John Grammatikakis

Assessment of Crohn's disease activity in the small bowel with MR and conventional enteroclysis: preliminary results

Every single imaging finding that can be disclosed on conventional and MR enteroclysis was correlated with the Crohn’s disease activity index (CDAI). Nineteen consecutive patients with Crohn’s disease underwent colon endoscopy and both conventional and MR enteroclysis examinations. Seventeen MR imaging findings and seven conventional enteroclysis findings were ranked on a four-point grading scale and correlated with CDAI, with a value of 150 considered as the threshold for disease activity. Six patients had active disease in the colon according to colon endoscopy. In the remaining 13 patients, the presence of deep ulcers (P=0.002), small bowel wall thickening (P=0.022) and gadolinium enhancement of mesenteric lymph nodes (P=0.014) identified on MR enteroclysis images were strongly correlated to disease activity. The product of deep ulcers and enhancement of lymph node ranks identified on MR enteroclysis were the optimum combination for discriminating active from non-active disease (F-test: 55.95, P<0.001). Additionally, the ranking of deep ulcers on conventional enteroclysis provided statistically significant differences between active and non-active patients (F-test: 14.12, P=0.004). Abnormalities strongly suggestive of active Crohn’s disease can be disclosed on MR enteroclysis examinations and may provide pictorial information for local inflammatory activity.

MR enteroclysis: technical considerations and clinical applications.

Abstract. Magnetic resonance enteroclysis (MRE) is an emerging technique for the evaluation of small bowel abnormalities. Adequate luminal distention, achieved by the administration of iso-osmotic water solution through a nasojejunal catheter, in combination with ultrafast sequences, such as single-shot turbo spin echo, true fast imaging with steady precession, half-Fourier acquired single-shot turbo spin echo, and 3D fast low-angle shot, results in excellent anatomic demonstration of the small bowel. Magnetic resonance fluoroscopy can be performed during MRE examination and might be useful in studying low-grade stenosis or motility-related disorders. Magnetic resonance enteroclysis is very promising in detecting the number and extent of involved small bowel segments in patients with Crohn’s disease, and in disclosing lumen narrowing and extramural manifestations and complications of the disease. Initial experience shows that MRE is very efficient in the diagnosis of small bowel tumors and can be used in the evaluation of small bowel obstruction.

Imaging of small intestinal Crohn’s disease: comparison between MR enteroclysis and conventional enteroclysis

The purpose of this study was to compare MR enteroclysis (MRE) with conventional enteroclysis (CE) in patients with small intestinal Crohn’s disease. Fifty-two consecutive patients with known or suspected Crohn’s disease underwent MR and conventional enteroclysis, which was considered the gold standard. Eleven imaging features, classified in three groups, mucosal, transmural and extraintestinal, were subjectively evaluated by two experienced radiologists. MRE and CE were in full agreement in revealing, localizing and estimating the length of all involved segments of the small bowel. The sensitivity of MRE for the detection of superficial ulcers, fold distortion and fold thickening was 40, 30 and 62.5%, respectively. The sensitivity of MRE for the detection of deep ulcers, cobble-stoning pattern, stenosis and prestenostic dilatation was 89.5, 92.3, 100 and 100%, respectively. Additional findings demonstrated on MRE images included fibrofatty proliferation in 15 cases and mesenteric lymphadenopathy in 19 cases. MRE strongly correlates with CE in the detection of individual lesions expressing small intestinal Crohn’s disease. It provides additional information from the mesenteries; however, its capability to detect subtle lesions is still inferior to conventional enteroclysis.

MR enteroclysis protocol optimization: comparison between 3D FLASH with fat saturation after intravenous gadolinium injection and true FISP sequences

Abstract. The aim of this study was to introduce the true fast imaging with steady-state precession (FISP) sequence for MR enteroclysis and compare it with the already used T1-weighted fast low-angle shot (FLASH) sequence. Twenty-one patients underwent both MR and conventional enteroclysis. The MR enteroclysis examination was performed after administration of an iso-osmotic water solution through a nasojejunal catheter and the following sequences were included: (a) true FISP; and (b) 3D FLASH with fat saturation after intravenous injection of 20xa0mg Buscopan or 1xa0mg glucagon and 0.1xa0mmol/kg gadolinium chelates. The true FISP sequence provided images with significantly fewer motion artifacts, whereas 3D FLASH was less sensitive to susceptibility and chemical shift artifacts. The homogeneity of endoluminal opacification, wall conspicuity, and distention of the small bowel were very good to excellent and the two sequences presented no statistically significant differences here. True FISP provided significantly better overall image quality than did 3D FLASH. The true FISP sequence can provide good anatomic demonstration of the small bowel on T2-like images and could be combined with T1-weighted FLASH images for an integrated protocol of MR enteroclysis.

