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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5528_Библиотеки_им_академика_М_И_Перельмана.pdf
220 M. M. Shevchuk
Figure 2. Optical biopsy of bladder mucosa using probe-based confocal laser endomicroscopy
(CLE). CLE of normal, low-/high-grade papillary bladder cancer, CIS, and inflammation shown with
corresponding white-light cystoscopy (WLC), and hematoxylin and eosin (H&E) staining of the biopsy.
Low-grade cancer shows characteristic organized papillary structure, whereas high-grade cancer and
CIS show pleomorphic cells anddistorted microarchitecture. Inflammatory mucosa shows lymphocytic
infiltrates. Adapted from Ref. [2].
et al.
accurately staged by OCT and confirmed histologically by biopsy. Similar
results were reported by Karl et al., who demonstrated a 100% sensitivity
for the identification of bladder lesions as malignant by OCT, using histology as the standard.
7
OCT imaging was also able to accurately stage
all lesions invading beyond the lamina propria. Specificity for the presence of malignancy was 65%. Limitations of OCT include relatively high
false-positive rates, the learningcurve associated with image interpretation,
and the absence of prospective multi-center studies to validate clinical utility. Additional research toward smaller caliber instrumentation with higher
resonance frequency is currently underway.
8
CLE is another technology which is FDA-approvedfor use in urology.
Similar to OCT, CLE is probe-based and can be inserted within the working
channel of standard endoscopes. Commercially available CLE (Cellvizio)
utilizes a 488 nm laser and provides dynamic, high-reso lution, subsurface
imaging of the mucosal surfaces (Figure 2). Image acquisition is based
Genitourinary System 221
on sterilizable probes (0.85 and 2.6 mm).1CLE images are comparable to
conventional histopathology, and CLE was developed initially for enhanced
1,9–11
differentiation of cellular features.
Fluorescein is administered intrav-
esically or intravenously just prior to imaging to serve as a contrast agent.
With the spatial resolution of 1 µm, CLE is capable of differentiating between high- and low-grade lesions and of identifying carcinoma
in situ (CIS). Zlatev et al. reported a 90% agreement of CLE diagnosis as
compared with histology.
1
According to their criteria for CLE diagnosis,
benign urothelium is characterized by large luminal umbrella cells overlying intermediate and basal cells. Low-grade papillary tumors consist of
small uniform cells in papillary arrangements surrounding fibrovascular
cores. High-grade lesions, both papillary and flat CIS, contain tumor cells
which vary in size and shape, are often large, and show a disorganized
architecture.
1
Limitations of CLE include the need for a contrast agent, fluorescein, for imaging as well as the learning curve associated with image
interpretation.
MPM is an IVM technology which relies on the simultaneous absorption of 2 or 3 near-infrared low-energy photons produced via autofluorescence endogenous to the tissue. This auto-fluorescence is driven
by cytoplasmic molecules, mainly NADH, FAD, elastin, and lipofuscin,
12
and the second harmonic generation due to collagen.
MPM can generate
images comparable to microscopic images ranging from 4× to 20× magnification and can image tissue up to a depth of 500 µm in three dimensions.
MPM technology is currently being developed for use in endoscopes and
probes. The architecture of papillary urothelial carcinoma can be visualized
because the central fibro-vascular corecontains collagen, whichis identified
by the second harmonic generation. The grade of multilayered malignancy
may be diagnosed by evaluating the size, shape, and cellular organization
of the tumor cells. An ex vivo pilot study examining the performance of
MPM compared to histology of fresh bladder biopsy specimens (Figure 3)
reported that MPM had a positive predictive value for urothelial neoplasia
of 94%, a negative predictive value for neoplasia of 66%, and a correct
distinction between low grade and high grade was achieved in 68% of the
12
cases.
222 M. M. Shevchuk
(a) (b)
(c) (d)
(e) (f)
et al.
Figure 3. MPM of a high-grade papillary urothelial carcinoma of the bladder with corresponding
H&E image. Low magnification MPM (a) and H&E (b) images highlighting the papillary nature of the
lesion with an arrow marking the thin fibrovascular core. MPM (c) and H&E image (d) at intermediate
magnification. MPM (e) and corresponding H&E image (f) at high magnification demonstrating cells
with marked pleomorphism. Adapted from Ref. [12].
Another ex vivo study assessed the use of MPM in diagnosing flat
urothelial lesions, resulting in a 99% accuracy in distinguishing benign
from malignant urothelium, with 97% and 100% sensitivity and specificity,
respectively.
13
Although nuclei are seen as blanks by MPM, their sizes,
shapes, and ratios relative to the surrounding auto-fluorescent cytoplasm
Genitourinary System 223
may be used to distinguish high-grade CIS cells from benign urothelium.
