Kidney efficiency index quantitative parameter of a dynamic renal scintigraphy. II. usefulness in the diagnosis of obstructive nephropathy

BACKGROUND: One of the main indications for DRS is a diagnosis of obstructive uro-/nephropathy. In standard practice,this study includes the assessment of sequential scintigraphic images, renographic curves and such quantitative parametersas TMAX, T1/2 and split function of each kidney (SF). Due to the relative nature of SF and limitations of diagnostic capabilities ofTMAX and T1/2, DRS was expanded to include new quantitative parameters describing kidney function in absolute values. Thisstudy aims to evaluate the usefulness of kidney efficiency index (KEi) — new, in-house developed parameter proportional tothe average clearance function of the kidney.MATERIAL AND METHODS: The study included 156 people aged 18–84 (average 51) years. The first group, from whichnormative values of new parameters were determined, consisted of 20 healthy volunteers. The second group consisted of 136patients selected retrospectively, based on archived scintigraphic data. “Normalcy rate” (percentage of normal results amongselected 62 patients with a low likelihood of obstructive uro-/nephropathy) was used to evaluate the reliability of KEi. A comparativedifferential analysis of obstructive uro-/nephropathy, based on standard and new DRS parameters, was performedon selected 74 patients (92 kidneys) with single functioning kidney or bilateral obstructive uropathy, where SF is unreliable.RESULTS: Normative values: KEi ≥ 8; Normalcy rate for KEi: 95%. In comparison with standard DRS evaluation, application of KEichanged the diagnosis in 1/3 of assessed kidneys (from uropathy to nephropathy in 27/92 kidneys and vice versa in 4 kidneys).CONCLUSIONS: KEi enables reproducible, quantitative assessment of absolute kidney function without any modificationsof the standard DRS protocol. Its values can be compared between independent studies (e.g. follow-up examinations). KEicorrected the diagnosis of obstructive uro-/nephropathy in cases of single functioning kidney or bilateral obstructive uropathy

Generalized Rotne–Prager–Yamakawa approximation for Brownian dynamics in shear flow in bounded, unbounded, and periodic domains

Inclusion of hydrodynamic interactions is essential for a quantitatively accurate Brownian dynamics simulation of colloidal suspensions or polymer solutions. We use the generalized Rotne–Prager–Yamakawa (GRPY) approximation, which takes into account all long-ranged terms in the hydrodynamic interactions, to derive the complete set of hydrodynamic matrices in different geometries: unbounded space, periodic boundary conditions of Lees–Edwards type, and vicinity of a free surface. The construction is carried out both for non-overlapping as well as for overlapping particles. We include the dipolar degrees of freedom, which allows one to use this formalism to simulate the dynamics of suspensions in a shear flow and to study the evolution of their rheological properties. Finally, we provide an open-source numerical package, which implements the GRPY algorithm in Lees–Edwards periodic boundary conditions

Kidney Efficiency Index — quantitative parameter of a dynamic renal scintigraphy. I. Theory and preliminary verification

BACKGROUND: One of the basic clinical indications for dynamic renal scintigraphy (DRS) is a diagnosis of obstructiveuropathy and/or nephropathy. Currently, a basic quantitative criterion for diagnosing nephropathy is the percentage of individualkidney’s contribution in the global uptake of a radiopharmaceutical from the blood (so-called Split Function - SF).From a clinical point of view, a parameter evaluating a radiopharmaceutical uptake and reflecting the efficiency of a specifickidney, determined independently of the total uptake of both kidneys, would be much more useful. Based on a Rutland theory,a kidney uptake constant K proportional to a radiotracer uptake by individual kidney was introduced and applied to DRS with99mTc-ethylene-1-dicysteine (99mTc-EC). In addition, a kidney efficiency index (KEi) was also worked out as a new parameterobtained by dividing the uptake constant K by the surface of the ROI of a given kidney, which can be interpreted as the average“efficiency” of clearance of a kidney.MATERIAL AND METHODS: K and KEi values were verified in 72 studies selected retrospectively from patients referredroutinely for DRS, with available current level of blood creatinine, used for calculation of estimated GFR (eGFR) according toa CKD-EPI formula. After splitting of eGFR values into individual kidneys according to SF, single kidney eGFR values (SKeGFR)were obtained and then used as a verification method for SF, K and KEi values.RESULTS: Correlation between SF and SKeGFR values, rsp = 0.64, was significantly weaker (p < 0.0022) than the correlationof SKeGFR values with K uptake constants and KEi indices: 0.90 and 0.84, respectively.CONCLUSIONS: Uptake constant K and KEi, as quantitative parameters, give the opportunity to analyze a function of eachkidney separately and in an absolute way. KEi also allows for a reliable assessment of kidneys of atypical sizes (larger or smallerthan average). It also gives the opportunity to create normative values for this parameter and may be useful in a number ofclinical situations where the diagnostic effectiveness of such a relative parameter as SF, is severely limited, e.g. in assessinga large kidney with hydronephrosis or while differing a cirrhotic from hypoplastic (i.e. a small but properly functioning) kidney

Higher processing repeatability of myocardial flow reserve calculated using net retention model compared to one compartment model in SPECT studies

Abstract Dynamic assessment of myocardial blood flow (MBF) and myocardial flow reserve (MFR) provides additional information that can improve diagnostic accuracy of radionuclide myocardial perfusion imaging in some clinical situations. This study assessed processing repeatability of these parameters calculated using two models—net retention (RET) and one compartment (1CM) in dynamic SPECT studies, using the latest version of Corridor 4DM software (v2024). Data of 107 patients were analyzed retrospectively (57 of whom were assessed in our previous study using 4DM v2015). Dynamic SPECT studies were carried out using a routine two-day rest-dipyridamole protocol. Data was processed in 4DM v2024 twice by one operator and once by another operator. Automatic heart image positioning during post-processing in 4DM v2024 was significantly improved compared to v2015, reducing the number of studies requiring extensive manual corrections from 41 to 12%. This significantly improved interobserver processing repeatability of MFR values in RCA territory compared to our previous study using v2015—from r = 0.67 to 0.85 (p = 0.0034). Interobserver processing repeatability of MBF and MFR in all 107 patients was significantly better in RET model compared to 1CM model. In conclusion, RET model is more reliable for calculating MBF and MFR values based on dynamic SPECT studies