup rejection implemented (NoPR). A comprehensive digital pulse library was developed for objective evaluation and optimization of the PSR and LER, in which pulse waveforms were directly recorded from real measurements exactly representing the signals to be processed. Physical measurements including singles event acquisition, peak system sensitivity and NEMA NU-4 image quality phantom were also performed in the PETbox4 system to validate and compare the different pulse pile-up rejection methods. The evaluation of both physical measurements and model pulse trains demonstrated that the new PSR performs more accurate pileup event identification and avoids erroneous rejection of valid events. For the PETbox4 system, this improvement leads to a significant recovery of sensitivity at low count rates, amounting to about 1/4th of the expected true coincidence events, compared to the LER method. Furthermore, with the implementation of PSR, optimal image quality can be achieved near the peak noise equivalent count rate (NECR).

Visual Perception in Nuclear Medicine and Volumetric Data

Any diagnostic decision that involves imaging techniques depends not entirely on the images themselves but also on the perception and interpretation by a radiologist. In fact, such human factors appear to be a bottleneck to imaging accuracy. A better understanding of visual perception and decision-making processes seem to be necessary for the advancement and optimization of medical imaging. Therefore, research on the accuracy of medical imaging draws on techniques from a wide range of disciplines in an attempt to minimize diagnostic errors and improve the healthcare system. This short review of the psychophysical studies in the radiological domain focuses on the recent work conducted in the visual perception of nuclear medicine images and volumetric data.

The Impact That SPECT Collection Angle and Collection Orbit Gives to an Image: Myocardial Digital Phantom Study

We evaluated the effect that collection angle and collection orbit condition gave to an image quantitatively by simulating the single photon emission computed tomography (SPECT) system. Using the Software Package of the Nuclear Medicine Data Processor for Research, we performed making of the myocardial digital phantom, three ways of different simulation of the collection angle and collection orbit, and making of reference of the uniform picture element level. We calculated NMSE for uniformity evaluation and calculated myocardial thickness full width at half maximum (FWHM) for a spatial resolution evaluation. 360 degrees circular orbit collection had best uniformity. 180 degrees noncircular orbit collection had best spatial resolution. By using the digital phantom, we focused on only collection angle and collection orbit condition, and focused on two indexes of the uniformity and the spatial resolution and were able to show a quantitative index.

A novel description of FDG excretion in the renal system: application to metformin-treated models

This paper introduces a novel compartmental model describing the excretion of 18F-fluoro-deoxyglucose (FDG) in the renal system and a numerical method based on the maximum likelihood for its reduction. This approach accounts for variations in FDG concentration due to water re-absorption in renal tubules and the increase of the bladder’s volume during the FDG excretion process. From the computational viewpoint, the reconstruction of the tracer kinetic parameters is obtained by solving the maximum likelihood problem iteratively, using a non-stationary, steepest descent approach that explicitly accounts for the Poisson nature of nuclear medicine data. The reliability of the method is validated against two sets of synthetic data realized according to realistic conditions. Finally we applied this model to describe FDG excretion in the case of animal models treated with metformin. In particular we show that our approach allows the quantitative estimation of the reduction of FDG de-phosphorylation induced by metformin.

Rheumatoid arthritis: Nuclear medicine state-of-the-art imaging

Rheumatoid arthritis (RA) is an autoimmune disease, which is associated with systemic and chronic inflammation of the joints, resulting in synovitis and pannus formation. For several decades, the assessment of RA has been limited to conventional radiography, assisting in the diagnosis and monitoring of disease. Nevertheless, conventional radiography has poor sensitivity in the detection of the inflammatory process that happens in the initial stages of RA. In the past years, new drugs that significantly decrease the progression of RA have allowed a more efficient treatment. Nuclear Medicine provides functional assessment of physiological processes and therefore has significant potential for timely diagnosis and adequate follow-up of RA. Several single photon emission computed tomography (SPECT) and positron emission tomography (PET) radiopharmaceuticals have been developed and applied in this field. The use of hybrid imaging, which permits computed tomography (CT) and nuclear medicine data to be acquired and fused, has increased even more the diagnostic accuracy of Nuclear Medicine by providing anatomical localization in SPECT/CT and PET/CT studies. More recently, fusion of PET with magnetic resonance imaging (PET/MRI) was introduced in some centers and demonstrated great potential. In this article, we will review studies that have been published using Nuclear Medicine for RA and examine key topics in the area.

