Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1515_Библиотеки_им_академика_М_И_Перельмана
.pdf
MRI in Inflammatory Small-Bowel Diseases 5
ed the role of MRI in the evaluation of the gastroin-
testinal tract. Various MR sequences for evaluating
the gastrointestinal tract have been advocated by dif-
ferent authors. However, no sole sequence can be
used for comprehensive imaging of Crohn’s disease,
as each sequence has its specific advantages and lim-
itations. Therefore, it is essential to use a compre-
hensive examination protocol in which disadvan-
tages of one sequence can be compensated by the
advantages of the others.
Fast Spin Echo T2-Weighted Sequence
Half-Fourier acquisition single shot turbo spin echo
(HASTE) demonstrate lack of magnetic susceptibil-
ity artifacts and lack of artifacts from bowel peri-
stalsis theoretically making the HASTE sequence
ideal for imaging bowel. A limitation of HASTE is its
sensitivity to intraluminal flow voids, while another
disadvantage is that no information on mesenteries
can be obtained due to K-space filtering effects
(Fig. 1).
True-FISP Sequence
Another sequence promoted for the evaluation of
Crohn’s disease is the true fast imaging with steady-
state precession (true-FISP) sequence, which is a
completely refocused steady-state gradient echo
sequence (also called balanced fast-field echo (Fig. 1).
Motion-related artifacts are minimal due to the short
acquisition time, while at the same time insensitivity
to intraluminal flow voids is observed due to the bal-
anced and symmetric gradient design. The bowel
wall is well visualized due to good differentiation in
contrast (via positive or biphasic contrast agent)
between the hypointense bowel wall and the hyperin-
tense bowel lumen (Fig. 1). The true-FISP sequence is
particularly good for obtaining information about
extra-intestinal complications; the mesenteries are
very well visualized and lymph nodes are very con-
spicuous with this technique. The black boundary
artifact encountered with the true-FISP sequence, at
fat-water interfaces, may hamper the perception of
subtle thickening of the bowel wall.
Gadolinium-Enhanced T1-Weighted Sequence
Many study groups have focused on gadolinium-
enhanced T1-weighted images for assessment of dis-
ease [27-30], as both localization and severity of
inflammation can be appraised with this sequence.
Inflamed bowel segments show pathological
enhancement after administration of intravenous
gadolinium. When combining T1-weighted sequences
with fat suppression and use of intravenous gadolin-
ium-chelates, very good differentiation in contrast is
obtained between the pathologically enhancing
bowel wall and the dark bowel lumen and suppressed
perivisceral fat (Fig. 2). The marked increase in signal
intensity of inflamed bowel after administration of
Fig. 2. Coronal fat suppressed T1-weighted spoiled gradient echo sequence acquired before (a) and 30 s following intra-
venous administration of gadolinium chelate (b), demonstrating marked parietal enhancement of the distal ileal loop
(arrow)
a
b
6 R. Manfredi, R. Malagò, M. Testoni, V. Girardi, R. Pozzi Mucelli
intravenous gadolinium is due to increased tissue
perfusion and vascular permeability (Fig. 2).
MR Enteroclisis Findings
Early lesions of Crohn’s disease such as blunting,
flattening, thickening, distortion and straightening
of the valvulae conniventes and tiny aphthae were
clearly shown at conventional enteroclysis, but they
were not consistently depicted with MR enteroclysis
due to its inadequate spatial resolution. The valvulae
conniventes were shown to their best advantage and
distortion of the mucosal folds was easily detected
with MR enteroclysis.
The characteristic discrete longitudinal or trans-
verse ulcers of Crohn’s disease could be shown at MR
enteroclysis, provided there was satisfactory disten-
tion of the bowel. MR enteroclysis was less sensitive
than conventional enteroclysis in the detection of lin-
ear ulcers due to low spatial resolution and lack of
compression techniques. Thin high-signal-intensity
lines within the bowel wall on true FISP MR images
represented linear ulcers. Cobblestoning was caused
mostly by a combination of longitudinal and trans-
verse ulceration and was easily shown with MR ente-
roclysis. The true FISP sequence was superior to
HASTE in showing linear ulcers, cobblestoning, and
intramural tracts, while the three-dimensional gradi-
ent echo sequence was less satisfactory in depicting
such lesions smaller than 3 mm in diameter.
