Reliability of endosonography in evaluation of anal fistulae and abscesses

Objective:
To assess the reliability of anal endosonography (AES) in the diagnosis of anal fistulae and abscesses. Material and Methods:
86 patients with different types of anal fistulae and abscesses were prospectively examined with a 7.0 MHz transducer. Type of anal fistulae, differentiation between simple and complex tracts, and location of their internal openings were defined. In 66 cases with permeable external opening, hydrogen peroxide solution was introduced into the fistula tract. Reliability of AES was defined after surgical treatment of all cases. Results:
74 anal fistulae, including 43 transsphincteric, 11 intersphincteric, 6 suprasphincteric, 3 superficial, and 11 ano-vaginal were found on AES. 27 fistulae were complex, and 47 simple fistulae. In 10 patients a coexisting abscess was found; the remaining 12 abscesses were without any fistula. Surgery confirmed the type of anal fistula in 64 patients (86.5%), and location of internal openings in 60 cases (81.1%). All abscesses were confirmed. Conclusion:
AES showed high accuracy in diagnosing anal fistulae and abscesses.     

Magnetic Resonance Imaging Evaluation of Perianal Fistulas

Purpose

The purpose of this study was to discuss the usefulness of magnetic resonance imaging in evaluating perianal fistulas, their ramifications, extent, associated abscesses and relations with the anal sphincter complex and its role in preoperative classification.

Material & methods

A retrospective study was carried out using picture archiving and communication system. Data of 58 patients presented with a clinical suspicious of perianal fistula from April 2012 to March 2013 was collected. In all patients pre contrast T2 propeller with and without fat suppression, diffusion weighted and pre and post contrast liver acceleration volume acquisition sequences were obtained. Pulse sequences were as follows: T2 propeller (TR: 7766 ms, TE: 122 ms), Diffusion weighted (TR: 7000 ms, TE: 67 ms), LAVA (TR: 7 ms, TE: 3.242 ms).

Results

MRI revealed a total number of 38 fistulae in 35 (60%) patients while 13 (22%) patients had only perianal sinuses. Out of these 35 patients, 4 were females and 31 were male subjects. Out of total 38 fistulae seen in these 35 patients, 11 (29%) were transsphincteric, 24 (63%) were intersphincteric and 2 (5%) were suprasphincteric. Only 1 (3%) case was extrasphincteric fistula. Twenty-six fistulae (68%) were simple, whereas 12 (32%) showed associated abscess formation, inflammation and branching course.

Conclusion

Our results support that MRI is the method of choice for evaluating perianal fistulae as they display the anatomy of the sphincter muscles orthogonally with a background of good contrast resolution. Moreover, with MRI we can accurately classify perianal fistulas preoperatively along with the detection of associated infection and help in planning a successful surgery.     

Usefulness of hydrogen peroxide enhancement in diagnosis of anal and ano-vaginal fistulas

Our objective was to assess if contrast-enhanced (CE) anal endosonography (AES) with hydrogen peroxide is useful in the diagnosis of anal and ano-vaginal fistulas. A Bruel and Kjaer scanner with a 7.0-MHz transducer was used. After visualization of the fistula tract in non-contrast (NC) AES, hydrogen peroxide was introduced into the fistula tract through the external opening in 22 patients with different types of anal fistulas. Both CE and NC AES revealed 13 transsphincteric, 3 intersphincteric, 2 suprasphincteric and 4 ano-vaginal fistulas. Simple tracts were found in 16 cases and complex in 6 cases in non-contrast AES. The CE AES revealed 19 simple and 3 complex fistulas. Fifteen internal openings visible in NC AES were confirmed in CE AES in 6 cases, which additionally found 11 more internal openings. Surgery confirmed all types of fistulas found in NC and CE AES; however, the latter two found 18 simple and 4 complex fistulas, and 21 internal openings. Both NC and CE AES are able to correctly differentiate types of anal fistulas and are of comparable value in differentiating simple from complex fistulas, although a false-negative result was found in CE AES. In the preoperative assessment of the internal opening, CE AES is superior to NC AES. Electronic Publication     

Endoanal magnetic resonance imaging of fistula-in-ano: a comparison of STIR with gadolinium-enhanced techniques

