JAMA FPS JAMA Facial Plastic Surgery · 2019

Comparison of Micro-Computed Tomography and Clinical Computed Tomography Protocols for Visualization of Nasal Cartilage Before Surgical Planning for Rhinoplasty

Saxena RC, Friedman S, Bly RA, Otjen J, Alessio AM, Li Y, Hannaford B, Whipple M, Moe KS.

PubMed 30730533 Publisher (DOI)Free full text (PMC)

What this paper says

In a single cadaver nose, high-resolution micro-CT showed all three nasal cartilages accurately against the tissue reference, while clinical CT scanners could reliably distinguish only the septal cartilage.

Overview

There is no imaging standard for showing nasal cartilage before rhinoplasty, which limits objective planning. This anatomic study scanned one cadaver specimen with a research micro-CT and with five clinical CT protocols, then sectioned the specimen to compare each scan against what was actually there.

Sections of note

Anatomic study at the University of Washington using a single human cadaveric nasal specimen, July 10, 2017 to March 30, 2018.
A micro-CT acquisition at 60-micron resolution was obtained, then the specimen was scanned with 5 different clinical CT protocols spanning routine care and machine limits.
The specimen was sectioned into 5 mm axial slices for tissue analysis, with images registered using a graphite marker system.
Micro-CT accurately delineated lower lateral, upper lateral and septal cartilage against the tissue findings.
Mean absolute deviation from tissue findings: 0.30 mm for septal cartilage thickness, 0.98 mm for maximal upper lateral cartilage length, 1.40 mm for maximal lower lateral cartilage length.
On clinical CT protocols, only septal cartilage was well distinguished from its boundary.
Higher radiation dose gave more accurate density measurements but did not improve the ability to distinguish cartilage.

What it means for a patient

Ordinary CT scans cannot show the tip and sidewall cartilages clearly enough to plan surgery around them.
Raising the radiation dose does not solve that, so more scanning is not the answer.
Micro-CT achieves it but is a research instrument, not something a patient can be scanned with.
Limits: one cadaver specimen, so the measurements are not a sample from which variation can be estimated.

Why this paper matters

Computer-assisted planning and 3D printing for rhinoplasty depend on being able to image the cartilage, and this establishes that current clinical scanners cannot. It identifies the specific barrier to be solved. Until it is, patient-specific planning is limited to surface shape rather than the framework beneath.

Terms

Micro-computed tomography: A very high resolution CT used on specimens rather than patients.
Hounsfield unit: The density scale used in CT imaging.
Fiducial marker: A reference point placed to align images with the physical specimen.
Segmentation: Outlining a structure within an image so it can be measured.
Upper and lower lateral cartilage: The cartilages forming the middle nose and the tip.

Summary written by rhinoplasty.cc from the abstract, 2026-09-09; not medical advice. The authors' own abstract follows.

Abstract

Importance: There is no imaging standard to model nasal cartilage for the planning of rhinoplasty procedures. Preoperative visualization of cartilage may improve objective evaluation of nasal deformities, surgical planning, and surgical reconstruction.

Objectives: To evaluate the feasibility of visualizing nasal cartilage using high resolution micro-computed tomography (CT) compared with the criterion standard of pathologic findings in a cadaveric specimen and to evaluate its accuracy compared with various clinical CT protocols.

Design, Setting, And Participants: Anatomic study at the University of Washington using single human cadaveric nasal specimens performed from July 10, 2017, to March 30, 2018.

Interventions: A micro-CT acquisition with 60-micron resolution was obtained of a nasal specimen. The specimen was then scanned with 5 different clinical CT protocols to span both clinical care and machine limits. The specimen was then sectioned in 5-mm axial slices for pathologic analysis.

Main Outcomes And Measures: Micro-CT images were registered to pathologic specimen cross-sections using a graphite fiducial system. Cartilage substructures were manually segmented and analyzed. A library of matched images across the micro-CT and various clinical CT protocols was then developed. Region of interest analysis was performed for each of the cartilage structures and their boundaries on clinical CT protocols and micro-CT, with the outcome of mean (SD) density using Hounsfield units.

Results: A single human cadaveric nasal specimen was used to obtain the following results. Lower lateral cartilage, upper lateral cartilage, and septal cartilage were accurately delineated on the micro-CT images compared with pathologic findings. The mean absolute deviation from pathologic findings was 0.30 mm for septal cartilage thickness, 0.98 mm for maximal upper lateral cartilage length, and 1.40 mm for maximal lower lateral cartilage length. On clinical CT protocols, only septal cartilage was well discriminated from boundary. Higher radiation dose resulted in more accurate density measurements of cartilage, but it did not ultimately improve ability to discriminate cartilage.

Conclusions And Relevance: The results of this anatomic study may represent a notable step toward advancing knowledge of the capabilities and pitfalls of nasal cartilage visualization on CT. Nasal cartilage visualization was feasible on the micro-CT compared with pathologic findings. Future research may further examine the barriers to accurately visualizing upper lateral cartilage and lower lateral cartilage, a prerequisite for clinical application.

Level Of Evidence: NA.

Abstract as indexed by PubMed; the article is open access (PubMed Central).