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HistoScanning™ and Its Role in Prostate Cancer Diagnosis, Staging, Treatment and Monitoring
Table 1: The Usefulness of Various Imaging Technologies for Figure 1: Identifying Differentiated Tissue
Prostate Cancer Diagnosis, Staging and Monitoring Treatment
Technology Benefits Limitations
TRUS • Easy, available, quick, safe • Variable specificity
and cheap. (50–90%)
5,6
and
• Good visualisation sensitivity (48–86%)
6
of palpable tumours • 30% palpable tumours
• Useful for guiding biopsies not visualised
and prostate volume studies
4
• Rarely detects small
(<5mm) lesions
• Low local staging capability;
unable to show EPE
7
Colour and power • Specificity better than • Sensitivity only a little
Doppler US greyscale US for lesions better than greyscale US
>1cm in transition zone • Cannot detect small
• Relatively accessible lesions (<5mm) with
and affordable micro-neovascularity
8
Contrast-enhanced • May improve detection of • Inherent weak signals
US smaller (2–5mm) lesions difficult to detect from the
background signals
The large background region (A) is composed of spotted balls, but the coloured area is
• Expensive, time-consuming, composed of dice, and therefore differentiated from the background. However, the two areas
complicated
9 cannot be distinguished visually. Differentiating the group of dice is not possible even if the
picture is enlarged, because information has already been lost in the display process. The
• May require pre-medication
original data captured to create this picture contain all of the necessary information needed for
to reduce blood flow
10
differentiation, such as different reflection characteristics between spheres and cubes and the
Sonoelastography • Yields a colour mapping • Relatively low sensitivity
resolution required to recognise the different patterns. Mathematical and statistical analysis of
all of the original data captured would reveal the difference between areas B and C. Similarly,
of tissue elasticity (68%) and specificity (81%)
11
HistoScanning analyses all of the source data underlying the digital ultrasound image and
• Relatively affordable • Examiner-dependent
12 would reveal the differentiated area in the ultrasound image, allowing it to be highlighted.
• Poor at detecting posterior
tumours
12
detection, characterisation and visualisation of differentiated tissue,
• Narrow dynamic elasticity
range of the prostate
12
such as prostate cancer lesions. For any tissue characterisation
Computed • Often used to look for • Lacks soft-tissue
technology to deliver consistent and optimal results it is important that:
tomography lymph node involvement contrast resolution
• Unable to distinguish
• data collected are standardised and user-independent; and
malignant from
• early source data are used for analysis. (Data compression, dynamic
non-malignant zones
13
range mapping and filtering all result in the irreversible loss of
• Relatively expensive and not
important information.)
universally available
MRI and MRSI • Accurate for staging disease • Low sensitivity
14
• High specificity
14
• BPH may obscure lesions
For this reason, the latest version of the HistoScanning technology uses
• Able to detect EPE, seminal in the transition zone
17
radiofrequency (RF) ultrasound data straight from a transducer that is
vesicle, bladder or rectum • Expensive and therefore capable of acquiring volume RF (native) data in a standard way. This
invasion
14,15
not universally available
is significantly richer in information than the raw or grey-level data that
• Useful for treatment planning • MRSI (citrate reduction) may
are displayed by ultrasound machines, and is not affected by any of the
• MRSI increases staging accuracy confuse prostatitis or
machine’s user settings. Statistical and mathematical analysis of all of
and reduces interobserver post-biopsy haemorrhage
variability
16
with cancer lesions
18
the data captured from such an ultrasound transducer makes it possible
Positron emission • Can detect metastatic • Uptake of radiotracer
for HistoScanning to identify differentiated tissue and assess the size and
tomography disease 18-FDG may vary when
accurately locate the site of the differentiated tissue. Thus, potentially,
cancer present
19
changes in specific lesions between one follow-up and the next can be
• Inability to distinguish scar
quantified. Figure 1 illustrates this process.
tissue from local recurrence
post-prostatectomy
20
Seeing Is Believing – The Need for Clinical Evidence
• At best provides similar
As discussed earlier, all existing diagnostic imaging technologies appear
information to TRUS or MRI
21
• Expensive and not
to lack at least some of the key characteristics required to meet current
widely available
or anticipated clinical diagnostic needs. Furthermore, it is difficult to draw
TRUS = transrectal ultrasound; EPE = extraprostatic extension; US = ultrasound;
direct comparisons between the different technologies in terms of
CT = computed tomography; MRI = magnetic resonance imaging; MRSI = magnetic resonance
sensitivity and specificity due to the methodological differences in the
spectroscopy imaging; BPH = benign prostatic hyperplasia.
published studies (see Table 2
11,22,23
). However, from the review of
constraints imposed on them in order that they can be visualised on a the literature presented by Mark Emberton, it would appear that only
computer display, an additional two orders of magnitude of detail have dynamic contrast-enhanced MRI (DCE-MRI) comes close to meeting the
been irretrievably ‘lost’ in the process. New technology such as standards required clinically, but it still falls short of an ideal sensitivity or
HistoScanning may harness this otherwise ‘unused data’ to enhance the specificity, even for lesions ≥0.5cc.
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