Can cortical atrophy be visualized on a CT scan in a patient with severe bilateral cortical atrophy and impaired renal function?

Can Cortical Atrophy Be Visualized on CT Scan?

Yes, cortical atrophy can be definitively visualized on CT scan, including in patients with severe bilateral cortical atrophy and impaired renal function. 1

CT Capabilities for Detecting Cortical Atrophy

CT without contrast is sufficient to demonstrate cortical atrophy and should be used when renal impairment is present. 1 The Canadian Consensus Conference on Dementia explicitly recommends non-contrast CT with coronal reformations to better assess atrophy patterns. 1

Specific CT Findings of Cortical Atrophy

CT can demonstrate multiple features of cortical atrophy: 1

• Cortical thinning - direct visualization of reduced cortical thickness
• Renal scarring - chronic changes from prior injury
• Calyceal clubbing or dilatation - secondary structural changes
• Renal asymmetry - differential involvement between kidneys

Recommended Imaging Protocol

When CT is performed for evaluating atrophy, the following approach is recommended: 1

• Non-contrast CT is the appropriate modality when renal function is impaired
• Coronal reformations should be obtained to optimize assessment of atrophy patterns
• Semi-quantitative scales should be applied, including the global cortical atrophy (GCA) scale and medial temporal lobe atrophy (MTA) scale for systematic interpretation

Critical Considerations in Renal Impairment

In patients with impaired renal function, contrast-enhanced CT should be avoided to prevent contrast-induced nephropathy. 1, 2 The ACR guidelines specifically note that for patients with GFR <30 mL/min/1.73m², contrast-enhanced CT should be avoided if possible, and for GFR 30-45 mL/min/1.73m², non-contrast alternatives should be considered first. 2

Alternative Imaging When Contrast Is Needed

If functional or vascular assessment is required beyond structural evaluation: 1, 3

• MRI without contrast can provide superior soft tissue characterization without nephrotoxic risk
• MRI with gadolinium should only be used if GFR is adequate, as gadolinium carries risk of nephrogenic systemic fibrosis in severe renal impairment

Clinical Context: Bilateral Cortical Atrophy

Research confirms that bilateral renal cortical atrophy is readily identifiable on CT imaging: 4, 5

• Contrast-enhanced CT shows characteristic low attenuation of cortex in acute cortical necrosis, though this requires contrast administration
• Non-contrast CT can still demonstrate chronic cortical atrophy through direct visualization of cortical thinning and structural changes
• Bilateral cortical atrophy has been documented on CT in patients with chronic conditions including emphysematous cystitis and chronic renal failure 5, 6

Practical Algorithm

For a patient with suspected bilateral cortical atrophy and impaired renal function: 1

1. Order non-contrast CT with coronal reformations
2. Apply semi-quantitative atrophy scales (GCA scale) during interpretation
3. Avoid iodinated contrast given renal impairment
4. Consider MRI without contrast if additional soft tissue characterization is needed beyond what CT provides