According to the PI-RADS v2.1 sector mapping, the prostate (excluding seminal vesicles and the external urethral sphincter) has been divided into how many sectors?

Correct Answer: B

Rationale: PI-RADS v2.1 divides prostate into 38 sectors 36 prostate zones (base, mid, apex; anterior/posterior) plus 2 urethra standardized for MRI reporting. 27 is outdated (v1) too few. 41/43 include seminal vesicles/sphincter excluded here. 38 distinguishes it, critical for precise cancer localization, unlike old or inclusive counts.

Correct Answer: A

Rationale: Acute tubular necrosis (ATN) is the top cause of acute renal failure ischemia/toxins (e.g., sepsis) damage tubules, impairing filtration. Glomerulonephritis (immune) is less frequent chronic more common. Vasculitis (e.g., ANCA) is rare systemic. Tubulointerstitial nephritis (drugs) occurs but trails ATN less acute. ATN's prevalence distinguishes it, critical for ARF etiology, unlike glomerular or interstitial causes.

Correct Answer: C

Rationale: Plasma aldosterone-to-renin ratio (ARR) screens primary aldosteronism best high aldosterone, low renin (e.g., adenoma) flags it reliably. Serum potassium (hypokalemia) is suggestive non-specific. Urine aldosterone is diagnostic, not screening cumbersome. Adrenal vein sampling confirms laterality post-screening. ARR's sensitivity distinguishes it, critical for early detection, unlike secondary or invasive tests.

Correct Answer: D

Rationale: Sickle cell disease tops pediatric priapism sickling blocks penile outflow (ischemic), prevalent in affected populations. Idiopathic is less defined residual category. Trauma causes high-flow rarer. Leukemia clogs vessels significant but less common. Sickle cell's dominance distinguishes it, key to pediatric etiology, unlike trauma or hematologic alternatives.

Correct Answer: C

Rationale: Alpha1c isn't a recognized receptor misnomer; Alpha1a, Alpha1b, and Alpha1d mediate LUTS (e.g., BPH). Alpha1a dominates prostate/bladder neck obstruction. Alpha1d affects detrusor irritative. Alpha1b is vascular less LUTS-specific. Non-existent Alpha1c distinguishes it, key to receptor pharmacology, unlike active mediators.