T2-weighted half-Fourier Acquisition Single-shot Turbo Research Articles

Quantification of Visceral Fat at the L5 Vertebral Body Level in Patients with Crohn's Disease Using T2-Weighted MRI.

The umbilical or L3 vertebral body level is often used for body fat quantification using computed tomography. To explore the feasibility of using clinically acquired pelvic magnetic resonance imaging (MRI) for visceral fat measurement, we examined the correlation of visceral fat parameters at the umbilical and L5 vertebral body levels. We retrospectively analyzed T2-weighted half-Fourier acquisition single-shot turbo spin echo (HASTE) MR axial images from Crohn's disease patients who underwent MRI enterography of the abdomen and pelvis over a three-year period. We determined the area/volume of subcutaneous and visceral fat from the umbilical and L5 levels and calculated the visceral fat ratio (VFR = visceral fat/subcutaneous fat) and visceral fat index (VFI = visceral fat/total fat). Statistical analyses involved correlation analysis between both levels, inter-rater analysis between two investigators, and inter-platform analysis between two image-analysis platforms. Correlational analysis of 32 patients yielded significant associations for VFI (r = 0.85; p < 0.0001) and VFR (r = 0.74; p < 0.0001). Intraclass coefficients for VFI and VFR were 0.846 and 0.875 (good agreement) between investigators and 0.831 and 0.728 (good and moderate agreement) between platforms. Our study suggests that the L5 level on clinically acquired pelvic MRIs may serve as a reference point for visceral fat quantification.

Differentiating gallbladder cancer from polyps using non-enhanced magnetic resonance imaging.

This retrospective cohort study assessed the efficiency of non-enhanced magnetic resonance imaging (MRI) for differentiating gallbladder cancer (GBC) from gallbladder polyps (GBPs) measuring ≥ 10 mm. Patients diagnosed with GBCs or GBPs ≥ 10 mm and GBC ≤ T2 stage were eligible for inclusion. Two independent blinded readers assessed the continuity of the mucosal and muscular layers (CMML; present or absent) and normalised signal intensity ratio (NIR) on the apparent diffusion coefficient map (NIR-ADC), T1-weighted image (NIR-T1WI), and T2-weighted half-Fourier acquisition single-shot turbo spin-echo image. Univariate and multivariate logistic regression analyses and interobserver agreement analyses were performed to detect predictive variables differentiating GBCs from GBPs. Receiver operating characteristic (ROC) analysis was performed to evaluate diagnostic performance. A reproducibility test was performed to verify the predictive variables. Multivariate analysis showed significant differences in CMML, NIR-ADC, and NIR-T1WI (p < 0.001). The positive predictive value (PPV) and specificity of the absence of CMML were approximately 100%. The CMML showed the best specificity, accuracy, and PPV in the reproducibility study. The sensitivity of CMML alone was approximately 50%, whereas it increased to approximately 70% when combined with NIR-ADC. The diagnostic performance of the combination, including sensitivity, was almost like that of tumour size. The combined tumour size and CMML assessment showed higher diagnostic performance than tumour size alone. The absence of CMML and NIR-ADC ≤ 1.86 helped in differentiating GBCs from GBPs. Evaluation of the absence of CMML and measurement of tumour size could better aid in determining between the two than measurement of tumour size alone.

Diagnostic performance of multiparametric magnetic resonance imaging in the differentiation of clear cell renal cell cancer.

This study aimed to evaluate the diagnostic performance of multiparametric magnetic resonance imaging (mpMRI) in the differentiation of renal cell carcinoma (RCC) subtypes. This is a retrospective diagnostic performance study, in which the diagnostic performances of mpMRI features were evaluated to differentiate clear cell RCC (ccRCC) from non-clear cell RCC (non-ccRCC). Adult patients who were evaluated using a 3-Tesla dynamic contrast-enhanced mpMRI before undergoing partial or radical nephrectomy for possible malignant renal tumors were included in the study. Signal intensity change percentages (SICP) between contrast-enhanced phases and pre-administration period for both the tumor and normal renal cortex, and tumor-to-cortex enhancement index (TCEI); tumor apparent diffusion coefficient (ADC) values; tumor-to-cortex ADC ratio; and a scale which was developed according to the tumor signal intensities on the axial fat-suppressed T2-weighted Half-Fourier Acquisition Single-shot Turbo spin Echo (HASTE) images were used in ROC analysis to estimate the presence of ccRCC in the patients. The reference test positivity was the histopathologic examination of the surgical specimens. Ninety-eight tumors from 91 patients were included in the study, and 59 of them were ccRCC, 29 were pRCC, and 10 were chRCC. The mpMRI features that had the three highest sensitivity rates were excretory phase SICP, T2-weighted HASTE scale score, and corticomedullary phase TCEI (93.2%, 91.5%, and 86.4%, respectively). However, those with the three highest specificity rates were nephrographic phase TCEI, excretory phase TCEI, and tumor ADC value (94.9%, 94.9%, and 89.7%, respectively). Several parameters on mpMRI showed an acceptable performance to differentiate ccRCC from non-ccRCC.