Bowel-wall thickening was clearly shown with all
MR enteroclysis sequences (Figs. 2, 3). The thickened
wall had moderate signal intensity on true FISP
images and could be easily differentiated from the
black boundary artifact. Bowel-wall thickness and
length of small-bowel involvement could be meas-
ured on MR enteroclysis images. Narrowing of the
lumen and associated prestenotic dilatation were
easily recognized on MR enteroclysis images
obtained with all sequences (Figs. 2, 3). Asymmetric
involvement, pseudo-diverticula formation, and skip
or multiple lesions were easily depicted via MR ente-
roclysis.
Fig. 3. A 57-year-old female with active Crohn’s disease. a, b Axial fat-suppressed true-FISP images show severe thickening
of the terminal ileum with luminal stenosis and fibro-fatty proliferation. c, d After Gadolinium administration fat sup-
pressed T1-weighted spoiled gradient echo images show enhancement of the bowel wall due to Crohn’s disease activity
a
c
b
d
MRI in Inflammatory Small-Bowel Diseases 7
Quantification of Dynamic Contrast-Enhanced MRI
(DCE)
DCE-MRI imaging techniques are still evolving and
methods of image analysis remain mostly qualitative,
variable, and nonstandard, making these techniques
unsuitable for comparisons between different insti-
tutions or different study protocols. In the attempt to
standardize and make this analysis quantitative, a
number of pharmacokinetic multicompartment
models have been proposed that would serve to infer
“absolute” physiological quantities from the data
gathered with the dynamic scan.
When the contrast agent is injected, it equilibrates
with the blood plasma and is rapidly delivered to the
different tissues. The blood plasma (the central com-
partment) and the extra-vascular, extra-cellular
space of the inflamed tissue lesion (the peripheral
compartment) are connected by linear exchange
processes in both directions. The measurement of
microvessel permeability is possible by assessment of
the rate at which a contrast agent transfers from the
blood pool to the extra-vascular extra-cellular space.
Similarly, the transfer of the contrast agent back to
the blood can be expressed as the reflux coefficient.
In addition, the measurement of increased blood vol-
ume is possible by permitting calculation of fraction-
al plasma volume [31]. This method offers the great
advantage of being quantitative, i.e., not measure-
ment-dependent but pathology-dependent, so that
the results from different studies/sites can be direct-
ly compared.
Clinical scoring (such as the Crohn’s disease activ-
ity index [32], biologic indexes [33], endoscopy, and
imaging studies have all been used to monitor activi-
ty, but no established gold standard exists. Assess-
ment of activity is usually made using a combination
of clinical symptoms, physical findings, laboratory
investigations, endoscopy, and imaging tests. The
assessment of biologic activity, based on the positiv-
ity for three of four acute phase reactants (WBC, ery-
throcyte sedimentation rate, and C-reactive protein),
has been found to be a sensitive determinant of activ-
ity, especially when supported by endoscopic or
imaging findings.
Extra-Mural Manifestations and Complications
MR enteroclysis had a clear advantage over conven-
tional enteroclysis in the demonstration of extramu-
ral manifestations or complications of Crohn’s dis-
ease. The extent of fibro-fatty proliferation and its
composition, mostly fatty or mostly fibrotic, could be
assessed with MR enteroclysis, especially when true
FISP images were obtained (Fig. 3). The so-called
comb sign (Fig. 4), corresponding to increased
mesenteric vascularity, could be ideally seen on true
FISP images close to the mesenteric border of a
small-bowel segment in the form of short, parallel,
low-signal-intensity linear structures perpendicular
to the intestinal long axis. The comb sign could be
seen on three-dimensional FLASH images as high-
signal-intensity linear elements.