PURPOSE: To compare a STIR sequence with gadolinium-enhanced techniques on endoanal magnetic resonance (MR) imaging of fistulas-in-ano by correlating the findings with those at surgery. MATERIAL AND METHODS: Twenty-two consecutive patients with clinical suspicion of perianal sepsis were studied using an endoanal coil followed immediately by a phased array coil. T1-weighted precontrast and postcontrast and STIR images in transverse and coronal planes were produced with each coil and analysed by noting the presence and site of a collection, primary track, the position of any internal opening, and subcutaneous or supralevator extension. An "expert" and also a "trainee" radiologist assessed the images. Operative findings were similarly recorded. The Fisher exact test was used to compare imaging with surgery. Interobserver variation was calculated using a kappa statistic. RESULTS: Of 22 patients with suspected fistulas, 8 were simple, 4 were complex, and 3 were superficial sinuses. Five had no anal pathology, 1 had anal excoriation, and 1 had a polyp. At surgery, 6 intersphincteric, 1 transsphincteric, 8 extrasphincteric, no supralevator collections, and 9 internal openings were noted. The overall sensitivity and specificity for detecting these were 75% and 64%, respectively, for STIR imaging, and 58.3% and 62.8% for gadolinium-enhanced imaging. There was good agreement between the "trainee" and the "expert" in the interpretation of images (kappa=0.7). CONCLUSION: A STIR sequence is more sensitive overall than gadolinium-enhanced techniques on endoanal magnetic resonance imaging of fistulas-in-ano because of increased sensitivity in detecting the internal opening. A combination of endoanal and phased array techniques using STIR imaging sequences is valuable preoperative assessment in both simple and complex cases.     

Endoanal MRI of perianal fistulas: the optimal imaging planes

Twenty consecutive patients with the clinical suspicion of a perianal fistula were studied to define the optimal and time-efficient imaging planes for endoanal MRI in the identification and classification of perianal fistulas. The duration of each part of the MR procedure was recorded in all patients. Off-axis axial (A), coronal (C), sagittal (S) and radial (R) T2-weighted sequences were performed in all patients. Sets of images and combinations of images (A; R; CS; AR; ACS; ARCS) without patient data were reviewed in masked fashion and independently with a 2-month interval between each set. The reader was masked to the results of previous readings. The findings were compared with the surgical findings. The number of correctly identified and classified fistula and the sensitivity and specificity were determined. Twenty fistulas were present at surgery: 14 transsphincteric fistulas and six intersphincteric fistulas. Eighteen fistulas were correctly identified with the radial (R) and combined coronal sagittal (CS) sequences. In all other sequences or combinations of sequences all 20 fistulas were identified. Classification was correct with A in 16 patients, with R in 15, with CS in 15, with AR in 18, with ACS in 17 and with ARCS in 18. The sensitivity and specificity were optimal using AR or ARCS (0.86 and 1 respectively). The optimal and most time-efficient imaging protocol for endoanal MRI of perianal fistulas thus comprises the axial and radial imaging planes. Received 29 September 1997; Revision received 13 February 1998; Accepted 17 March 1998     

肛瘘磁共振成像:探讨自制可调节肛肠水囊在肛瘘分级中的价值

目的:探讨普通MR成像中使用自制可调节肛肠水囊在肛瘘患者分级中的应用价值.方法:18例经手术证实的肛瘘患者于使用自制可调节肛肠水囊前、后均各行一次MRI检查.序列包括T_1 WI横断位和冠状位、T_2 W SPAIR横断位,冠状位及矢状位.放置水囊前后比较瘘管末端位置,并且对瘘管、内口、分支及脓腔进行计数,同时观察瘘管走行.所获结果被用于评估肛瘘MR诊断分级,并同时与手术结果相对照.结果:18名肛瘘患者MRI检查共发现瘘管31根、内口22个、分支19根以及脓腔10个.使用水囊前后MRI对瘘管末端位置的显示有显著不同(χ~2=5.56,P<0.05).使用水囊前,MR显示1例1级低位单纯线形括约肌内肛瘘,1例低位和2例高位2级括约肌内肛瘘伴脓肿或分支,1例3级高位经括约肌肛瘘,6例4级经括约肌肛瘘伴脓肿或分支,其中5例为高位,1例为低位,2例5级高位肛提肌上和经肛提肌肛瘘,另有5例无法确定;使用水囊后,2级高位括约肌内肛瘘伴脓肿或分支上升为3例,4级低位经括约肌肛瘘伴脓肿或分支上升至2例,高位上升至7例,另有1例无法确定,余小变.使用水囊前后,M RI对肛瘘分级与手术的相符率分别为72%(13例)和94%(17例).结论:通过使用自制町凋节肛肠水囊,普通M RI能够获得更多有关瘘管及其走行的信息,有助于肛瘘患者的分级.     

