Cochlear implants
Cochlear implants (CIs) bypass damaged or nonfunctional parts of the ear and directly stimulate the auditory nerve. UHR imaging is often used in the workup prior to and assessment after their deployment. The detailed information provided by UHR imaging helps assessing candidates, and in the planning of the procedure, supporting the accurate and effective placement of the implant. After the implant has been placed, it can help verify the position of the electrodes within the cochlea. This allows for the implant to be positioned correctly, functioning as intended, and may detect other complications (e.g., cochlear ossification) [7].
Quantum HD has the potential to not only reduce the dose of UHR imaging in cochlear implant assessment compared to EID-CT, but can also improve the overall image quality. In contrast with conventional EID-CT, Quantum HD reduced dose by an average of 22% while having significantly better visualization. “Compared to multi-detector CT, the visibility of the normal temporal bones scored better with PCCT” [8]. Indeed, Jeremy Wales, ENT specialist and Senior Researcher in Otology at Karolinska University Hospital, Sweden, says “NAEOTOM Alpha with Quantum HD imaging enables visualization of the exact CI electrode placement within the cochlea while also minimizing the radiation dose.”
Figure 9 and Figure 10 provide examples of the high image quality Quantum HD brings to the visualization of cochlear implants.
Figure 9: Bilateral implants, Quantum HD. 120 kVp | CTDI: 11 mGy | MPRs | 0.2 mm | Hr72. Courtesy of University Hospital of Karolinska, Stockholm, Sweden.
Figure 10: CT imaging of the skull base for stapes implant follow-up. Quantum HD | CTDI: 55 mGy | QIR strength: 3. Courtesy of Erasmus Medical Center Rotterdam, Rotterdam, Netherlands.
Cerebrovascular exams
Quantum HD also has the potential to transform vascular imaging in the head. A comparison of angiographic images of the orbital vasculature between EID-CT (Dual Energy 100/Sn 150 kV) and PCCT’s Quantum HD at comparable doses found the “arterial anatomy of the orbit is much better depicted with arterial Quantum HD as opposed to arterial EID-CT” [9]. Furthermore, “Angiographic Quantum HD of the orbit could potentially obviate conventional catheter-based examinations in certain clinical situations where the diagnosis or appropriate follow-up imaging can be made adequately with CTA. Angiographic Quantum HD should also be able to reliably assess for potential collaterals which could contraindicate or modify approach of certain therapeutic interventions.”
In this domain, Quantum HD has demonstrated its utility in a variety of contexts. For example: Figure 11 shows an example of Quantum HD allowing the depiction of micro-calcifications in the ophthalmic and superficial temporal arteries.
Figure 11: Ophthalmic and superficial temporal arteries. Quantum HD | 120 kVp | CTDI: 10 mGy. Courtesy of Erasmus Medical Center Rotterdam, Rotterdam, Netherlands.
Figure 12 shows a carotid artery and a middle cerebral artery stent with dimensions 20 mm long by 2 mm wide. Note the lack of blooming artifact due in part to the high-resolution characteristics of Quantum HD. Figure 13 also lacks any major metal artifacts in Quantum HD mode and maintains the contrast in the small vessels. Figure 14 depicts an aneurysm less 3 mm in diameter.
Figure 12: Stent follow-up. Quantum HD | 120 kVp | CTDI: 10.9 mGy. Courtesy of Dr. Jones & Partners – SAHMRI, Adelaide, Australia.
Figure 13: Flow Diverter. Quantum HD | 120 kVp | CTDI: 14 mGy. Courtesy of Erasmus Medical Center Rotterdam, Rotterdam, Netherlands.
Figure 14: Aneurysm less than 3 mm in diameter. Quantum HD | 120 kVp | CTDIvol: 14.5 mGy | DLP: 261 mGy*cm. Courtesy of Erasmus Medical Center Rotterdam, Rotterdam, Netherlands.
Lacrimal duct imaging
Quantum HD is also capable of imaging beyond the vasculature to evaluate the patency of the lacrimal duct. Figure 15 depicts a case study of a patient whose lacrimal duct was not filling. The stakes in this case were high since the patient, after extensive facial reconstruction, had only one eye. If this eye were compromised the patient would be completely blind. A procedure was performed to inject contrast into the duct and follow its path. PURE Lumen was applied to the spectral reconstruction as well to virtually remove any microcalcifications.
Figure 15: Contrast agent injected into patient’s lacrimal duct to evaluate patency. Pre-contrast scan: CTDI 7.79 mGy; post-contrast scan: Quantum HD CTDI 21.4 mGy. Courtesy of Erasmus Medical Center Rotterdam, Rotterdam, Netherlands.