Small mesenteric lymph nodes were easily detect-
ed by their low signal intensity within the high-sig-
nal-intensity mesenteric fat on true FISP images
(Fig. 5). Their presence was not as obvious with other
MR enteroclysis sequences due to short T2 filtering
effects on HASTE images and to saturation of mesen-
teric fat signal on three-dimensional FLASH images.
Sinus tracts and fistulae were disclosed by the high-
signal intensity of their fluid content on true FISP
and HASTE images, but they could be missed on the
three-dimensional FLASH images due to limited con-
trast with surrounding tissues. All fistulae shown at
conventional enteroclysis were also depicted at MR
enteroclysis, while only half of the sinus tracts were
detected at MR enteroclysis, even in retrospect in our
series. Abscesses could be recognized by their fluid
content and contrast enhancement of the wall. There
were strong indications that disease activity can be
appreciated with MR enteroclysis (Fig. 6) [34, 35].
Conclusions
MR imaging is an emerging technique in this field
and is expected to play a role similar to that of CT.
The clinical efficacy of MR imaging has been investi-
gated, and favorable results have been reported as
described in this article. High soft-tissue contrast,
static and dynamic imaging capabilities, and the
absence of ionizing radiation exposure represent the
advantages of MR imaging over CT. On the other
hand, MR imaging is more time consuming, less
readily available, and more expensive [36–39].
Advantages of CT over MR imaging include greater
availability, shorter examination times, flexibility in
choosing imaging thickness and planes after data
acquisition with multidetector row CT, and higher
spatial resolution. Precise indications for MR imag-
ing in the diagnosis of Crohn’s disease and its use as
a complement to CT or other imaging procedures
need further investigation. Clinical management
decisions might be influenced by the presence of
unsuspected additional lesions that were seen only
on CT or MR imaging, as reported by Fishman et al.
and Turetschek et al., with management changes
occurring in 28 and 62% of cases, respectively. Cross-
sectional imaging should be included or even per-
formed as a primary examination in the clinical eval-
8 R. Manfredi, R. Malagò, M. Testoni, V. Girardi, R. Pozzi Mucelli
uation of Crohn’s disease, along with conventional
imaging and clinical and laboratory tests. Cross-sec-
tional imaging should be used to evaluate for the
presence of entities that indicate elective gastroin-
testinal surgery–e.g., marked prestenotic dilatation
(severe stenosis), skip lesions, fistulae, perforations,
abscesses.
Fig. 4. A 27-year-old man with active Crohn’s disease. a, b On coronal true FISP images Mesenteric vessels (vasa resta) are
clearly detectable depicting the so-called “comb sign” which corresponds to hypertrophied mesenteric vascularisation
perpendicular to the axis of the affected bowel loop (arrow). c, d Contrast enhanced T1-weighted gradient echo images,
confirm disease activity (arrows)
a
c
b
d
MRI in Inflammatory Small-Bowel Diseases 9
Fig. 5. Coronal (a, b) and sagittal (c) fat-suppressed true-
FISP images show thickening of the bowel wall (short
arrows) of the terminal ileum. Small mesenteric lymph