MR imaging of the small bowel with a true-FISP sequence after enteroclysis with water solution.

Gourtsoyiannis N, Papanikolaou N, Grammatikakis J, et al. MR imaging of the small bowel with a true-FISP sequence after enteroclysis with water solution. Invest Radiol 2000;35:707–711. RATIONALE AND OBJECTIVES.To evaluate a novel MR enteroclysis technique for small-bowel imaging. METHODS.Twenty-one patients with suspected small-bowel disease underwent both MR and conventional enteroclysis. MR enteroclysis was performed by injecting an iso-osmotic water solution through a nasojejunal catheter with a flow rate of 80 to 150 mL/min. A maximum of 2 L of water solution was administered. A dynamic heavily T2-weighted single-shot turbo spin-echo sequence was applied in coronal orientation to monitor the bowel filling and adequate distention. Twelve 4-mm-thick slices were acquired by using a true fast imaging with steady-state precession (true-FISP) sequence during an 18-second breath-hold interval. Small-bowel distention, wall conspicuity, homogeneity of opacification, and the presence of artifacts were subjectively evaluated by two reviewers using five-point scales. RESULTS.Chemical shift artifacts were low and ghost artifacts were absent. Susceptibility artifacts were more prominent in the ileum; motion artifacts were low in the jejunum, ileum, and ileocecal area. Homogeneity of opacification was very good in the jejunum, good to very good in the ileum, and good in the ileocecal area. Distention was very good to excellent in the jejunum and ileum and very good in the ileocecal area. Wall conspicuity was very good to excellent in the jejunum and ileum. CONCLUSIONS.MR enteroclysis with the true-FISP sequence produced high-quality images of the small bowel. Further clinical studies are required to determine the clinical efficacy of the new technique compared with conventional enteroclysis.

Radiogenic risks from hysterosalpingography

The aim of this study was to determine ovarian dose, effective dose and associated radiogenic risks from hysterosalpingography (HSG), and to provide data for the estimation of radiogenic risks related to HSG studies performed in any laboratory. The fluoroscopy time, number of radiographs taken and entrance surface dose were measured in a series of 78 consecutive patients undergoing HSG as part of their infertility work-up. Organ-dose values per radiograph and per minute of fluoroscopy were separately determined using an anthropomorphic phantom and thermoluminescence dosimetry. The radiogenic risk for deleterious effects on a possible future embryo and the radiogenic risk for cancer induction on the patient undergoing HSG were estimated. The average HSG procedure in our laboratory involves a mean fluoroscopic time of 0.3xa0min and a mean number of radiographs of 3.2. The dose to female gonads from an average HSG procedure was 2.7xa0mGy and the patient effective dose was 1.2xa0mSv. The risk for radiogenic anomalies in a future embryo of the woman undergoing an average HSG procedure and the risk for radiogenic fatal cancer induction in the exposed woman were estimated to be less than 10–3 of the correspondent nominal risks. Radiation risks from a typical HSG are low, but they may be elevated if fluoroscopic and/or radiographic exposures are prolonged for any reason. Present data allow the estimation of radiogenic risks associated with HSG procedures performed in other laboratories with use of different equipment, screening time and number of radiographs taken.

Crohn's disease lymphadenopathy: MR imaging findings

PURPOSEnTo assess mesenteric lymph nodes in patients with different Crohns disease subtypes identified on MR Enteroclysis.nnnMATERIALS AND METHODSnThirty-four patients, categorized into three different Crohns disease subgroups, underwent MR Enteroclysis. A high resolution coronal true FISP sequence with fat saturation was applied to assess mesenteric lymph node anatomic distribution, size and shape. Their enhancement ratio (ER) was calculated by dividing signal intensity of each node to signal intensity of nearby vessel on T1 weighted FLASH images, acquired 75 s after intravenous administration of gadolinium. A one-way analysis of variance statistical test was applied to investigate any significant differences regarding mean ER among different disease subgroups.nnnRESULTSnTwo hundred and eighty-three mesenteric lymph nodes were assessed, 231 in patients with active inflammatory (AI) disease, 36 in patients with fibrostenotic (FS) and 16 in patients with fistulizing/perforating (FP) disease. Maximum and minimum diameters were 3.2 and 0.3 cm, respectively. 75% of the lymph nodes presented with an oval shape. The majority were identified as being ileocolic (34%) and paracolic (31%). AI subgroup lymph nodes presented with the highest mean ER (0.783+/-0.17) followed by FP (0.706+/-0.1) and FS subgroup (0.652+/-0.17) lymph nodes. The differences in mean values of ER of mesenteric lymph nodes between AI and FS subtypes were statistically significant (p<0.0001), while mean ER between nodes of FP and the other two subtypes did not present statistically significant differences.nnnCONCLUSIONnER of mesenteric lymph nodes identified on MR Enteroclysis may vary across different subtypes of Crohns disease. Such differences may be valuable in clinical practice.