Rapid Magnetic Resonance Imaging of the Spine in Neonates with Spinal Dysraphism

The use of nonsedated T2-weighted Half-Fourier Acquisition Single-shot Turbo spin Echo magnetic resonance imaging (MRI) sequences in screening for spinal cord syrinx in neonates with spinal dysraphism has not been reported in the literature. We sought to review our experience using T2-weighted Half-Fourier Acquisition Single-shot Turbo spin Echo imaging of the spine (i.e., rapid spine MRI) in nonsedated neonates for detecting spinal cord syrinx in neonates with spinal dysraphism. We performed a retrospective search of our radiology database for neonates with spinal dysraphism who had rapid spine MRI between May 2017 and February 2020. The images were reviewed in conjunction with clinical findings and standard spine imaging, when available. Thirty studies (in 29 neonates) fulfilled our inclusion criteria. Of the 26 neonates with myelomeningocele, 5 of them (19%) had spinal cord syrinx identified on neonatal rapid spine MRI. An additional 2 patients developed syrinx by 2 years of age. Potential pitfalls identified in interpreting rapid spine MRI include motion artifacts and distinguishing a severe holocord syrinx from a truncated spinal cord. Rapid spine MRI acquired without sedation or anesthesia may be used as a screening technique to detect spinal cord syrinx in neonates with spinal dysraphism.

Use of fast-sequence spine MRI in pediatric patients.

The immediate and long-term risk of anesthesia in the pediatric population is controversial. Traditional spine MRI protocols require the patient to remain still during the examination, and in young children this frequently results in the need for sedation administration. The authors' goal was to develop an abbreviated spine MRI protocol to reduce sedation administration in young patients undergoing spine MRI. After IRB approval, the medical records of all pediatric patients who underwent a fast spine MRI protocol between 2017 and 2019 were reviewed. The protocol consisted of T2-weighted half-Fourier acquisition single-shot turbo spin echo, T1-weighted turbo spin echo, and T2-weighted STIR sequences acquired in the sagittal plane. The total acquisition time was 2 minutes with no single sequence acquisition longer than 60 seconds. Interpretability of the scans was assessed in accordance with the radiology report in conjunction with the neurosurgeon's clinical notes. A total of 47 fast spine MRI sessions were performed in 45 patients. The median age at the time of the MRI was 2.4 years (25th-75th quartile, 1.1-4.3 years; range 0.16-18.58 years). The most common indication for imaging was to rule out or follow a known syrinx (n = 30), followed by the need to rule out or follow known spinal dysraphism (n = 22). There were no uninterpretable or unusable scans. Eight of 47 scans were noted to have moderate motion artifact limitations with respect to the quality of the scan. Seven patients underwent a subsequent MRI with a sedated standard spine protocol within 1 year from the fast scan, which confirmed the findings on the fast MRI protocol with no new findings identified. The authors report the first pediatric series of a fast spine MRI protocol for use in young patients. The protocol does not require sedation and is able to identify and monitor syrinx, spinal dysraphism, and potentially other intraspinal anomalies.

Misleading findings of liver-specific MR contrast agent for radiological diagnosis of cysto-biliary communication in hydatid cysts.

