**Question:** In Renal cell carcinoma investigation of choice to evaluate inferior vena cava and renal vein for thrombus –

A. Ultrasonography
B. Computed tomography (CT) angiography
C. Magnetic resonance imaging (MRI)
D. Angiography

**Correct Answer:** B. Computed tomography (CT) angiography

**Core Concept:**
In the context of Renal cell carcinoma, imaging investigations are essential to detect possible venous thrombus extension, particularly in the inferior vena cava (IVC) and renal veins. These investigations help guide management decisions, prognosis, and treatment strategies.

**Why the Correct Answer is Right:**
Computed tomography angiography (CTA) is the correct choice for evaluating the IVC and renal veins due to its superior sensitivity and specificity compared to other modalities. The CT scan combines a detailed anatomical assessment of the renal veins and IVC with the ability to visualize the vascular system, allowing for accurate detection of thrombus extension.

**Why Each Wrong Option is Incorrect:**

A. Ultrasonography (USG) is a less sensitive and specific imaging modality for detecting renal vein and IVC thrombus, particularly in cases of deep thrombus extension.

C. Magnetic resonance imaging (MRI) is not the preferred modality for renal vein and IVC thrombus evaluation. It lacks the ability to visualize the vascular system and may not provide sufficient information about venous thrombus extension.

D. Angiography is an invasive procedure involving contrast injection, which is not suitable for routine evaluation of renal vein and IVC thrombus due to its invasiveness, ionizing radiation exposure, and risk of complications.

**Clinical Pearl:**
In cases of suspected renal cell carcinoma with possible venous thrombus extension, CTA is the preferred imaging modality due to its high sensitivity and specificity. This enables accurate diagnosis and guides management decisions, improving patient outcomes.