nodes (arrowhead) are also depicted along the vessels
a
c
b
10 R. Manfredi, R. Malagò, M. Testoni, V. Girardi, R. Pozzi Mucelli
References
1. Masselli G, Brizi MG, Menchini L et al (2005) Magnet-
ic Resonance Enteroclysis imaging of Crohn’s. Radiol
Med 110(3):221–233
2. Broglia L, Gigante P, Papi C et al (2003) Magnetic Res-
onance enteroclysis imaging in Crohn’s disease. Radi-
ol Med 106(1–2):28–35
3. Laghi A, Passariello R (2003) Magnetic Resonance in
the study of the small bowel. Radiol Med
106(1–2):1–15
4. Halligan S, Buchanan G (2003) MR imaging of fistula-
in-ano. Eur J Radiol 47:98–107
5. Bell SJ, Halligan S, Windsor AC et al (2003) Response
of fistulating Crohn’s disease to infliximab treatment
assessed by magnetic resonance imaging. Aliment
Pharmacol Ther 17:387–393
6. Van Assche G, Vanbeckevoort D, Bielen D et al. (2003)
Magnetic resonance imaging of the effects of inflix-
imab on perianal fistulizing Crohn’s disease. Am J
Gastroenterol 98:332–339
7. Gourtsoyiannis N, Papanikolaou N, Grammatikakis J,
Prassopoulos P (2002) MR enteroclysis: technical con-
siderations and clinical applications. Eur Radiol
12:2651–2658
8. Low RN, Sebrechts CP, Politoske DA et al (2002)
Crohn’s disease with endoscopic correlation: sin-
gleshot fast spin-echo and gadolinium-enhanced fat-
suppressed spoiled gradient-echo MR imaging. Radi-
ology 222:652–660
9. Low RN, Francis IR, Politoske et al (2000) Crohn’s dis-
ease evaluation: comparison of contrast-enhanced MR
imaging and single-phase helical CT scanning. J Magn
Reson Imaging 11:127–135
10. Mako EK, Mester AR, Tarjan Z et al (
2000) Entero-
clysis and spiral CT examination in diagnosis and
evaluation of small bowel Crohn’s disease. Eur J Radi-
ol 35:168–175
11. Raptopoulos V, Schwartz RK, McNicholas MM et al
(1997) Multiplanar helical CT enterography in patients
with Crohn’s disease. AJR Am J Roentgenol
169:1545–1550
12. Rollandi GA, Curone PF, Biscaldi E et al (1999) Spiral
CT of the abdomen after distension of small bowel
loops with transparent enema in patients with Crohn’s
disease. Abdom Imaging 24:544–549
13. Turetschek K, Schober E, Wunderbaldinger P et al
(2002) Findings at helical CT-enteroclysis in sympto-
matic patients with Crohn’s disease: correlation with
endoscopic and surgical findings. J Comput Assist
Tomogr 26:488–492
14. Umschaden HW, Szolar D, Gasser J et al (2002) Small-
bowel disease: comparison of MR enteroclysis images
with conventional enteroclysis and surgical findings.
Radiology 215:717–725
15. Lee J, Marcos HB, Semelka RC (1998) MR imaging of
the small bowel using the HASTE sequence. AJR Am J
Roentgenol 170:1457–1463
16. Prassopoulos P, Papanikolaou N, Grammatikakis J et
al (2001) MR enteroclysis imaging of Crohn’s disease.
Radiographics 21:S161–S172
17. Debatin JF, Patak MA (1999) MRI of the small and
large bowel. Eur Radiol 9:1523–1534
18. Low RN, Francis IR (1997) MR imaging of the gas-
trointestinal tract with i.v., gadolinium and diluted
barium oral contrast media compared with unen-
hanced MR imaging and CT. AJR Am J Roentgenol
169:1051–1059
19. Umschaden HW, Gasser J (2003) MR enteroclysis.
Radiol Clin North Am 41:231–248
20. Giovagnoni A, Fabbri A, Maccioni F (
2002) Oral con-
trast agents in MRI of the gastrointestinal tract.