To investigate the effectiveness of gadoxetic acid-enhanced magnetic resonance cholangiopancreatography (CE-MRCP) and T2-weighted half-Fourier acquisition single-shot turbo spin-echo (T2W HASTE) sequences for diagnosis of cysto-biliary communication in hydatid cysts compared to surgical results. Preoperative abdominal magnetic resonance imaging examinations of patients who underwent surgery for hepatic hydatid cysts were reviewed by two radiologists retrospectively. A total of 45 patients with hydatid cysts were included. Of 45, 27 also had CE-MRCPs. T2W HASTE sequences and CE-MRCPs were investigated separately for cysto-biliary communication. The relationship between radiological and surgical results was analyzed. The interobserver agreement was evaluated. Of 45 hydatid cysts, there were surgically proven 21 cysts without biliary communications and 24 cysts with biliary communications. All cysts with biliary communications were shown on T2W HASTE sequences. There was no leakage of gadoxetic acid into these cysts (n = 24). Sensitivity, specificity, negative predictive value, positive predictive value (PPV), and accuracy of diagnosis of cyst with biliary communication on T2W HASTE sequences was 100%, 63.64%, 100%, 66.67%, and 78.95%, respectively. Specificity (77.78%), PPV (87.50%), and accuracy (91.30%) were increased in ≥ 10cm cysts. There was almost perfect interobserver agreement (K = 0.81-1.00). Leakage of gadoxetic acid inside the cyst indicates biliary communication. However, the lack of leakage does not rule out cysto-biliary communication. When biliary communication is clearly shown on T2W HASTE sequences, it should be reported as cysto-biliary communication even if there is no leakage of gadoxetic acid into the cyst on CE-MRCP.

Swallowing MRI\u2014a reliable method for the evaluation of the postoperative gastroesophageal situs after Nissen fundoplication

PurposeTo evaluate the diagnostic performance of swallowing MRI of the gastroesophageal junction (GEJ) in the postoperative care of patients after laparoscopic antireflux surgery (LARS)Material and methodsIn this institutional review board-approved prospective study, 79 symptomatic patients (mean age, 52.3 years; range, 26–80 years) were evaluated after laparoscopic Nissen fundoplication. MRI findings were correlated with revision surgery, endoscopy, and high-resolution manometry (HRM) as standard of reference. MRI was performed on a 3.0-T unit using T2-weighted half-Fourier acquisition single-shot turbo spin echo (HASTE) sequences for anatomical assessment of the GEJ followed by dynamic MR swallowing (fast low-angle shot sequences). Four independent readers (two radiologists, two surgeons) rated 83 MR scans according to defined criteria, such as wrap disruption, slipping, recurrent hiatal hernia, and esophageal motility disorder.ResultsWrap disruption was correctly diagnosed concordantly with the standard of reference in 87.8%, slipping in 81.5%, and recurrent hiatal hernia in 84.9% of the cases. For esophageal motility disorder, MRI interpretation was consistent with manometry in 66.2% of the subjects. Interobserver analysis showed substantial agreement for recurrent hiatal hernia (k = 0.703), moderate agreement for wrap disruption (k = 0.585), and fair agreement for motility disorder and slipping (k = 0.234 and k = 0.200, respectively).ConclusionMR swallowing readily depicts the major failure mechanisms of LARS and has good reliability even in non-experienced readers.Key Points• MR swallowing accurately readily depicts the major failure mechanisms of laparoscopic antireflux surgery and has good reliability even in non-experienced readers.• It should be included in the preoperative workup for revision surgery after fundoplication.• It will be of great benefit to surgeons in considering and planning a reoperation.

T2-weighted four dimensional magnetic resonance imaging with result-driven phase sorting.

