The series of scans yielded the following results for the water (Fig. 5) and the dilute contrast series (Fig. 6).

Fig. 5: Water only series results

Fig. 6: Dilute contrast series results

NOTE : Decrease in contrast resolution with increase in keV

(K-edge of Iodine - 33.2keV)

 Table 1 summarises the average Hounsfield units ascertained via the Siemens Healthcare, Syngo VIA VB20 software program. The variation between the water and contrast baths highlights the effect of the pseudo-enhancement.

Table 1: Summary of Results - Hounsfield Units (HU)

 Whilst the contents of the PVC pipes have not been changed, the HU has erroneously increased from 0 HU to 17 HU when bathed in contrast material. A false or pseudo-enhancement has occurred through the iterative reconstruction process in conjunction with the beam hardening and partial voluming, when there should be no change to the HU.

 The contrast to noise ratio for a standard 32cm CT water phantom scan is best at approximately 70keV (dependent on patient size and dose delivered). As demonstrated in figure 7, mono-energetic images in the range of 110keV to 150keV are well suited to minimise pseudo-enhancement.

Fig. 7: Optimal contrast to noise ratio as demonstrated by the Siemens Syngo VIA VB20 system
References: Siemens Healthcare - Syngo VIA VB20, Siemens Healthineers, Forchheim Germany

 The impact and use of the HU for the management and definition of Renal Cysts and Masses is well defined by the Bosniak Classification system (Fig. 8). The radiological features of enhancement and appearance assists to determine the most appropriate management of the masses itself.

Fig. 8: The Bosniak CT Classification of Renal Cysts
References: Cystic Diseases of the Kidney CNE Ahmed Hassan Mohamed MD Lecturer of nephrology National institute urology & nephrology NIUNESNT-CNE 1st Course, Cairo, Sept 10-14, 2012

Table 2: Renal mass enhancement criteria
References: http://www.radiologyassistant.nl/en/p44d1045b472df/kidney-cystic-masses.html

 As illustrated in Table 2, an enhancement of between 10 - 15 HU would require additional follow up whilst an enhancement of > 15 HU may well push the mass into the excise category.

 The results also indicate that using virtual mono-energetic images ranging from 120keV to 130keV are the best at eliminating this pseudo-enhancement. This is indicated by the 0.6 HU increase and -0.6 HU decrease from the true HU at the respective keV energies (Table 1).

 Case studies 1 and 2 below highlight the real-time effects of pseudo-enhancement and provide strong evidence that the use of Dual-Source Dual-Energy scanning assists to classify and clarify renal masses more definitively.

Fig. 9: Case Study 1
References: Department of Digital Radiology, Princess Alexandra Hospital, Brisbane Australia

Fig. 10: Case Study 2
References: Department of Digital Radiology, Princess Alexandra Hospital, Brisbane Australia

 Case study 3 highlights the use of Dual-Source Dual-Energy scanning protocols by providing additional iodine maps to provide crucial information to the Radiologist and the patient's treating team.

Fig. 11: Case Study 3
References: Department of Digital Radiology, Princess Alexandra Hospital, Brisbane Australia