Abdom Imaging 27:367–375
21. Papanikolaou N, Prassopoulos P, Grammatikakis J et
al (2002) Optimization of a contrast medium suitable
for conventional enteroclysis, MR enteroclysis, and
Fig. 6. Perirectal fistulas. (a) Coronal T2-weighted rapid
acquisition with relaxation enhancement (RARE) shows a
trans-sphincteric fistula extending into the fatty tissue of
the right ischiorectal fossa and crossing the right elevator
ani muscle. (b) Axial T1-weighted spin-echo image shows a
fistulous tract crossing the anal sphincter and extending
into the adipose tissue of the right ischiorectal fossas
a
b
MRI in Inflammatory Small-Bowel Diseases 11
virtual MR enteroscopy. Abdom Imaging 27:517–522
22. Maccioni F, Viscido A, Marini M, Caprilli R (2002)
MRI evaluation of Crohn’s disease of the small and
large bowel with the use of negative superparamagnet-
ic oral contrast agents. Abdom Imaging 27:384–393
23. Holzknecht N, Helmberger T, von Ritter C et al (1998).
Breathhold MRI of the small bowel in Crohn’s disease
after enteroclysis with oral magnetic particles. Radi-
ologe 38:29–36
24. Mattrey RF, Trambert MA, Brown JJ et al (1994) Per-
flubron as an oral contrast agent for MR imaging:
results of a phase III clinical trial. Radiology
191:841–848
25. Rieber A, Aschoff A, Nussle K et al (2000) MRI in the
diagnosis of small bowel disease: use of positive and
negative oral contrast media in combination with
enteroclysis. Eur Radiol 10:1377–1382
26. Kivelitz D, Gehl HB, Heuck A et al (1999) Ferric
ammonium citrate as a positive bowel contrast agent
for MR imaging of the upper abdomen: safety and
diagnostic efficacy. Acta Radiol 40:429–435
27. Marcos HB, Semelka RC (2000) Evaluation of Crohn’s
disease using halffourier RARE and gadolinium-
enhanced SGE sequences: initial results. Magn Reson
Imaging 18:263–268
28. Low RN, Francis IR, Politoske D, Bennett M (2000)
Crohn’s disease evaluation: comparison of contrast-
enhanced MR imaging and single-phase helical CT
scanning. J Magn Reson Imaging 11:127–135
29. Shoenut JP, Semelka RC, Silverman R (1993) Magnetic
resonance imaging in inflammatory bowel disease. J
Clin Gastroenterol 17:73–78
30. Shoenut JP, Semelka RC, Magro CM (1994). Compari-
son of magnetic resonance imaging and endoscopy in
distinguishing the type and severity of inflammatory
bowel disease. J Clin Gastroenterol 19:31–35
31. Daldrup H, Shames DM, Wendland M et al (1998) Cor-
relation of dynamic contrast-enhanced MR imaging
with histologic tumor grade: comparison of macro-
molecular and small-molecular contrast media. AJR
171:
941–949
32. Best WR, Becktel JM, Singleton JW, Kern F (1976)
Development of a Crohn’s disease activity index:
National Cooperative Crohn’s Disease Study. Gas-
troenterology 70:439–444
33. Maccioni F, Viscido A, Broglia L et al (2000) Evalua-
tion of Crohn’s disease activity with magnetic reso-
nance imaging. Abdom Imaging 25:219–228
34. Horsthuis K, Lavini Mphil C, Stoker J (2005) MRI in
Crohn’s disease. J Magn Reson Imaging 22(1):1–12
35. Schunk K, Kern A, Oberholzer K et al (2000) Hydro-
MRI in Crohn’s disease: appraisal of disease activity.
Invest Radiol 35:431–437
36. Lomas DJ, Graves MJ (1999) Small bowel MRI using
water as a contrast medium. Br J Radiol 72:994–997
37. Prassopoulos P, PapanikolaouN, Grammatikakis J et
al (2001) MR Enteroclysis Imaging of Crohn’s Disease.
Radiographics 21:S161–S172
38. Furukawa A, Saotome T, Yamasaki M et al (2004)
Cross-sectional imaging in Crohn’s disease. Radi-
ographics 24(3):689–702
39. Koh DM, Miao Y, Chinn RJ et al (2001) MR imaging
evaluation of the activity of Crohn’s disease. AJR
177(6):1325–1332
SECTION II
Inflammatory Bowel Disease
Descriptive Epidemiology
Inflammatory bowel diseases (IBD) are a collection
of diseases affecting the bowel, the most common of
which are ulcerative colitis and Crohn’s disease.
