ABSTRACT
PURPOSE: To compare spatial distributions of radiopaque glass (RG) microspheres, trisacryl gelatin (TAG) microspheres, and polyvinyl alcohol (PVA) foam particles within a planar in vitro microvascular model of the hyperplastic hemiprostate. MATERIALS AND METHODS: A microvascular model simulating hyperplastic hemiprostate was perfused with a water-glycerin mixture. A microcatheter was positioned distal to the model's prostatic artery origin and embolic particles (RG: 50 µm, 100 µm, and 150 µm; TAG: 100-300 µm and 300-500 µm; and PVA: 90-180 µm and 180-300 µm) were administered using a syringe pump. Microscopic imaging and subsequent semantic segmentation were performed to quantify particle distributions within the models. Distal penetrations were quantified statistically via modal analysis of the particle distributions. RESULTS: Maximum distal penetration was observed for RG 50, followed by RG 100 and then TAG 100-300 and RG 150. TAG 300-500, PVA 90-180, and PVA 180-300 particles exhibited the lowest distal penetrations. The distal penetration metrics between groups were significantly different (p < 0.05) except between TAG 100-300 and RG 150 and between PVA 90-180 and PVA 180-300. CONCLUSIONS: Comparing the spatial distributions of embolic particles in an in vitro microvascular model simulating the hyperplastic hemiprostate revealed that noncompressible particles and those with narrower size calibrations and smaller relative diameters exhibited higher degrees of distal packing. The embolization front was less distinct for particles with wider size calibrations, which resulted in smaller, more distal emboli along with larger, more proximal emboli. PVA and TAG 300-500 particles both exhibited relatively low overall distal penetration.
ABSTRACT
Summary: Hypercalcaemia is a common complication seen in malignancy, frequently due to paraneoplastic parathyroid hormone-related peptide production or osteolytic bony metastases. We present a 58-year-old female with immunotherapy-mediated hypophysitis causing secondary cortisol deficiency resulting in severe glucocorticoid-responsive hypercalcaemia. Whilst hypophysitis is a well recognised adverse event in those receiving immunotherapy for advanced malignancy, it does not typically present with hypercalcaemia. The mechanism responsible for hypercalcaemia due to hypocortisolaemia has not been fully elucidated although hypotheses include the effects of volume depletion and thyroxine's action on bone. Prompt treatment with glucocorticoids caused an improvement in the patient's symptoms and corrected her hypercalcaemia which later returned after an attempted glucocorticoid wean. With the increasing uptake of immunotherapy, clinicians should be aware of this unusual presentation of immunotherapy-related hypophysitis and secondary hypocortisolaemia which can be life-threatening if the diagnosis is delayed. Learning points: Immunotherapy can cause inflammation of the pituitary gland resulting in secondary hypocortisolaemia, which can, though rarely, present as hypercalcaemia. Secondary hypocortisolaemia requires prompt recognition and treatment with glucocorticoids. Glucocorticoid replacement leads to rapid clinical and biochemical improvement in these patients. The differential diagnosis for glucocorticoid-responsive hypercalcaemia extends beyond granulomatous disorders (e.g. sarcoidosis, tuberculosis) to adrenocorticotrophic hormone and cortisol deficiency, particularly in patients receiving immunotherapy. Hypocortisolaemia can lead to hypercalcaemia through various proposed mechanisms. Low serum glucocorticoids are associated with reduced blood volume, thus reducing renal calcium excretion. In addition, without glucocorticoid's inhibitory action, thyroxine appears to drive calcium mobilisation from bone.
ABSTRACT
PURPOSE: To utilize an in vitro microvascular hepatic tumor model to compare the deposition characteristics of glass yttrium-90 microspheres using the dual-syringe (DS) and traditional bolus administration methods. MATERIALS AND METHODS: The microvascular tumor model represented a 3.5-cm tumor in a 1,400-cm3 liver with a total hepatic flow of 160 mL/min and was dynamically perfused. A microcatheter was placed in a 2-mm artery feeding the tumor model and 2 additional nontarget arteries. Glass microspheres with a diameter of 20-30 µm were administered using 2 methods: (a) DS delivery at a concentration of 50 mg/mL in either a single, continuous 2-mL infusion or two 1-mL infusions and (b) bolus delivery (BD) of 100 mg of microspheres in a single 3-mL infusion. RESULTS: Overall, the degree of on-target deposition of the microspheres was 85% ± 11%, with no significant differences between the administration methods. Although the distal penetration into the tumor arterioles was approximately 15 mm (from the second microvascular bifurcation of the tumor model) for all the cases, the distal peak particle counts were significantly higher for the DS delivery case (approximately 5 × 105 microspheres achieving distal deposition vs 2 × 105 for the BD case). This resulted in significantly higher deposition uniformity within the tumor model (90% for the DS delivery case vs 80% for the BD case, α = 0.05). CONCLUSIONS: The use of this new in vitro microvascular hepatic tumor model demonstrated that the administration method can affect the deposition of yttrium-90 microspheres within a tumor, with greater distal deposition and more uniform tumor coverage when the microspheres are delivered at consistent concentrations using a DS delivery device. The BD administration method was associated with less favorable deposition characteristics of the microspheres.
