Interrater Agreement of Bosniak Classification Version 2019 and Version 2005 for Cystic Renal Masses at CT and MRI.

Background The Bosniak classification system for cystic renal masses was updated in 2019 in part to improve agreement compared with the 2005 version. Purpose To compare and investigate interrater agreement of Bosniak version 2019 and Bosniak version 2005 at CT and MRI. Materials and Methods In this retrospective single-center study, a blinded eight-reader assessment was performed in which 195 renal masses prospectively considered Bosniak IIF-IV (95 at CT, 100 at MRI, from 2006 to 2019 with version 2005) were re-evaluated with Bosniak versions 2019 and 2005. Radiologists (four faculty members, four residents) who were blinded to the initial clinical reading and histopathologic findings assessed all feature components and reported the overall Bosniak class for each system independently. Agreement was assessed with Gwet agreement coefficients. Uni- and multivariable linear regression models were developed to identify predictors of dispersion in the final Bosniak class assignment that could inform system refinement. Results A total of 185 patients were included (mean age, 63 years ± 13 [standard deviation]; 118 men). Overall interrater agreement was similar between Bosniak version 2019 and version 2005 (Gwet agreement coefficient: 0.51 [95% CI: 0.45, 0.57] vs 0.46 [95% CI: 0.42, 0.51]). This was true for experts (0.54 vs 0.49) and novices (0.50 vs 0.47) and at CT (0.56 vs 0.51) and MRI (0.52 vs 0.43). Nine percent of masses prospectively considered cystic using Bosniak version 2005 criteria were considered solid using version 2019 criteria. In general, masses were more commonly classified in lower categories when radiologists used Bosniak version 2019 criteria compared with version 2005 criteria. The sole predictor of dispersion in Bosniak version 2019 class assignment was dispersion in septa or wall quality (ie, smooth vs irregular thickening vs nodule; 72% [MRI] and 60% [CT] overall model variance explained; multivariable P < .001). Conclusion Overall interrater agreement was similar between Bosniak version 2019 and version 2005; disagreements in septa or wall quality were common and strongly predictive of variation in Bosniak class assignment. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Eberhardt in this issue.

The angiotensin receptor blocker losartan reduces coronary arteriole remodeling in type 2 diabetic mice.

Cardiovascular complications are a leading cause of morbidity and mortality in type 2 diabetes mellitus (T2DM) and are associated with alterations of blood vessel structure and function. Although endothelial dysfunction and aortic stiffness have been documented, little is known about the effects of T2DM on coronary microvascular structural remodeling. The renin-angiotensin-aldosterone system plays an important role in large artery stiffness and mesenteric vessel remodeling in hypertension and T2DM. The goal of this study was to determine whether the blockade of AT1R signaling dictates vascular smooth muscle growth that partially underlies coronary arteriole remodeling in T2DM. Control and db/db mice were given AT1R blocker losartan via drinking water for 4 weeks. Using pressure myography, we found that coronary arterioles from 16-week db/db mice undergo inward hypertrophic remodeling due to increased wall thickness and wall-to-lumen ratio with a decreased lumen diameter. This remodeling was accompanied by decreased elastic modulus (decreased stiffness). Losartan treatment decreased wall thickness, wall-to-lumen ratio, and coronary arteriole cell number in db/db mice. Losartan treatment did not affect incremental elastic modulus. However, losartan improved coronary flow reserve. Our data suggest that Ang II-AT1R signaling mediates, at least in part, coronary arteriole inward hypertrophic remodeling in T2DM without affecting vascular mechanics, further suggesting that targeting the coronary microvasculature in T2DM may help reduce cardiac ischemic events.

In vivo and in vitro cardiac responses to beta-adrenergic stimulation in volume-overload heart failure.