Whereas UC is characterised by a continuous distri-
bution of mucosal/submucosal inflammation within
the colon, CD may result in focal areas of disease in
any part of the gastrointestinal tract from the mouth
to the anus; the inflammation is transmural and
almost inevitably progresses over time, often leading
to structuring or fistulising complications. Extra-
intestinal complications affecting eyes, skin and
joints occur in both illnesses. Although inflammato-
ry bowel disease is not common or highly fatal, it is
important to public health because its highest inci-
dence is early in life, its therapy involves major sur-
gery including a curative colectomy for ulcerative
colitis, and having the disease increases the risk of
developing colon cancer.
There are literally hundreds of articles describing
the incidence of ulcerative colitis and Crohn’s disease
in many regions of the world. In general, the highest
incidence rates and prevalence for both diseases have
been reported in northern Europe [1–8], the United
Kingdom [9–11], and North America [12–15], which
are the geographic regions that have been historically
associated with IBD. However, reports of increasing
incidence and prevalence from other areas of the
world such as southern or central Europe [16–18],
Asia [19–22], Africa [23], and Latin America [24]
underscore the fact that the occurrence of IBD is a
dynamic process. Incidence of UC, especially, is rising
in several areas previously thought to have low inci-
dence including Japan [21], South Korea [25], Singa-
pore [22], northern India [26] and Latin America [24].
In most of these areas, however, CD remains rare.
In North America, incidence rates range from 2.2
to 14.3 cases/100 000 person-years for UC and from
3.1 to 14.6 cases/100 000 person-years for CD. Preva-
lence ranges from 37 to 246 cases/100 000 persons for
UC and from 26 to 199 cases/100 000 persons for CD
[12–14].
The Multicenter European Collaborative Study on
Inflammatory Bowel Disease (EC-IBD) reported
blended incidence rates between 8.7 and 11.8
cases/100 000 person-years for UC and between 3.9
and
7.0 cases/100 000 person-years for CD [6]. The
EC-IBD quantified the north–south gradient of inci-
dence in Europe: the incidence rates for UC and for
CD were respectively 40 and 80% higher in northern
regions.
IBD:Epidemiology and Risk Factors
Gabriele Riegler,Annalisa de Leone
Fig. 1. UC incidence rates in Italy ([27]) Fig. 2. CD incidence rates in Italy ([27])
16 G. Riegler, A. de Leone
The last study from northern England [11] sug-
gested that the prevalence of IBD in 1995 was 243/100
000 persons for UC and 144/100 000 persons for CD.
Italy, until some years ago, was considered among
the countries with low incidence. In Italy, incidence
rates are of 5.2 cases/100 000 person-years for UC
and 2.3 cases/100 000 person-years for CD (Figs. 1, 2)
[27].
The northern European studies based on popula-
tion grounds have shown that there is no increase in
overall mortality in IBD [28]. Only in CD has there
been an increased mortality observed in the first few
years after diagnosis in young patients. In some stud-
ies, this was observed primarily in the females. The
Italian studies data confirm other European studies
[29–31].
In general, there is a slight female predominance
in Crohn’s disease, especially among women in late
adolescence and early adulthood, which suggests that
hormonal factors may play a role in disease expres-
sion. On the other hand, if there is a slight gender
predominance regarding UC, it rests with males [15].
For UC, different patterns of incidence were
observed for men and women aged 35 and over, with
Fig. 4. Female annual incidence for UC ([32])
Fig. 5. Male annual incidence for UC ([32]
Fig. 6. Ratio of males to females according to smoking
habits and age quartiles ([33])
Fig. 3. a Male and female incidence in different age groups
for UC. b Male and female incidence in different age groups
for CD ([6])
b
a
Соседние файлы в папке Библиотека им академика М.И. Перельмана