T2-weighted MRI provides excellent tumor-to-tissue contrast for target volume delineation in radiation therapy treatment planning. This study aims at developing a novel T2-weighted retrospective four dimensional magnetic resonance imaging (4D-MRI) phase sorting technique for imaging organ/tumor respiratory motion. A 2D fast T2-weighted half-Fourier acquisition single-shot turbo spin-echo MR sequence was used for image acquisition of 4D-MRI, with a frame rate of 2-3 frames/s. Respiratory motion was measured using an external breathing monitoring device. A phase sorting method was developed to sort the images by their corresponding respiratory phases. Besides, a result-driven strategy was applied to effectively utilize redundant images in the case when multiple images were allocated to a bin. This strategy, selecting the image with minimal amplitude error, will generate the most representative 4D-MRI. Since we are using a different image acquisition mode for 4D imaging (the sequential image acquisition scheme) with the conventionally used cine or helical image acquisition scheme, the 4D dataset sufficient condition was not obviously and directly predictable. An important challenge of the proposed technique was to determine the number of repeated scans (NR) required to obtain sufficient phase information at each slice position. To tackle this challenge, the authors first conducted computer simulations using real-time position management respiratory signals of the 29 cancer patients under an IRB-approved retrospective study to derive the relationships between NR and the following factors: number of slices (NS), number of 4D-MRI respiratory bins (NB), and starting phase at image acquisition (P0). To validate the authors' technique, 4D-MRI acquisition and reconstruction were simulated on a 4D digital extended cardiac-torso (XCAT) human phantom using simulation derived parameters. Twelve healthy volunteers were involved in an IRB-approved study to investigate the feasibility of this technique. 4D data acquisition completeness (Cp) increases as NR increases in an inverse-exponential fashion (Cp = 100 - 99 × exp(-0.18 × NR), when NB = 6, fitted using 29 patients' data). The NR required for 4D-MRI reconstruction (defined as achieving 95% completeness, Cp = 95%, NR = NR,95) is proportional to NB (NR,95 ∼ 2.86 × NB, r = 1.0), but independent of NS and P0. Simulated XCAT 4D-MRI showed a clear pattern of respiratory motion. Tumor motion trajectories measured on 4D-MRI were comparable to the average input signal, with a mean relative amplitude error of 2.7% ± 2.9%. Reconstructed 4D-MRI for healthy volunteers illustrated clear respiratory motion on three orthogonal planes, with minimal image artifacts. The artifacts were presumably caused by breathing irregularity and incompleteness of data acquisition (95% acquired only). The mean relative amplitude error between critical structure trajectory and average breathing curve for 12 healthy volunteers is 2.5 ± 0.3 mm in superior-inferior direction. A novel T2-weighted retrospective phase sorting 4D-MRI technique has been developed and successfully applied on digital phantom and healthy volunteers.

Biochemical Markers and MR Imaging Findings as Predictors of Crohn Disease Activity in Patients Scanned by Contrast-enhanced MR Enterography

To define the best independent predictors for active inflammation in patients with Crohn disease (CD) examined by contrast-enhanced magnetic resonance (MR) enterography. Ninety-one patients (47 men and 44 women; aged 39.58 ± 17.1 years) with a diagnosis of CD; CD activity index (CDAI) ≥ 150 (n = 19 patients) or <150 (n = 72) underwent MR enterography including T2-weighted half-Fourier acquisition single-shot turbo spin-echo, T2-weighted spectral fat presaturation with inversion recovery, T1-weighted balanced steady-state free precession, and T1-weighted breath-hold resolution isotropic high volume three-dimensional MR imaging sequences before and after administration of gadobenate dimeglumine during arterial (30 seconds), portal venous (70 seconds), and delayed phase (3 and 5 minutes from contrast injection). Two readers analyzed the MR images in consensus. Reference standard was the Crohn's Disease Endoscopic Index of Severity (CDEIS) with deep mucosal biopsy or the histologic analysis of the surgical specimen in those patients (n = 30) who underwent elective small-bowel resection. Univariate and multivariate logistic regression analyses were performed to assess CDAI, biochemical markers (C-reactive protein and fecal calprotectin levels) and MR imaging findings as potential predictors of inflammatory CD activity. Patients revealed prevalently active (n = 47 patients) or quiescent CD with mural fibrosis (n = 44 patients). The bowel wall T2 hyperintensity (odds ratio [OR], 9.20; 95% confidence interval [CI], 2.71-31.19) and total length of disease (OR, 1.29; 95% CI, 1.11-1.49) were found as the best independent predictors of active CD. CDAI, C-reactive protein, and fecal calprotectin were not found independent predictors of active CD. The bowel wall T2 hyperintensity and the length of the involved bowel tract were predictors of active inflammation in patients with CD examined by contrast-enhanced MR enterography.