Local staging of rectal cancer using combined pelvic phased-array and endorectal coil MRI

PURPOSE: To assess the accuracy of MRI, using a pelvic phased-array coil and an endorectal coil, for preoperative local staging of rectal cancer. MATERIALS AND METHODS: Fifty-one patients (26 males and 25 females) with adenocarcinoma of the rectum underwent preoperative MRI and surgical resection of their tumors. Surgical pathology staging was compared to MRI staging (using the TNM classification) obtained both retrospectively by a reader blinded to surgical findings and prospectively (radiological reports). In addition, patients were stratified according to surgical treatment groups (stage I = T1-2/N0, stage II = T3/N0, stage III = Tx/N1-2). RESULTS: At pathology, 36 of 51 (68%) tumors were classified as T0-T2, and 15 (32%) were classified as T3. Overall, the sensitivity and specificity of MRI readings for T3 staging were 93% and 86%, respectively (positive predictive value (PPV) = 74%, negative predictive value (NPV) = 97%, accuracy = 88%). MRI correctly predicted lymph node metastases in 11 of 13 patients with a sensitivity of 85% and specificity of 69% (PPV = 58%, NPV = 90%, accuracy = 74%). MRI correctly predicted surgical treatment groups in 33 of 39 (85%) patients. Interobserver agreement between the retrospective and prospective readings was excellent (kappa = 0.85) for prediction of T3 tumor and good (kappa = 0.80) for prediction of nodal involvement. CONCLUSION: Combined endorectal and pelvic phased-array coil MRI can be used reliably to select which patients should receive preoperative chemoradiotherapy. It is highly predictive in terms of excluding T3 tumors, but still has limitations in predicting lymph node metastasis.     

Transperineal and transvaginal sonography of perianal inflammatory disease

OBJECTIVE: Perianal infection arises in small intersphincteric anal glands predominantly located at the dentate line. Documentation of fluid collections and the relationship of inflammatory tracts to the sphincter mechanism is important for surgical treatment. Transanal sonography for assessment of perianal inflammatory disease is limited because placement of the rigid probe into the anal canal does not allow assessment of disease in the perineal region. The purpose of this study was to validate the use of transperineal sonography in men and both transvaginal and transperineal sonography in women for evaluation of perianal inflammatory disease. SUBJECTS AND METHODS: Fifty-four patients, 28 men and 26 women, were imaged with transperineal and a combination of transperineal and transvaginal sonography, respectively. All patients were examined in the supine lithotomy and left lateral position with a transvaginal 8-to 4-MHz probe or a linear 12- to 7-MHz transducer. All fluid collections, sinus tracts, and fistulas were described by their location in relation to the sphincter mechanism and perineum. RESULTS: Forty-six of 54 patients had perianal fistulas or sinus tracts: 33 transphincteric, seven intersphincteric, and six extrasphincteric. Fifteen patients had an associated abscess. In the eight remaining patients, there were two anovaginal fistulas, one rectovaginal fistula, one prolapsed internal hemorrhoid, two perianal complex masses, and two vascular perianal or perirectal inflammatory masses. Twenty-six patients underwent surgical procedures involving the anorectal canal or perirectal region, and of these, preoperative sonographic findings were confirmed in 22 (85%) of 26 patients. Three patients refused surgery, and six are awaiting surgery at this writing. Fifteen patients were treated conservatively. CONCLUSION: Transperineal and transvaginal sonography are accurate, painless, and cost-effective methods for documenting perianal fluid collections and fistulas or sinus tracts or both.     

Magnetic resonance imaging evaluation of perianal fistula

Aim of work

To clarify the role of MRI in diagnosis and classification of perianal fistula and to evaluate the additional clinical value of preoperative MR imaging and its benefit to surgeon.

Methods

This prospective study contained 25 patients (21 males and 4 females; age range 10–60 years; mean age 34.8 years) selected from 40 patients referred to the Radiodiagnosis department with perianal sepsis, the study was conducted between October 2009 and September 2011, MRIs were performed and the results were ensured by surgical results, sensitivity, specificity and predictive values of MRIs were determined.

