Localization of neurovascular bundles on pelvic CT and evaluation of radiation dose to structures putatively involved in erectile dysfunction after prostate brachytherapy

PURPOSE: To (a) locate neurovascular bundles (NVB) on pelvic CT and (b) retrospectively evaluate relationships between radiation dose to structures putatively involved in prostate brachytherapy-induced erectile dysfunction (ED) and incidence of postbrachytherapy ED. METHODS AND MATERIALS: (a) Right/left NVB were identified on nine prostate MRIs. Structures visible on MRI and CT were cross-referenced. Cross-sectional area of each NVB was measured. (b) All patients treated with implant alone and whose treatment was planned on Variseed (Varian Medical Systems, Palo Alto, CA), with follow-up of >12 months were included; n = 41. Median follow-up was 20 months. All patients were potent (+/- sildenafil) before implant (erection sufficient for intercourse). The right/left NVB (using results from part "a"), penile bulb, and right/left crus were outlined on postimplant CT. Volumes and doses to these structures were calculated. RESULTS: (a) On prostate MRI, NVB was consistently located where the prostate border bends away from the levator ani, at the gland's smallest radius of curvature. Average area of the circle best encompassing the NVB = 0.27 cm(2); diameter was 0.58 cm. (b) 11 of 41 (27%) patients had ED; 30 of 41 were potent (15 with sildenafil). There was no significant difference between potent/impotent patients in isotope, age, diabetes, hypertension, follow-up, or volume of prostate, bulb, right/left NVB, or right/left crus. There was a relationship between smoking and ED (p = 0.05). There was a relationship between bulb %D90 and ED: >10% 67% (4 of 6) vs. <10% 20% (7 of 35) (p = 0.03), which remained when controlling for smoking. There was no relationship between dose to left NVB and potency. There was paradoxical decreased risk of ED with right NVB %V100 >60% (p = 0.019), and right NVB %D60 >100% (p = 0.003). There was no relationship between dose to right/left crus and ED. CONCLUSIONS: A reliable method for localizing NVB on CT is demonstrated. There is no increased risk of prostate brachytherapy-induced ED with increasing dose to crus or NVB at the doses given in this study. There is a possible dose-response relationship between dose to the bulb and risk of ED.     

The challenges and pitfalls of incorporating evidence from cardiovascular outcomes trials in health economic modelling of type 2 diabetes

The clinical evidence base for evaluating modern type 2 diabetes interventions has expanded greatly in recent years, with numerous efficacious treatment options available (including dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter-2 inhibitors). The cardiovascular safety of these interventions has been assessed individually versus placebo in numerous cardiovascular outcomes trials (CVOTs), statistically powered to detect differences in a composite endpoint of major adverse cardiovascular events. There have been growing calls to incorporate these data in the long-term modelling of type 2 diabetes interventions because current diabetes models were developed prior to the conduct of the CVOTs and therefore rely on risk equations developed in the absence of these data. However, there are numerous challenges and pitfalls to avoid when using data from CVOTs. The primary concerns are around the heterogeneity of the trials, which have different study durations, inclusion criteria, rescue medication protocols and endpoint definitions; this results in significant uncertainty when comparing two or more interventions evaluated in separate CVOTs, as robust adjustment for these differences is difficult. Analyses using CVOT data inappropriately can dilute clear evidence from head-to-head clinical trials, and blur healthcare decision making. Calibration of existing models may represent an approach to incorporating CVOT data into diabetes modelling, but this can only offer a valid comparison of one intervention versus placebo based on a single CVOT. Ideally, model development should utilize patient-level data from CVOTs to prepare novel risk equations that can better model modern therapies for type 2 diabetes.     

Acute cholecystitis: diagnostic accuracy of percutaneous aspiration of the gallbladder

Results of gallbladder bile aspiration and culture were correlated with presence or absence of acute cholecystitis in 36 patients to test the role of these procedures in hospitalized patients with sepsis. Diagnostic aspiration of the gallbladder was performed in 11 patients, and in the remaining patients a combination of percutaneous aspiration, percutaneous cholecystostomy, or cholecystectomy was used. Bile culture was not helpful in the prediction of acute cholecystitis, since results were not available for a minimum of 24-48 hours after aspiration. In addition, gram-stained smears and bile cultures suffered from low sensitivity (48% and 38%, respectively); consequently, a negative test does not allow the diagnosis of acute cholecystitis to be excluded. Bile aspiration of the gallbladder thus has a limited role in the diagnosis of this condition.     

MR imaging of the scrotum with a high-resolution surface coil

Magnetic resonance (MR) imaging of the scrotum with a high-resolution surface coil was performed in ten healthy volunteers and 20 patients with scrotal abnormalities demonstrated by high-resolution real-time ultrasound (US). Four patients had an abnormal testis (two tumors, one cyst, one testicular atrophy), and 16 patients had extratesticular abnormalities (four hydroceles, five epididymal cysts, one hernia, and six cases of epididymitis). The normal structures of the scrotum were depicted clearly on MR images. In all cases, the tunica albuginea was easily differentiated from the testis and epididymis. MR imaging enabled one to distinguish intratesticular from extratesticular lesions and to determine whether a lesion was solid or cystic. Complicated and simple fluid collections could also be differentiated. In general, MR imaging and US scanning provided similar information. A potential advantage of MR imaging is in the evaluation of patients with painful scrotal lesions that may limit US evaluation.     

Percutaneous vascular intervention after surgical shunting for portal hypertension

Twenty percutaneous transluminal angioplasty (PTA) procedures and 13 percutaneous venous embolization (PVE) procedures were performed in 23 patients who either had or were at risk for the development of recurrent bleeding, hepatic encephalopathy, or both after surgical shunt placement for portal hypertension. PTA, performed in 12 patients with significant shunt stenoses, resulted in reduction or elimination of gradients in all patients; rebleeding has occurred in only one patient. Complications consisted of one fatal rupture of a mesocaval interposition vein graft and one balloon rupture requiring surgical removal. PVE, performed in 11 patients, resulted in measurable improvement in four of seven encephalopathic patients and temporary control in the two patients with intractable bleeding. Three patients underwent PVE prophylactically. PTA of graft strictures is a valuable treatment modality. Embolization may be helpful in selected cases of hepatic encephalopathy.