MRI patterns of Nissen fundoplication: normal appearance and mechanisms of failure

The purpose of the study was to assess the role of MR fluoroscopy in the evaluation of post-surgical conditions of Nissen fundoplication due to gastro-oesophageal reflux disease (GERD). A total of 29 patients (21 patients with recurrent/persistent symptoms and eight asymptomatic patients as the control group) underwent MRI of the oesophagus and gastro-oesophageal junction (GEJ) at 1.5 T. Bolus transit of a buttermilk-spiked gadolinium mixture was evaluated with T2-weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) and dynamic gradient echo sequences (B-FFE) in three planes. The results of MRI were compared with intraoperative findings, or, if the patients were treated conservatively, with endoscopy, manometry, pH-metry and barium swallow. MRI was able to determine the position of fundoplication wrap in 27/29 cases (93% overall accuracy) and to correctly identify 4/6 malpositions (67%), as well as all four wrap disruptions. All five stenoses in the GEJ were identified and could be confirmed intraoperatively or during dilatation. MRI correctly visualized three cases with motility disorders, which were manometrically confirmed as secondary achalasia. Three patients showed signs of recurrent reflux without anatomical failure. MRI is a promising diagnostic method to evaluate morphologic integrity of Nissen fundoplication and functional disorders after surgery. MRI offers simultaneous morphological and functional imaging in one diagnostic method. MR fluoroscopy offers the possibility to identify the wrap position. MRI enables a non-invasive diagnosis, providing detailed information for the surgeon.

Fast-sequence MRI studies for surveillance imaging in pediatric hydrocephalus

Surveillance imaging of the cerebral ventricles can be valuable in following up children with shunt-treated hydrocephalus. There also, however, has been recent increased awareness and concern over the potential risk associated with imaging-related radiation exposure in children. Magnetic resonance imaging represents an imaging alternative that does not use ionizing radiation; however, its practical utility has been limited due to the near-uniform requirement for sedation or general anesthesia in children. Magnetic resonance imaging without sedation is often futile because of the movement artifact produced by the nonsedated pediatric patient. Some studies have demonstrated the feasibility of using fast-sequence MRI (fsMRI), but the reported experiences are limited. The authors have incorporated fsMRI into their routine shunt surveillance imaging paradigms and report here a 5-year experience with this modality. The authors initially started using fsMRI for routine surveillance in a single clinic in 2008 and have gradually increased their institutional utilization of this modality as experience has accumulated and protocols have been refined. Imaging sequences obtained for each child include an axial T2-weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE), coronal T2-weighted HASTE, and sagittal T2-weighted HASTE images. The authors conducted a retrospective chart and imaging review. They rated each fsMR image according to 5 visibility parameters: 1) ventricle size, 2) ventricle configuration, 3) presence or absence of transependymal flow, 4) presence or absence of motion artifact, and 5) visualization of the ventricular catheter. Each parameter was graded as 1 (present) or 0 (absent). Thus, the maximum value assigned to each scan could be 5 and the minimum value assigned to each scan could be 0. Interrater reliability between pairs of observers was calculated using the Kendall's tau-b and intraclass coefficients. Two hundred patients underwent fsMRI. No child required sedation. The average duration of examinations was approximately 3.37 minutes, and mean age of the patients was 5.7 years. Clinically useful images were attained in all cases. Overall quality of the fsMRI studies based on the 5 different visibility parameters showed that 169 images (84.5%) included 4 or 5 parameters (score ≥ 4) and had statistically significant excellent quality. The Kendall's tau-b for the overall fsMRI ratings was 0.82 (p = 0.002) and the intraclass coefficient was 0.87 (p < 0.0001). In the present cohort of 200 patients, fsMRI studies were shown to have an excellent overall quality and a statistically significant high degree of interrater reliability. Consequently, the authors propose that fsMRI is a sufficiently effective modality that eliminates the need for sedation and the use of ionizing radiation and that it should supplant CT for routine surveillance imaging in hydrocephalic patients.