Results

25 patients with perianal sepsis were included in this study, 3 cases grade 1 (simple linear intersphincteric fistula), 2 cases grade 2 (intersphincteric fistula with abscess or secondary track), 9 cases grade 3 (trans-sphincteric fistula), 9 cases grade 4 (trans-sphincteric fistula with abscess (5 cases), secondary track within the ischiorectal fossa (3 cases) and both (1 case)) and 2 cases grade 5 (supralevator and translevator disease one case for each).

Conclusion

MRI is a useful procedure for successful management of peri-anal fistula by correct assessment of the extent of disease and relationship to sphincter complex. Also it helps in identification of secondary extensions, particularly horseshoe tracts and abscesses resulting in complete evaluation and highest possible diagnostic accuracy aiding successful surgical interventions, aiming to reduce complications and recurrences.     

MRI for preoperative staging of renal cell carcinoma using the 1997 TNM classification: comparison with surgical and pathologic staging

OBJECTIVE: The purpose of our study was to determine the accuracy of MRI for preoperative staging of renal cell carcinoma using the 1997 TNM classification. MATERIALS AND METHODS: We conducted a retrospective review of MRI performed in 40 consecutive patients with 42 renal cell carcinomas before radical (n = 35) or partial (n = 4) nephrectomy or exploratory laparotomy (n = 3). The interval between imaging and surgery ranged from 1 to 59 days (mean, 17.9 days). Imaging was performed with T1- and T2-weighted, dynamic gadolinium-enhanced, and time-of-flight sequences. MRI and surgical-pathologic staging was performed using the 1997 TNM staging system. MRI staging was compared with surgical-pathologic staging as the gold standard. Agreement between the two staging methods was assessed using the kappa statistic. RESULTS: Agreement between MRI and surgical-pathologic staging was good for T staging (kappa = 0.72 and 0.78 for reviewers 1 and 2 respectively), poor for N staging (kappa = 0.13, both reviewers), good for M staging (kappa = 0.66, both reviewers), and excellent for the assessment of venous involvement (kappa = 0.93, both reviewers). MRI overestimated the T stage in five patients and the N stage in five and underestimated the T stage in three, the N stage in four, the M stage in one, and the extent of venous thrombosis in two patients. CONCLUSION: MRI is a reliable method for preoperative staging of renal cell carcinoma using the 1997 TNM classification, in particular for assessing venous involvement.     

高分辨率MRI扩散加权成像对直肠癌术前T、N分期及环周切缘判断的价值

目的探讨高分辨率MRI扩散加权成像(DWI)对直肠癌患者术前T、N分期与环周切缘的判断价值。方法对收治的直肠癌127例患者行MRI与DWI检查,根据术后病理结果,分析MRI与DWI对直肠癌术前T分期与N分期的诊断价值以及对环周切缘的判断价值。结果MRI诊断T1期敏感度92.00%、特异度99.02%;T2期敏感度92.31%、特异度97.03%、T3期92.68%、特异度98.84%;T4期敏感度91.43%、特异度100.0%。MRI对N0期诊断敏感度93.02%、特异度94.05%、N1期敏感度89.13%、特异度97.53%、N2期敏感度93.33%、特异度100.0%。经单因素方差分析显示,不同分期患者b=800 mm^2/s基线下ADC值,差异具有统计学意义(P<0.05);其中T1、T2、T3期ADC值显著高于T4期,T1期显著高于T2、T3期,差异具有统计学意义(P<0.05)。b=800 mm^2/s基线下ADC值对T1期直肠癌患者的AUC为0.834、对T2期0.651、T3期0.546、T4期0.837。经单因素方差分析显示不同N分期患者ADC值,差异具有统计学意义(P<0.05)。结论MRI诊断直肠癌患者术前T、N分期具有较高价值,而DWI检查中b值基线下ADC在一定程度上可反映肿瘤细胞分化程度。     

Added value of MRI to endoscopic and endosonographic response assessment after neoadjuvant chemoradiotherapy in oesophageal cancer