Hearts in volume overload (VO) undergo progressive ventricular hypertrophy resulting in chronic heart failure that is unresponsive to ß-adrenergic agonists. This study compared left ventricular (LV) and isolated cardiomyocyte contractility and ß-adrenergic responsiveness in rats with end-stage VO heart failure (HF). Adult male Sprague-Dawley rats were studied 21 weeks after aortocaval fistula (ACF) or sham surgery. Echocardiography revealed decreased fractional shortening accompanied by increased LV chamber diameter and decreased eccentric dilatation index at end-stage ACF compared to sham. Hemodynamic measurements showed a decrease in the slope of end-systolic pressure-volume relationship, indicating systolic dysfunction. Isolated LV myocytes from ACF exhibited decreased peak sarcomere shortening and kinetics. Both Ca2+ transient amplitude and kinetics were increased in ACF myocytes, with no change under the integrated Ca2+ curves relating to contraction and relaxation phases. Increases in ryanodine receptor and phospholamban phosphorylation, along with a decrease in SERCA2 levels, were observed in ACF. These changes were associated with decreased expression of ß-myosin heavy chain, cardiac troponin I and cardiac myosin binding protein-C. In vivo inotropic responses to ß-adrenergic stimulation were attenuated in ACF. Interestingly, ACF myocytes exhibited a similar peak shortening to those of sham in response to a ß-adrenergic agonist. The protein expression of the gap junction protein connexin-43 was decreased, although its phosphorylation at Ser-368 increased. These changes were associated with alterations in Src and ZO-1. In summary, these data suggest that the disconnect in ß-adrenergic responsiveness between in vivo and in vitro conditions may be associated with altered myofilament Ca2+ sensitivity and connexin-43 degradation.

Collagen XIV is important for growth and structural integrity of the myocardium.

Collagen XIV is a fibril-associated collagen with an interrupted triple helix (FACIT). Previous studies have shown that this collagen type regulates early stages of fibrillogenesis in connective tissues of high mechanical demand. Mice null for Collagen XIV are viable, however formation of the interstitial collagen network is defective in tendons and skin leading to reduced biomechanical function. The assembly of a tightly regulated collagen network is also required in the heart, not only for structural support but also for controlling cellular processes. Collagen XIV is highly expressed in the embryonic heart, notably within the cardiac interstitium of the developing myocardium, however its role has not been elucidated. To test this, we examined cardiac phenotypes in embryonic and adult mice devoid of Collagen XIV. From as early as E11.5, Col14a1(-/-) mice exhibit significant perturbations in mRNA levels of many other collagen types and remodeling enzymes (MMPs, TIMPs) within the ventricular myocardium. By post natal stages, collagen fibril organization is in disarray and the adult heart displays defects in ventricular morphogenesis. In addition to the extracellular matrix, Col14a1(-/-) mice exhibit increased cardiomyocyte proliferation at post natal, but not E11.5 stages, leading to increased cell number, yet cell size is decreased by 3 months of age. In contrast to myocytes, the number of cardiac fibroblasts is reduced after birth associated with increased apoptosis. As a result of these molecular and cellular changes during embryonic development and post natal maturation, cardiac function is diminished in Col14a1(-/-) mice from 3 months of age; associated with dilation in the absence of hypertrophy, and reduced ejection fraction. Further, Col14a1 deficiency leads to a greater increase in left ventricular wall thickening in response to pathological pressure overload compared to wild type animals. Collectively, these studies identify a new role for type XIV collagen in the formation of the cardiac interstitium during embryonic development, and highlight the importance of the collagen network for myocardial cell survival, and function of the working myocardium after birth.

Dynamic micro- and macrovascular remodeling in coronary circulation of obese Ossabaw pigs with metabolic syndrome.

Previous studies from our laboratory showed that coronary arterioles from type 2 diabetic mice undergo inward hypertrophic remodeling and reduced stiffness. The aim of the current study was to determine if coronary resistance microvessels (CRMs) in Ossabaw swine with metabolic syndrome (MetS) undergo remodeling distinct from coronary conduit arteries. Male Ossabaw swine were fed normal (n = 7, Lean) or hypercaloric high-fat (n = 7, MetS) diets for 6 mo, and then CRMs were isolated and mounted on a pressure myograph. CRMs isolated from MetS swine exhibited decreased luminal diameters (126 ± 5 and 105 ± 9 µm in Lean and MetS, respectively, P < 0.05) with thicker walls (18 ± 3 and 31 ± 3 µm in Lean and MetS, respectively, P < 0.05), which doubled the wall-to-lumen ratio (14 ± 2 and 30 ± 2 in Lean and MetS, respectively, P < 0.01). Incremental modulus of elasticity (IME) and beta stiffness index (BSI) were reduced in CRMs isolated from MetS pigs (IME: 3.6 × 10(6) ± 0.7 × 10(6) and 1.1 × 10(6) ± 0.2 × 10(6) dyn/cm(2) in Lean and MetS, respectively, P < 0.001; BSI: 10.3 ± 0.4 and 7.3 ± 1.8 in Lean and MetS, respectively, P < 0.001). BSI in the left anterior descending coronary artery was augmented in pigs with MetS. Structural changes were associated with capillary rarefaction, decreased hyperemic-to-basal coronary flow velocity ratio, and augmented myogenic tone. MetS CRMs showed a reduced collagen-to-elastin ratio, while immunostaining for the receptor for advanced glycation end products was selectively increased in the left anterior descending coronary artery. These data suggest that MetS causes hypertrophic inward remodeling of CRMs and capillary rarefaction, which contribute to decreased coronary flow and myocardial ischemia. Moreover, our data demonstrate novel differential remodeling between coronary micro- and macrovessels in a clinically relevant model of MetS.