Limitations of MPM include the need of adoption for in vivo applications
and limited depth of imaging penetration.
Upper Urinary Tracts
Upper tract urothelial carcinoma (UTUC), including the pyelocaliceal system and ureters, accounts for 5–10% of all urothelial carcinoma.
3
The
majority of these malignancies are found within the pyelocalicealcollecting
system and are invasive at the time of diagnosis.
14
Diagnostic ureteroscopy
is typically performed to visualize lesions identified via either crosssectional imaging or selective cytology obtained at the time of cystoscopy.
Biopsy yield of ureteroscopy can be poor despite advances in technique,
and obtained tissue fragments are often disrupted and distorted, increasing
15
the difficulties for histologic diagnoses.
Undergrading of UTUC is particularly concerning given that low-grade tumors may be managed with endoscopic ablation and surveillance, whereas high-grade and invasive tumors
14
often prohibit renal-sparing therapies.
Invasive UTUC portends a poor
survival prognosis and patients with high-grade or invasive disease typi-
14
cally require nephroureterectomy.
For these reasons, the ability to visualize upper tract lesions in situ with histologic detail is a valuable adjunct
to histopathologic diagnosis and could play a role in improved staging,
surveillance, and selection of patients for renal-sparing therapy.
Bus et al. reported a feasibility study on the use of an intraureteral
OCT imaging system during ureteroscopy in patients with high suspicion
16
of urothelial carcinoma prior to nephroureterectomy.
They were able to
image the entire ureter and identify multifocal tumors and areas of invasion
(Figure 4). OCT staging was concordant with final histopathology, thus
demonstrating the feasibility of OCT use in optical biopsy of UTUC.
Two CLE feasibility studies for UTUC have been published in patients
undergoing ureteroscopy for suspected urothelial neoplasia.
17,18
Mosaic
images were compiled by “stitching” individual CLE images from the
video sequence, thusincreasing the imagefield and enhancinginterpretation
224 M. M. Shevchuk
(a)
(b)
(c)
et al.
Figure 4. Intraoperative in vivo cross-sectional OCT reveals (a) ureter with protrusion
into lumen (white arrow). Individual tissue layers were seen with protrusion (white arrow). Basal
membrane is visible as a thin dark line under protrusion (pound sign), suggesting non-invasivetumor.
Corresponding histology revealed TaG1-2 urothelial cancer (black arrow). In normal ureter wall (b),
individual tissue layers were identified as urothelial layer (white asterisk and arrow) and basement
membrane (white pound sign and arrow). Corresponding histology revealed same findings (black
asterisk, pound sign, and arrows). 3D pullback of OCT (c) built from 520 individual cross-sectional
images over 5.2 cm length. Suspected tumor regions (green areas) are segmented. Adapted from
Ref. [16].
(Figure 5). Diagnostic criteria in the upper tracts were found to be identical to those for CLE diagnosis within the bladder (Figure 6). Breda et al.
demonstrated that CLE performed at the time of ureteroscopy resulted in
correspondence to final histopathologic diagnosis in 100% of low-grade
UTUC, 83% of high-grade UTUC, and 100% of UTUC CIS.
19
There is a
need for adjunct diagnostic tools for in vivo characterization of upper tract
Genitourinary System 225
(a) (b)
(c) (d)
(e) (f )
Figure 5. Demonstration of CLE probe with a standard flexible ureteroscope. (a) The probe within
the working channel of the ureteroscope. (b) Retroflexion of the ureteroscope with the confocal probe
in place. (c) Fluoroscopic view of the confocal probe (white arrow) in the ureteroscope in the right
ureter. (d) White light view of the confocal probe in the ureter along a standard guidewire. (e) Confocal
laser endomicroscopy (CLE) imaging of normal renal calyx and (f) papillary tumor in the renal pelvis.
Adapted from Ref. [17].
226 M. M. Shevchuk
(a) (b)
(c) (d)
Figure 6. In vivo CLE and corresponding H&E images of high-grade upper tract urothelial carcinoma
in the renal pelvis. CLE images are reminiscent of H&E with the visualization of pleomorphic cells
and papillary features (a, c) and fibrovascular stalks (b, d). Adapted from Ref. [15].
et al.
lesions given the technical challenges associated with obtaining adequate
tumor specimens and the impact this has on candidacy for renal-sparing
therapy. Initial studies with OCT and CLE systems are promising and additional research is needed to prospectively validate these tools and identify
the most appropriate technology for each clinical setting.