Optimization of a contrast medium suitable for conventional enteroclysis, MR enteroclysis, and virtual MR enteroscopy

AbstractBackground: The purpose of the current study was to optimize a gadolinium-barium sulfate solution suitable for performing conventional and MR enteroclysis examinations in the same session.nMethods: Eighteen vials of 20% barium sulfate and various gadolinium concentrations (lower 0 ml/lt, higher 45 ml/lt) were prepared and placed in the magnet. The imaging protocol was consisted of the following sequences: true FISP, HASTE with fat saturation and 3d FLASH with fat saturation in various flip angles. Ten patients underwent conventional enteroclysis with 1.2 lt of 20% barium sulfate enema and 18 ml of gadolinium. MR enteroclysis was performed afterwards using true FISP, fat suppressed 3d FLASH and fat suppressed HASTE sequences.nResults: The lowest gadolinium concentration in the barium sulfate solution generating low intraluminal signal on HASTE and high intraluminal signal on true FISP and 3d FLASH sequences was 15 ml/lt. The presence of gadolinium did not influence the lumen opacification in conventional enteroclysis examination. In all patients the proposed contrast medium acted as positive in 3d FLASH (T1w), true FISP (T2/T1 w) and as a negative in HASTE (T2w). Bowel wall conspicuity, lumen opacification and distention were ranked as very good to excellent on MR enteroclysis images while artifacts level did not downgraded the overall image quality. High quality virtual MR endoluminal views of the small bowel, based on 3d FLASH images, were obtained in all cases.nConclusion: A 20% barium sulfate enema with 15 ml/lt gadolinium is appropriate for conventional and MR enteroclysis examinations.

Accidental embryo irradiation during barium enema examinations. An estimation of absorbed dose.

RATIONALE AND OBJECTIVESnTo investigate the possibility of an embryo to receive a dose of more than 10 cGy, the threshold of malformations induction in embryos reported by the International Commission on Radiological Protection, during barium enema examinations.nnnMETHODSnThermoluminescent dosimeters were placed in a phantom to calculate the depth-to-skin conversion coefficient needed for dose estimation at the average embryo depth in patients. Barium enema examinations were performed in 20 women of childbearing age with diagnostic problems demanding longer fluoroscopy times. Doses at 6 cm, the average embryo depth, were determined by measurements at the patients skin followed by dose calculation at the site of interest.nnnRESULTSnThe range of doses estimated at embryo depth for patients was 1.9 to 8.1 cGy. The dose always exceeded 5 cGy when fluoroscopy time was longer than 7 minutes.nnnCONCLUSIONnThe dose at the embryo depth never exceeded 10 cGy. This study indicates that fluoroscopy time should not exceed 7 minutes in childbearing-age female patients undergoing barium enema examinations.

MR colonography with fecal tagging: comparison between 2D turbo FLASH and 3D FLASH sequences

Abstract.The objective of this study was to compare inversion recovery turbo 2D fast low-angle shot (FLASH) and 3D FLASH sequences for fecal-tagged MR colonography studies. Fifteen consecutive patients with indications for colonoscopy underwent MR colonography with fecal tagging. An inversion recovery turbo-FLASH sequence was applied and compared in terms of artifacts presence, efficiency for masking residual stool, and colonic wall conspicuity with a fat-saturated 3D FLASH sequence. Both sequences were acquired following administration of paramagnetic contrast agent. Contrast-to-noise ratio and relative contrast between colonic wall and lumen were calculated and compared for both sequences. Turbo 2D FLASH provided fewer artifacts, higher efficiency for masking the residual stool, and colonic wall conspicuity equivalent to 3D FLASH. An inversion time of 10xa0ms provided homogeneously low signal intensity of the colonic lumen. Contrast to noise between colonic wall and lumen was significantly higher in the 3D FLASH images, whereas differences in relative contrast were not statistically significant. An optimized inversion-recovery 2D turbo-FLASH sequence provides better fecal tagging results and should be added to the 3D FLASH sequence when designing dark-lumen MR colonography examination protocols.