In order to select oesophageal cancer patients after neoadjuvant chemoradiotherapy (nCRT) for organ-preserving treatment instead of surgery, a high diagnostic accuracy is required. The aim of this study was to evaluate whether MRI had additional value to gastroscopy with biopsies and endosonographic ultrasound (EUS) with fine needle aspiration (FNA) for the detection of residual tumour after nCRT. Twenty-two patients with oesophageal cancer eligible for nCRT followed by oesophagectomy were prospectively included. All patients underwent (T2- and diffusion-weighted) MRI and gastroscopy+EUS before and after nCRT. Histopathology after oesophagectomy was the reference standard with pathological complete response (pCR) defined as ypT0N0. Diagnostic performance regarding the detection of residual tumour was calculated for gastroscopic biopsies and for EUS-FNA without and with MRI. Nineteen of the 22 patients (86%) did not achieve pCR after nCRT (7 ypT+N+, 11 ypT+N0, 1 ypT0N+). Biopsies detected residual tumour in 6 of 18 ypT+ patients. After adding MRI, 16 of 18 residual tumours were assessed correctly. EUS-FNA detected 3 out of 8 ypN+ patients, while MRI did not improve detection. Overall, adding MRI improved sensitivity for detection of residual tumour to 89% (17 of 19) from 47% (9 of 19) with endoscopic biopsies and EUS-FNA only. In this small study, the detection of residual tumour after nCRT in oesophageal cancer patients was improved by the addition of MRI to gastroscopy and EUS. • In this small study, the detection of residual tumour after neoadjuvant chemoradiotherapy in oesophageal cancer patients was improved by adding MRI including diffusion-weighted images to gastroscopy and endosonographic ultrasound. • With the addition of MRI assessment to gastroscopy and endosonographic ultrasound, the considerable risk of missing residual tumours decreased from 53 to 11%, while the pitfall was overstaging in one out of three complete responders.     

Magnetic resonance imaging of pyomyositis in 43 cases

PURPOSE: To describe the magnetic resonance imaging (MRI) findings in pyomyositis. METHODS AND MATERIALS: Forty-three patients with proven muscle infection (30 males, 13 females) ranging in age from 14 to 86 years (mean 42 years) were studied with MRI. The initial clinical diagnose were soft tissue infection (n=27), neoplasm (n=12), thrombophlebitis (n=3), and lymphedema (n=1). Spin-echo T1- and T2-weighted images were obtained in all cases and STIR sequence in 6. Spin-echo T1-weighted images after Gd-DTPA injection were obtained in 16 cases. The signal intensity findings, the extent of the abnormalities in the soft tissue (muscle, fascial and subcutaneous involvement), the presence of fluid collections, and the involvement of neighbouring bone and joint were reviewed retrospectively. RESULTS: A hyperintense signal on T2-weighted and STIR images were detected in all patients. Fluid collections were seen in 21 cases as localized areas of hypointensity on the T1-weighted images, and highly hyperintense areas on the T2-weighted images. In four patients a rim of high signal intensity was seen around the fluid collection on the T1-weighted images. On contrast-enhanced T1-weighted images there was diffuse enhancement in the patients without fluid collections that was heterogeneous in seven and homogeneous in two. After Gd-DTPA all fluid collections showed a central area without enhancement and a well-defined enhancing peripheral rim. Involvement of adjacent structures included subcutaneous tissue (n=25), bone marrow (n=14), fascial planes (n=15) and joints (n=11). CONCLUSION: MRI is useful in the assessment of pyomyositis and in determining the location and extension. A hyperintense rim on unenhanced T1-weighted images and peripheral enhancement after Gd-DTPA are useful for identifying the number, size, and location of soft-tissue abscesses.     

Accuracy of High-Resolution MRI with Lumen Distention in Rectal Cancer Staging and Circumferential Margin Involvement Prediction

Objective

To evaluate the accuracy of magnetic resonance imaging (MRI) with lumen distention for rectal cancer staging and circumferential resection margin (CRM) involvement prediction.

Materials and Methods

Seventy-three patients with primary rectal cancer underwent high-resolution MRI with a phased-array coil performed using 60-80 mL room air rectal distention, 1-3 weeks before surgery. MRI results were compared to postoperative histopathological findings. The overall MRI T staging accuracy was calculated. CRM involvement prediction and the N staging, the accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were assessed for each T stage. The agreement between MRI and histological results was assessed using weighted-kappa statistics.