Modeling Breath-Enhanced Jet Nebulizers to Estimate Pulmonary Drug Deposition

Predictable delivery of aerosol medication for a given patient and drug-device combination is crucial, both for therapeutic effect and to avoid toxicity. The gold standard for measuring pulmonary drug deposition (PDD) is gamma scintigraphy. However, these techniques expose patients to radiation, are complicated, and are relevant for only one patient and drug-device combination, making them less available. Alternatively, in vitro experiments have been used as a surrogate to estimate in vivo performance, but this is time-consuming and has few "in vitro to in vivo" correlations for therapeutics delivered by inhalation. An alternative method for determining inhaled mass and PDD is proposed by deriving and validating a mathematical model, for the individual breathing patterns of normal subjects and drug-device operating parameters. This model was evaluated for patients with cystic fibrosis (CF). This study is comprised of three stages: mathematical model derivation, in vitro testing, and in vivo validation. The model was derived from an idealized patient's respiration cycle and the steady-state operating characteristics of a drug-device combination. The model was tested under in vitro dynamic conditions that varied tidal volume, inspiration-to-expiration time, and breaths per minute. This approach was then extended to incorporate additional physiological parameters (dead space, aerodynamic particle size distribution) and validated against in vivo nuclear medicine data in predicting PDD in both normal subjects and those with CF. The model shows strong agreement with in vitro testing. In vivo testing with normal subjects yielded good agreement, but less agreement for patients with chronic obstructive lung disease and bronchiectasis from CF. The mathematical model was successful in accommodating a wide range of breathing patterns and drug-device combinations. Furthermore, the model has demonstrated its effectiveness in predicting the amount of aerosol delivered to "normal" subjects. However, challenges remain in predicting deposition in obstructive lung disease.

Estimate of FDG Excretion by means of Compartmental Analysis and Ant Colony Optimization of Nuclear Medicine Data

[18F]fluoro-2-deoxy-D-glucose (FDG) is one of the most utilized tracers for positron emission tomography (PET) applications in oncology. FDG-PET relies on higher glycolytic activity in tumors compared to normal structures as the basis of image contrast. As a glucose analog, FDG is transported into malignant cells which typically exhibit an increased radioactivity. However, different from glucose, FDG is not reabsorbed by the renal system and is excreted to the bladder. The present paper describes a novel computational method for the quantitative assessment of this excretion process. The method is based on a compartmental analysis of FDG-PET data in which the excretion process is explicitly accounted for by the bladder compartment and on the application of an ant colony optimization (ACO) algorithm for the determination of the tracer coefficients describing the FDG transport effectiveness. The validation of this approach is performed by means of both synthetic data and real measurements acquired by a PET device for small animals (micro-PET). Possible oncological applications of the results are discussed in the final section.

Tracking patient radiation exposure: Challenges to integrating nuclear medicine with other modalities

AbstractThe cumulative radiation exposure to the patient from multiple radiological procedures can place some individuals at significantly increased risk for stochastic effects and tissue reactions. Approaches, such as those in the International Atomic Energy Agency’s Smart Card program, have been developed to track cumulative radiation exposures to individuals. These strategies often rely on the availability of structured dose reports, typically found in the DICOM header. Dosimetry information is currently readily available for many individual x-ray-based procedures. Nuclear medicine, of which nuclear cardiology constitutes the majority of the radiation burden in the US, currently lags behind x-ray-based procedures with respect to reporting of radiation dosimetric information. This article discusses qualitative differences between nuclear medicine and x-ray-based procedures, including differences in the radiation source and measurement of its strength, the impact of biokinetics on dosimetry, and the capability of current scanners to record dosimetry information. These differences create challenges in applying, monitoring, and reporting strategies used in x-ray-based procedures to nuclear medicine, and integrating dosimetry information across modalities. A concerted effort by the medical imaging community, dosimetry specialists, and manufacturers of imaging equipment is required to develop strategies to improve the reporting of radiation dosimetry data in nuclear medicine. Some ideas on how to address this issue are suggested.