Magnetic Resonance Imaging Analysis of Rotational Alignment in Patients With Patellar Dislocations

Background: The role of anatomic risk factors in patellofemoral instability is not yet fully understood, as they have been observed in patients either alone or in combination and in different degrees of severity. Purpose: To prospectively analyze rotational limb alignment in patients with patellofemoral instability and in controls using magnetic resonance imaging (MRI). Study Design: Cross-sectional study; Level of evidence, 3. Methods: Thirty patients (mean age, 22.9 y; range, 12-41 y) with a history of patellar dislocation and 30 age- and sex-matched controls (mean age, 25.2 y; range, 16-37 y) were investigated. The patients underwent MRI of the leg at 1.5 T using a peripheral angiography coil and a T2-weighted half-Fourier acquisition single-shot turbo spin echo (HASTE) sequence for measuring femoral antetorsion, tibial torsion, knee rotation, and mechanical axis deviation (MAD). The mean values of these parameters were compared between patients and controls. In addition, the patients underwent an assessment to determine the influence of rotational limb alignment on lateral trochlear inclination, trochlear facet asymmetry, trochlear depth, Insall-Salvati index, and tibial tuberosity–trochlear groove distance. Results: Patients had 1.56-fold higher mean femoral antetorsion (20.3° ± 10.4° vs 13.0° ± 8.4°; P < .01) and 1.6-fold higher knee rotation (9.4° ± 5.0° vs 5.7° ± 4.3°; P < .01) compared with controls. Moreover, patients had 2.9 times higher MAD (0.81 ± 0.75 mm vs −0.28 ± 0.87 mm; P < .01). Differences in tibial torsion were not significant. Also, there were no significant correlations between parameters of rotational alignment and standard anatomic risk factors. Conclusion: Our results suggest that some patients with nontraumatic patellar instability have greater internal femoral rotation, greater knee rotation, and a tendency for genu valgum compared with healthy controls. Rotational malalignment may be a primary risk factor in patellar dislocation that has so far been underestimated.

Role of diffusion weighted magnetic resonance imaging (DW MRI) in classification of liver hydatid cysts and differentiation of simple cysts and abscesses from hydatid cysts

The purpose of this study is to identify the role of diffusion-weighted magnetic resonance imaging (DW-MRI) in the classification of liver hydatid cysts (HCs) and their differentiation from simple cysts and liver abscesses. Twenty-two patients that were sent to our department with preliminary diagnoses of HCs or abscess were included in the study. Thirty lesions were evaluated. MRI included T1-weighted fast gradient echo, T2-weighted half-Fourier acquisition single-shot turbo spin echo, and DW single-shot echo planar pulse sequencing (b, 0, 50, and 1000 s/mm²). The apparent diffusion coefficient (ADC) values (mm²/s) of the HCs, abscesses, and simple cysts were calculated. No statistically significant difference was found between the ADC values of type 1 and 3 (P > 0.05) HCs and of simple cysts and type 1 HCs (P > 0.05). The ADC values of abscesses were significantly lower than those of type 1 and type 3 HCs, and simple cysts. No statistically significant difference was found between the ADC values of abscesses and type 4 HCs (P > 0.05). Type 4 lesions exhibited significantly lower ADC values in comparison to type 1 and 3 HCs. DW-MRI helps differentiate type 4 lesions from other cysts and can distinguish abscesses from hydatid cysts other than type 4 as well as from simple cysts. Type 1 HCs cannot be differentiated from simple cysts using ADC values alone, and type 4 lesions are indistinguishable from abscesses.

Congenital anomalies and variations of the bile and pancreatic ducts: magnetic resonance cholangiopancreatography findings, epidemiology and clinical significance