Temporal pattern of left ventricular structural and functional remodeling following reversal of volume overload heart failure.

Current surgical management of volume overload-induced heart failure (HF) leads to variable recovery of left ventricular (LV) function despite a return of LV geometry. The mechanisms that prevent restoration of function are unknown but may be related to the timing of intervention and the degree of LV contractile impairment. This study determined whether reduction of aortocaval fistula (ACF)-induced LV volume overload during the compensatory stage of HF results in beneficial LV structural remodeling and restoration of pump function. Rats were subjected to ACF for 4 wk; a subset then received a load-reversal procedure by closing the shunt using a custom-made stent graft approach. Echocardiography or in vivo pressure-volume analysis was used to assess LV morphology and function in sham rats; rats subjected to 4-, 8-, or 15-wk ACF; and rats subjected to 4-wk ACF followed by 4- or 11-wk reversal. Structural and functional changes were correlated to LV collagen content, extracellular matrix (ECM) proteins, and hypertrophic markers. ACF-induced volume overload led to progressive LV chamber dilation and contractile dysfunction. Rats subjected to short-term reversal (4-wk ACF + 4-wk reversal) exhibited improved chamber dimensions (LV diastolic dimension) and LV compliance that were associated with ECM remodeling and normalization of atrial and brain natriuretic peptides. Load-independent parameters indicated LV systolic (preload recruitable stroke work, Ees) and diastolic dysfunction (tau, arterial elastance). These changes were associated with an altered α/ß-myosin heavy chain ratio. However, these changes were normalized to sham levels in long-term reversal rats (4-wk ACF + 11-wk reversal). Acute hemodynamic changes following ACF reversal improve LV geometry, but LV dysfunction persists. Gradual restoration of function was related to normalization of eccentric hypertrophy, LV wall stress, and ECM remodeling. These results suggest that mild to moderate LV systolic dysfunction may be an important indicator of the ability of the myocardium to remodel following the reversal of hemodynamic overload.

Coronary arterioles in type 2 diabetic (db/db) mice undergo a distinct pattern of remodeling associated with decreased vessel stiffness.

Little is known about the impact of type 2 diabetes mellitus (DM) on coronary arteriole remodeling. The aim of this study was to determine the mechanisms that underlie coronary arteriole structural remodeling in type 2 diabetic (db/db) mice. Passive structural properties of septal coronary arterioles isolated from 12- to 16-week-old diabetic db/db and control mice were assessed by pressure myography. Coronary arterioles from 12-week-old db/db mice were structurally similar to age-matched controls. By 16 weeks of age, coronary wall thickness was increased in db/db arterioles (p < 0.01), while luminal diameter was reduced (control: 118 ± 5 µm; db/db: 102 ± 4 µm, p < 0.05), augmenting the wall-to-lumen ratio by 58% (control: 5.9 ± 0.6; db/db: 9.5 ± 0.4, p < 0.001). Inward hypertrophic remodeling was accompanied by a 56% decrease in incremental elastic modulus (p < 0.05, indicating decreased vessel coronary wall stiffness) and a ~30% reduction in coronary flow reserve (CFR) in diabetic mice. Interestingly, aortic pulse wave velocity and femoral artery incremental elastic modulus were increased (p < 0.05) in db/db mice, indicating macrovascular stiffness. Molecular tissue analysis revealed increased elastin-to-collagen ratio in diabetic coronaries when compared to control and a decrease in the same ratio in the diabetic aortas. These data show that coronary arterioles isolated from type 2 diabetic mice undergo inward hypertrophic remodeling associated with decreased stiffness and increased elastin-to-collagen ratio which results in a decreased CFR. This study suggests that coronary microvessels undergo a different pattern of remodeling from macrovessels in type 2 DM.