Liver abscess
- US = first‑line (hypoechoic, internal echoes, posterior enhancement, irregular wall; follow liquefaction and guide drainage). Multiphasic CECT = best characterisation.
- CT signs: double target sign (central low density + enhancing inner wall + low‑density outer oedema ring), cluster sign (small pyogenic abscesses coalescing into a larger cavity), gas (Klebsiella, E. coli), right pleural effusion.