The objective of this paper is to document the magnetic resonance cholangiopancreatography (MRCP) findings and the epidemiology of congenital anomalies and variations of the bile and pancreatic ducts and to discuss their clinical significance. Three-hundred and fifty patients of both sexes (150 females, 200 males, age range 0-76 years, average age 38 years) underwent MRCP for clinically suspected lithiasic, neoplastic or inflammatory disease of the bile and pancreatic ducts. Patients were imaged with a 1.5-T superconductive magnet (Magnetom Vision, Siemens, Erlangen, Germany), a four-channel phased-array body coil, breath-hold technique, with multislice T2-weighted half-Fourier acquisition single-shot turbo spin echo (HASTE), MIP reconstructions, and a single-shot T2-weighted turbo-spin-echo sequence rapid acquisition with relaxation enhancement (RARE) with different slice thicknesses. Studies in oncological patients were completed with fat saturation 3D T1 gradient-echo sequences during the intravenous injection of gadolinium diethylene triamine pentaacetate acid (DTPA) (0.2 ml/kg). MRCP demonstrated recurrent and therefore normal bile and pancreatic ducts in 57% of patients. In the remaining 42.3%, it documented anatomical variants (41%) and congenital anomalies (1.3%). Variants of the intrahepatic bile duct were seen in 21% of cases: crossover anomaly (6.7%), anterior branch of the right hepatic duct draining the IV and VII segments that flow together with the left bile duct (3.1%) and anterior and posterior branches of the right hepatic duct that flow together with the common hepatic duct (3.3%). Variants of the extrahepatic bile ducts were present in 8.8% of patients: low insertion of the cystic duct into the common hepatic duct (4.5%), emptying of the cystic duct into the right hepatic duct (2.7%) and a second-order large branch draining into the cystic duct (1.6%). MRCP identified a double gall bladder in 3% of patients and anatomical variants of the biliopancreatic system in 8.2%: pancreas divisum (5.2%) and a long sphincter of Oddi (3%). Finally, congenital anomalies were diagnosed in 1.3% of cases: bile duct cysts (0.3%), atresia of the bile ducts (0.3%) and multiple biliary hamartomatosis (0.7%). The congenital anomalies and anatomical variants of the bile and pancreatic ducts present a complex spectrum of frequent alterations, which are worthy of attention in both the clinical and surgical settings and are readily identified by MRCP.

Brain biopsy sampling by using prospective stereotaxis and a trajectory guide.

The authors describe their initial results obtained using a skull-mounted trajectory guide for intraoperative magnetic resonance (MR) imaging-guided brain biopsy sampling. The device was used in conjunction with a new methodology known as prospective stereotaxis for surgical trajectory alignment. Between January 1999 and March 2000, 38 patients underwent 40 brain biopsy procedures in which prospective stereotaxis was performed with the trajectory guide in a short-bore 1.5-tesla MR imager. In most cases, orthogonal T2-weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) images were used to determine the desired trajectory and align the device. The surgical trajectory was defined as a line connecting three points: the target, pivot, and alignment stem points. In all cases, surgical specimens were submitted for frozen section and pathological examination. Postoperative turbofluid-attenuated inversion-recovery and gradient-echo images were obtained to exclude the presence of hemorrhage. Trajectory determination and alignment was simple and efficient, requiring less than 5 minutes. Confirmatory HASTE images were obtained along the biopsy needle as it was being advanced or after reaching the target. All biopsy procedures yielded diagnostic tissue. One patient with a lesion near the motor strip experienced a transient hemiparesis of the hand related to passage of the biopsy needle, and another sustained a fatal postoperative myocardial infarction. No patient suffered a clinically significant or radiologically visible hemorrhage. In combination with prospective stereotaxis, the trajectory guide provided a safe and accurate way to perform brain biopsy procedures.

Hydro-MRI in Crohn's disease: appraisal of disease activity.

To appraise the value of hydro-MRI in the assessment of activity in Crohn's disease. After bowel opacification with 1000 mL of an orally administered 2.5% mannitol solution was achieved, axial and coronal breath-hold sequences (T2-weighted half-Fourier acquisition single-shot turbo spin-echo sequences with or without fat saturation, dynamic T1-weighted fast low-angle shot sequences, and contrast-enhanced T1-weighted fast low-angle shot with fat saturation sequences) were acquired in 82 patients with proved Crohn's disease at 1.0 T. Enhancement of the bowel wall was correlated with other MRI findings, with the Crohn's disease activity index (CDAI), and with levels of C-reactive protein (CRP). In Crohn's disease, contrast enhancement of the affected bowel wall was markedly increased in comparison with the normal bowel wall (+80% +/- 22% versus +43% +/- 12%; P = 3 x 10(-15)). Positive correlations could be established between the increase in bowel wall enhancement and many other MRI findings. Between the increase in bowel wall enhancement and the CDAI, only a poor correlation was found (r = 0.25, P = 0.02). There was no statistical correlation between the increase in bowel wall enhancement and CRP. Hydro-MRI seems to be superior to the CDAI and CRP for the registration of Crohn's disease activity. In particular, differentiation between an active and an inactive (scarred) stenosis, which is crucial for the choice of therapeutic procedures, seems to be more reliable by the interpretation of several morphological and functional parameters on hydro-MRI than by the use of CDAI and CRP.