The 2026 Brand Review flags acronym density as one of the brand's biggest barriers to entry. This glossary is the answer: a single, linkable, plain-English reference for every clinical term we use on this site, written for an interested non-specialist.
A way of dividing the liver into eight functionally independent segments, each with its own blood supply, bile drainage, and lymphatic outflow. Named for the French surgeon Claude Couinaud, who described it in 1957.
Why it matters: surgeons plan resections around Couinaud segments, because removing tissue along these boundaries preserves the function of what remains. Hepatica reports volumetry and tissue quality per Couinaud segment for exactly this reason.
See also: Hepatica
A measurement of how long water molecules in tissue take to relax after a magnetic pulse, corrected for the influence of iron content. The result is a single number, per voxel, that scales with liver inflammation and fibrosis together.
cT1 is the quantitative readout at the heart of LiverMultiScan. It is peer-reviewed across 100+ publications and used as a primary endpoint in MASH and NAFLD trials.
See also: LiverMultiScan · PDFF · MASH
Endoscopic retrograde cholangiopancreatography. An invasive procedure that combines endoscopy with X-ray imaging to visualise the bile ducts and pancreatic duct. Effective but carries non-trivial risk of pancreatitis and bleeding.
Why it matters: MRCP+ exists to replace diagnostic ERCP wherever possible, keeping the diagnostic insight, removing the procedural risk.
See also: MRCP+ · MRCP
Magnetic resonance cholangiopancreatography. A non-invasive MRI sequence that visualises the biliary and pancreatic ducts. Standard of care for most biliary imaging, but historically qualitative, the radiologist describes what they see; nothing is measured.
MRCP+ adds the quantification: dimensions, volumes, and automatically-flagged anomalies.
See also: MRCP+ · ERCP
Metabolic dysfunction-associated steatohepatitis. The current preferred name (since 2023) for what was previously called NASH, fatty liver disease driven by metabolic dysfunction, with inflammation and progressive scarring.
Why it matters: MASH is the most active disease area in liver pharma today, with multiple Phase 2b and Phase 3 programmes using quantitative imaging biomarkers as primary endpoints. Perspectum's cT1 is one of the most-validated of those biomarkers.
See also: NAFLD · NASH · MASLD · LiverMultiScan
Non-alcoholic fatty liver disease. The umbrella term (now being replaced by MASLD) for the spectrum of liver disease driven by fat accumulation in patients who do not drink heavily, from simple steatosis to MASH to cirrhosis.
Why it matters: the leading cause of chronic liver disease globally, affecting an estimated quarter of adults. The clinical question is always: which patients will progress, and how fast?
See also: MASH · MASLD
Non-alcoholic steatohepatitis. The older name for what is now called MASH. Most clinical and regulatory documents from before 2023 still use "NASH", both terms refer to the same disease.
See also: MASH · NAFLD
Proton density fat fraction. A quantitative MRI measurement of the proportion of fat in a tissue, expressed as a percentage. The reference standard for non-invasive liver fat quantification.
PDFF is reported alongside cT1 in LiverMultiScan, and is one of the most regulator-accepted imaging biomarkers in liver disease today.
See also: cT1 · LiverMultiScan · Hepatica
Primary sclerosing cholangitis. A chronic, progressive disease of the bile ducts, inflammation and scarring narrow the ducts and ultimately damage the liver. Closely associated with inflammatory bowel disease.
Why it matters: PSC is one of the clearest indications for MRCP+. Quantifying duct dimensions over time is the cleanest way to monitor progression without sending patients back through ERCP.
See also: MRCP+ · MRCP · ERCP
Real-world data and real-world evidence. Information collected from sources outside formal clinical trials, registries, electronic health records, insurance claims, observational studies.
Why it matters: regulators (FDA, MHRA, EMA) increasingly accept high-quality RWE alongside trial data to support label expansions and post-marketing surveillance. Perspectum's multi-organ registries, built on CoverScan, are a leading example of imaging-grade RWE.
See also: CoverScan
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