4. Oussalah A, Laurent V, Bruot O, et al. Diffusion-weighted magnetic resonance without bowel preparation for detecting colonic inflammation in inflammatory bowel disease. Gut 2010; 59: 1056–65.
5. Horsthuis K, Bipat S, Stokkers PCF, Stoker J. Magnetic resonance imaging for evaluation of disease activity in Crohn’s
disease: a systematic review. Eur Radiol 2009; 19: 1450–60.
6. Koh DM, Collins DJ. Diffusion-weighted MRI in the body: applications and challenges in oncology. AJR Am J Roentgenol 2007;188: 1622–35.
Commentary: diffusion-weighted magnetic
resonance imaging - a novel way to
assess disease activity in Crohn
’s
disease? Authors
’ reply
A. Buisson*
,†& V. Petitcolin
‡*Department of Gastroenterology, University Hospital Estaing of Clermont-Ferrand, Auvergne University, Clermont-Ferrand, France.
†Microbes, Intestine, Inflammation and Susceptibility of the Host,
UMR Inserm/Auvergne University U1071, USC-INRA 2018, Clermont-Ferrand University, Clermont-Ferrand, France.
‡Department of Radiology, University Hospital Estaing of
Clermont-Ferrand, Clermont-Ferrand, France. E-mail: a_buisson@hotmail.fr
doi:10.1111/apt.12277
We thank Lambie and Tolan for their comment on our
article.
1, 2As underscored by the authors, how to assess
Crohn’s disease (CD) activity or remission is a key point
in the era of biologics. To answer this question, the
emergence of new therapeutic goals, such as mucosal
healing or preventing digestive damage, have to be
con-sidered.
Although the CD Activity Index (CDAI) was the gold
standard to define clinical response or remission,
3achieving these new goals warrant other tools for
moni-toring the therapeutic ef
ficacy. In this context,
biomar-kers and magnetic resonance imaging (MRI) appear as
very promising non-invasive tools. Contrary to
Hors-thuis’ meta-analysis,
4the creators of the magnetic
reso-nance index of Activity (MaRIA) reported a very
high-diagnostic accuracy in differentiating active from inactive
segment
(
>0.8).
5This
difference
could
be
partly
explained by the heterogeneity in de
fining disease
activ-ity or remission.
Although the performances of conventional or
diffu-sion weighted MRI are probably lower for the detection
of mild lesions,
4we considered that it is not prejudicial
in monitoring therapeutic response. Is a patient with
persistent mild disease after treatment without ulceration
eligible for therapeutic optimisation? This is a key point
in the real-life setting. Though deep ulcers are correlated
with a more aggressive clinical course with an increased
rate of penetrating complications and surgery,
6the
natu-ral history of mild lesions remains unknown.
As we focused on terminal ileal involvement, the
choice of the most active segment as endpoint seemed to
us appropriate. Though the apparent diffusion coefficient
(ADC) measurement could be improved by using
nor-malised measurements, polyethylene glycol in small
vol-ume is, in our experience, well-tolerated and DWI-MRI
seems an objective, reproducible, non time-consuming
and accurate tool in the assessment of CD activity.
ACKNOWLEDGEMENT
The authors
’ declarations of personal and financial
inter-ests are unchanged from those in the original article.
2REFERENCES
1. Lambie H, Tolan D. Commentary: diffusion-weighted magnetic resonance imaging - a novel way to assess disease activity in Crohn’s disease? Aliment Pharmacol Ther 2013; 37: 833–4. 2. Buisson A, Joubert A, Montoriol P-F, et al. Diffusion-weighted
magnetic resonance imaging for detecting and assessing ileal inflammation in Crohn’s disease. Aliment Pharmacol Ther 2013; 37: 537–45.
3. Best WR, Becktel JM, Singleton JW, et al. Development of a Crohn’s disease activity index. National Cooperative Crohn’s Disease Study. Gastroenterology 1976;70: 439–44.
4. Horsthuis K, Bipat S, Stokkers PCF, et al. Magnetic resonance imaging for evaluation of disease activity in Crohn’s disease: a systematic review. Eur Radiol 2009;19: 1450–60.
5. Rimola J, Ordas I, Rodriguez S, et al. Magnetic resonance imaging for evaluation of Crohn’s disease: validation of parameters of severity and quantitative index of activity. Inflamm Bowel Dis 2011; 17: 1759–68.
6. Allez M, Lemann M, Bonnet J, et al. Long term outcome of patients with active Crohn’s disease exhibiting extensive and deep ulcerations at colonoscopy. Am J Gastroenterol 2002;97: 947–53.
834 Aliment Pharmacol Ther 2013; 37: 833-834
ª 2013 Blackwell Publishing Ltd