Kidney
Renal tumors represent a range of diagnoses, from benign simple cysts
to aggressive malignancies. Resected renal masses under 4 cm in size are
found to be benign in 20% of the cases.
most commonly diagnosed malignancy of the kidney. Tumor size, stage,
20
Renal cell carcinoma (RCC) is the
Genitourinary System 227
grade, and pathologic subtype serve as prognostic factors in RCC.20The
management of renal masses is determined according to risk and patientfactors and may consist of biopsy, active surveillance, renal-sparing therapies,
or radical nephrectomy. Improvement in radiological imaging technology,
combined with growing utilization of cross-sectional imaging, has resulted
in increased detection of small, localized renal masses.
21
The management
of these tumors poses both diagnostic and treatment challenges. In patients
who elect to pursue either active surveillance or ablative therapies, accurate
histologic diagnosis will guide treatment and surveillance decisions. Those
with small renal masses who elect to pursue surgical therapy are frequently
candidates for renal-sparing, partial nephrectomy.
20
During renal-sparing
surgery, it is important to identify the tumor intraoperatively, to distinguish
benign kidney parenchyma from malignant tissue, and to evaluate margin status after resection. Traditionally, tumor localization is done using
intraoperative ultrasound guidance, and margin status is evaluated either
by frozen section or by final histology.
IVM technologies are currently being investigated in clinical
feasibility studies to evaluate their usefulness in identifying renal mass histology, distinguishing benign from malignant lesions, and evaluating resection margins. Most of these studies are in the ex vivo setting, in which the
22
imaging is performed on resected tumor and margin specimens.
Confocal
microscopy, both in the form of CLE and confocal fluorescence microscopy,
has shown promising results in identifying renal neoplasms and in determining histologic subtypes (Figure 7).
22,23
In ex vivo feasibility studies using full-field OCT (ff-OCT), which creates OCT images in cross-section, investigators have distinguished benign
from malignant renal tumors and have characterized features of varying
24,25
pathologic subtypes of RCC (Figure 8).
In vivo application remains to
be demonstrated.
Ex vivo feasibility studies of MPM have been conducted to evaluate
the feasibilityof identifying and classifyingrenal tumors. In 2016, Jain et al.
imaged kidney tissue with MPM immediately after resection and were able
26
to distinguish benign renal parenchyma from malignant tissue.
In addi-
tion, they were able to characterize histologicsubtypes (Figure 9). Clear cell
(a) (b)
(i) (j)
(q) (r)
228 M. M. Shevchuk
(c) (d)
(e) (f )
(g) (h)
(k) (l)
(s) (t)
(m) (n)
(u) (v)
(o) (p)
Figure 7. H&E and corresponding CLE images of normal kidney on the far left, benign renal lesions in the middle, and malignant tumors on the
far right. Normal glomerulus and tubules (a and b), renal pyramid (c and d), renal pelvis (e and f), and sinus fat (g and h). Benign renal tumors,
including angiomyolipoma (i and j), oncocytoma (k and l), cystic nephroma (m and n), and leiomyoma (o and p). Malignant renal tumors, including clear
cell (q and r), papillary (s and t), and acquired cystic (u and v) RCC. Adapted from Ref. [22].
et al.
Genitourinary System 229
(a) (d)
(b)
(c)
Figure 8. Normal renal cortex demonstrated on the left. En face OCT image at a depth of about
150µm (a) and corresponding histological section (b) demonstrate architectural features of normal
cortex, including glomeruli (g) and convoluted tubules (t ). Cross-sectional OCT (CX-OCT ) image (c)
corresponds to scanning position marked as a white dashed line in (a). Clear cell renal cell carcinoma
demonstrated on the right. OCT image at a depth of about 50µm (d) of tumor interface with adjacent
normal tissue and corresponding histological section (e). Arrows indicate hyposcattering features
often seen in tumors (d). Cross-sectional OCT (CX-OCT ) image at scanning position marked as a
white dashed line in (d) reveals differences in imaging depth between normal tissue (n) and tumor
(tu) (f). Adapted from Ref. [25].
(e)
(f)
carcinomas demonstrated a solid architecture with cytoplasmicfat droplets
identified by MPM. Chromophobe RCC also had a solid architecture, with
a distinct granular cytoplasm and lacked fat droplets. Papillary carcinoma
showed a single layer of tumor cells on papillary fibrovascular cores, which
contained collections of bright histiocytes. Papillary urothelial carcinoma
contained a multilayered neoplastic proliferation surrounding the papillary cores. Another study using MPM imaging and morphometric analysis
reported on the feasibility of distinguishing malignant chromophobe renal
cell carcinoma from benign oncocytoma in fixed, unstained, deparaffinized