PART THREE
Special Techniques in Cytology
F ig . 3 4 .1 5 F o c a lP o in t re v ie w s c o p e (S lid e W iz a rd ). In th e FocalP oint GS
m o de l, locations o f p o te n tia lly a b n o rm a l cells are id e n tifie d by th e scanning
d evice and tra n sfe rre d to th is sta tio n fo r c y to lo g is t review .
E arly after the FPPS was approved fo r use in the U n ite d
States, th is location-g uid ed screening cap ab ility was exploited
using a m an ua l lo c a tio n transfer m e th o d b y investigators in
Taiw an and H o n g Kong, w ith data show ing overall ab norm al
detection perform ance im p ro ve m e n t w ith substantial gains in
screening p rod u c tivity.102,103 The study b y Chang et al. is also
o f interest because the fin a l in te rp re ta tio n was m ade using the
FO V review only, n o t triag ing the slide to a fu ll m anual review
w h e n an a b n o rm a lity was in itia lly detected. T his study showed
the im p ortance o f the triaging process, because a lth ou g h an
ab norm al in te rp re ta tio n was capable o f being m ade using FO V
review alone, the fin a l diagnosis rendered was in som e cases n o t
at th e level o f a b n o rm a lity ob tained w h en the entire slide was
reviewed. T his study illustrates the need fo r a fu ll m an ua l review
procedure w ith th is location-g uid ed screening device in order to
m axim ize the accuracy o f the fin a l in te rp re ta tio n .103
In a tw o-arm ed m asked prospective stud y using th is device
w ith an integrated rob o tic m icroscopy sta tio n (Fig. 34.1 5 ) th a t
allow ed fo r autom ated lo c a liza tio n and review o f the device-
selected FOVs, data showed th a t 100% o f adjudicated HSIL+
slides were ap p rop riately triaged to m anual review. A fte r m an -
ual review, 98% were correctly forw arded fo r p atho lo g ist review
using th is system, as com pared w ith 91% w ith m an ua l screen-
ing alone. In th is study, again, a gain in specificity o f ab norm al
case detection was also n ote d .104 Furth er studies have confirm ed
the equivalence o f the FocalP oint location-g uid ed screening sys-
tem to m anual screening fo r the detection o f H SIL+ 105,106 and
SIL+.107
T he device ensures th a t the lo c a tio n id en tifie d on the rob o tic
m icroscope is as intended via the use o f images captured at the
selected FO V sites d uring the screening process. These images
are displayed o n the m o n ito r fo r the review er at th e w o rk -
sta tio n to c on firm th a t the proper loc a tio n is being viewed
in the m icroscope (Fig. 34.1 6 ) .
A t present, th e FocalP oint GS location-g uid ed screening
system is in clinical trials fo r use in the U n ite d States.
The Cytyc ThinPrep Im aging System
In 2003, an approval was granted b y the U S FD A fo r the T h in -
Prep Im aging System. T h is device is a location-g uid ed screen-
ing in s tru m e n t th a t is m ated to T hinP re p liquid-based slides.
T he device is a personal com puter-based system designed to be
F ig . 3 4 .1 6 F o c a lP o in t re v ie w s c o p e c o m p u te r s c re e n , sh ow in g
n a vig a tion to o ls and re p o rtin g m enus. The slide im age sh o w in g locations
is at th e b o tto m o f th e fie ld , and th e black and w h ite im age saved by th e
FocalP oint ensures th a t th e fie ld o f v ie w prese n te d by th e re vie w station is
th e actual area o f h ig h p ro b a b ility d e sig n a te d by th e device.
F ig . 3 4 .1 7 C y ty c T h in P re p Im a g in g S y s te m d e v ic e . This is a personal
c o m p u te r-b a s e d m u ltilo a d "w a lk aw ay” d evice th a t consists o f a ro b o tic
scanning m icrosco p y sta tio n in to w h ic h cassettes o f slides are placed.
located w ith in the clinical cytology laboratory. The scanning
com p uter (Fig. 34.1 7 ) is loaded w ith cassettes o f T hinP re p slides
and scanning proceeds in a w a lk away m an ne r w ith a rob otic
microscope. The com p uter analysis is designed around a special
P ap anicolaou-like stain th a t is sto ic hiom etric fo r th e D N A con-
te n t o f cell nuclei. Thus the device p rim a rily perform s a D N A
analysis on each cell, lo o k in g fo r cases w ith ab norm al D N A con-
tent. As is w e ll k n o w n fro m num erous p rio r studies dating back
m an y years, the D N A content o f dysplastic and neoplastic cells
is n o t d ip lo id and hence detection o f n o n d ip lo id cells in the
sam ple indicates a risk o f ab norm ality. In a d d itio n, o th e r m o r-
p h om etric param eters such as cell size and shape are also rep o rt-
edly included in the cellular analysis. The device id entifies 22
FOVs per ThinP re p slide and transfers these locations to a com -
puterized m icroscopy review sta tio n (Fig. 34.1 8 ) . The cytologist
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