Why Fidelity Is Becoming the Defining Issue in Modern Radiology
Modern imaging is extraordinary. MRI has the capacity to detect millimetre-scale biological change, and diffusion imaging can reveal tumour cellularity before structural morphology visibly shifts. The physics required to identify early disease already exists.
What is less widely appreciated is that the system delivering that technology is not funded according to what it detects, but according to what it performs. In Australia, radiology reimbursement is tied to the act of scanning – the completion of the study – rather than to detection rates, sensitivity for clinically significant cancer, or reduction in false negatives.
That structural reality has important consequences. As radiology becomes increasingly corporatised, economic efficiency becomes a governing force. Efficiency naturally favours shorter protocols, standardised acquisition, and higher daily throughput. These are rational business pressures. But biological detection does not respond to efficiency metrics. [1]
Cancer does not progress according to appointment schedules. It declares itself only when the imaging is performed with sufficient fidelity to reveal it.
And fidelity – not volume – is what ultimately determines whether early disease is seen or missed.
Can a Prostate MRI Miss Cancer?
This question is searched thousands of times each year.
The answer is: yes – it can.
Prostate MRI accuracy depends heavily on how the scan is performed. Sensitivity for clinically significant prostate cancer is strongly influenced by diffusion parameters, spatial resolution, signal-to-noise ratio, distortion correction, and acquisition time. [2,3]
Published literature demonstrates that prostate MRI sensitivity varies meaningfully depending on diffusion-weighted imaging quality and protocol design. Detection of clinically significant disease (particularly lesions under 15 mm) is highly dependent on acquisition fidelity. Variations in b-value selection, echo spacing, and voxel size can materially alter conspicuity of restricted diffusion and lesion detection rates.
In other words:
A prostate MRI is not a single standardised product. Its accuracy depends on execution – and this holds true for all imaging.
A Prostate Cancer Case That Should Make Us Pause
This patient believed he was doing everything right.
- Elevated PSA
- Urologist oversight
- Serial “dedicated” prostate MRIs
- Reassured imaging
In May 2023 the corporate imaging report concluded:
“No definite area of high grade PCa (prostate cancer) identified.”
Again in August 2024, the radiologist report concluded:
“No significant change in the appearance as compared to the Mp MRI [multi-parametric MRI] May 2023. “No […] evidence of clinically significant prostate cancer. No aggressive lesion is seen…”
From a surface perspective, surveillance appeared appropriate. But there is a critical principle in diagnostic imaging:
A radiologist can only report what is visible. A scan can only reveal what its technical precision allows it to resolve.
The question is not simply whether disease was reported. It is whether the scan was performed at sufficient fidelity to detect disease at that stage of its evolution.
Whole Body MRI vs Dedicated Prostate MRI
Five months later – for unrelated, proactive health reasons – the patient underwent a Whole Body MRI.
There was no sudden PSA rise.
No new symptoms.
No clinical escalation.
He was simply being proactive with his health – and, fortunately, he was.
Importantly, a dedicated prostate MRI should outperform a whole body MRI for detecting prostate cancer.
This is because full body MRI scans covers a much larger anatomical territory, and as a result, allocates less time to any single organ. Additionally, it is typically not contrast enhanced scan for screening purposes.
In theory, these factors should reduce sensitivity for small-organ oncology. However, in this case, the opposite occurred.
The diffusion acquisition in the our Whole Body MRI protocol was performed at markedly higher fidelity – with superior signal-to-noise, optimised b-value execution, and improved distortion correction.
As a result, sensitivity to prostate oncology was materially higher. Several foci of restricted diffusion were clearly visible on our Whole Body MRI scan that had not been identified on the prior “dedicated” prostate studies.
A subsequent high-fidelity dedicated prostate MRI confirmed multiple lesions including clinically significant prostate cancer (PI-RADS 4).
The cancer had almost certainly been present during prior surveillance. Although the prior study was technically complete, but biologically underpowered.
Not All Imaging Is Equal
Two scans performed at different providers can both:
- Meet Medicare item requirements
- Generate compliant reports
- Satisfy billing criteria
- Be labelled as the same type of scan
And yet differ meaningfully in diagnostic sensitivity. Compliance and completion does not equal sensitivity, accuracy, or early detection.
Acquisition fidelity including resolution, signal strength, diffusion parameters, motion control, machine capability and time allocated to data acquisition ultimately determines whether subtle disease is seen or missed.
Despite the importance, these factors are often invisible to patients (and their referring doctors).
Why This Matters for Early Cancer Detection
Cancer is biologically heterogeneous. Some lesions are indolent. Some are clinically significant. Some are small but aggressive.
Early detection of clinically significant cancer – particularly lesions under 10 mm – materially alters management pathways.
A false-negative MRI does not simply delay detection, it delays intervention and treatment which can have significant implications in treatment outcomes.
The Uncomfortable Reality
Under the current Medicare Benefit Schedule in Australia, radiology providers are reimbursed:
To perform the scan.
To generate the report.
They are not reimbursed based on detection performance. There is no Medicare premium for higher acquisition fidelity.
As economic pressure increases, the incentive to shorten protocols and standardise to minimum viable duration grows stronger.
The system rewards efficient volume. Yet, early detection rewards precision.
Those incentives are not aligned.
Conclusion
If you are undergoing prostate MRI for elevated PSA, cancer screening, or surveillance, ask how the scan is performed. Imaging quality depends on acquisition time, diffusion-weighted imaging parameters, spatial resolution, and signal optimisation.
You can take your referral anywhere. In Australia, patients are free to choose their imaging provider. Before booking, ask about scan duration and whether the protocol is designed to maximise sensitivity for clinically significant prostate cancer. Early cancer detection depends not only on having a scan, but on how that scan is performed.
To book your 3T MRI Prostate Scan at MBR Health (formerly Mermaid Beach Radiology), please contact our friendly reception team. Visit our Whole Body MRI website to learn more about our next-generation head to toe imaging.
Author: K Sherif, PhD
Disclaimer: The views expressed in this article reflect the author’s professional perspective on imaging quality and health system design. They are not directed at individual practitioners, but at structural incentives that influence clinical practice. This article is provided for general educational purposes only and does not constitute medical advice. Imaging decisions and cancer surveillance should always be discussed with your treating doctor or specialist. Individual clinical circumstances vary.
References:
1) Fiona M. Fennessy, Stephan E. Maier, Quantitative diffusion MRI in prostate cancer: Image quality, what we can measure and how it improves clinical assessment, European Journal of Radiology, Volume 167, 2023, 111066, ISSN 0720-048X, https://doi.org/10.1016/j.ejrad.2023.111066.
2) Christopher C Conlin, Tyler M Seibert, Anders M Dale, Optimal protocol design for diffusion-weighted imaging of the prostate: an estimation theory examination of parameter estimate variance, medRxiv 2022.02.26.22271561; doi https://doi.org/10.1101/2022.02.26.22271561
3) Docking S, Lacy-Nichols J, Hensher M, Buchbinder R. (2025) Corporatisation and ownership concentration in diagnostic imaging: an audit of Australian practices. Australian Health Review 49, AH25073. https://doi.org/10.1071/AH25073