Results

The overall MRI accuracy for T staging was 93.6% (k = 0.85). The accuracy, sensitivity, specificity, PPV and NPV for each T stage were as follows: 91.8%, 86.2%, 95.5%, 92.6% and 91.3% for the group ≤ T2; 90.4%, 94.6%, 86.1%, 87.5% and 94% for T3; 98,6%, 85.7%, 100%, 100% and 98.5% for T4, respectively. The predictive CRM accuracy was 94.5% (k = 0.86); the sensitivity, specificity, PPV and NPV were 89.5%, 96.3%, 89.5%, and 96.3% respectively. The N staging accuracy was 68.49% (k = 0.4).

Conclusion

MRI performed with rectal lumen distention has proved to be an effective technique both for rectal cancer staging and involved CRM predicting.     

Image-guided surgery for anal fistula in a 0.5T interventional MRI unit

PURPOSE: To determine whether MR-guided anorectal surgery is feasible, and to develop techniques for MR-guided anal fistula surgery. MATERIALS AND METHODS: Six patients with pilonidal sinus (PNS), and 21 with suspected anal fistulae were operated on in the GE Signa SPIO 0.5T interventional MRI unit. Procedures were performed with magnet-safe Lockhart-Mummery fistula probes. Preprocedural and intra-operative MRI (IOMRI) techniques were used to identify the extent of the fistula tracts and septic foci, and to ensure the adequacy of the surgical procedure. RESULTS: IOMRI demonstrated the PNS lesions and the adequacy of excision. Imaging failed to demonstrate a fistula in two patients, as confirmed by surgical examination. No images were obtained in one patient due to his size (weight in excess of 100 kg). In 18 patients a fistula tract or abscess was demonstrated and IOMRI was used to assess the adequacy of the surgical procedure. In three patients this demonstrated incomplete drainage of septic foci, which was not obvious on inspection of the surgical field. We believe that in these patients IOMRI prevented an incomplete procedure and the potential requirement for a second operation. Further surgery was performed to rectify this situation. The fistula tract was laid open in 13 patients, and a Seton drain was inserted in five. CONCLUSION: MRI-guided surgery for anal fistula is feasible. IOMRI demonstrates the exact anatomy of the tracts and abscesses, and confirms that all have been adequately treated. We believe it may become particularly useful in surgery for recurrent and complex anal fistulae, and may lead to fewer recurrences.     

MR cisternography: a new method for the diagnosis of CSF fistulae

The aim of this study was to compare a new MRI method for detecting the existence of cerebrospinal fluid (CSF) fistulae, i. e. MR cisternography, with CT cisternography. In a prospective study, 30 patients with post-traumatic CSF fistulae were examined. The MR examinations were performed with a 1.0-T whole-body MR system, using two T2^*-weighted sequences, a 3D PSIF (time-inversed fast imaging with steady-state precession, FISP) and a 3D constructive interference steady-state (CISS) sequence. The results of MRI and CT cisternography were compared with the surgical findings. The sensitivity in detecting CSF fistulae with MR cisternography (PSIF: 89.9 %; CISS: 93.6 %) was higher than with CT cisternography (72.3 %). The sensitivity of CT cisternography at detecting CSF fistulae in patients with a size of dural lesion less than 2 mm or in patients with multiple dural lesions is significantly lower compared with the MR method. Although the localization of CSF fistulae always proved possible with MR cisternography, this could only be accomplished wih CT in 70 % of cases. The MR cisternography technique is a new examination method with a higher sensitivity for the detection of CSF fistulae than CT cisternography. The CISS technique is superior compared with PSIF and should be used in patients with high-flow CSF fistulas. Received 15 July 1996; Revision received 15 January 1997; Accepted 25 February 1997     

Diffusion-weighted magnetic resonance imaging detects early neuropathology following four vessel occlusion ischemia in the rat

Early neuropathology following a prolonged duration of four-vessel occlusion (4 VO) ischemia in the rat was charted using magnetic resonance imaging (MRI). Animals received either 30 minutes of 4 VO (N = 6) or sham operation (N = 6) prior to in vivo assessment. Proton density and T(2) and combined T(2)/diffusion-weighted (T(2)/DW) MRI were performed at 6, 24, and 72 hours postocclusion. T(2)/DW imaging was the most effective sequence for delineating between injured and intact tissues, indicating neuropathology in the dorsolateral striatum at 24 hours and in the CA1/CA2 subfields of the hippocampus at 72 hours following ischemia. Apparent diffusion coefficient values were significantly reduced in the striatum (P = 0.03) and hippocampus (P = 0.005) at 24 and 72 hours, respectively. This is the first report, to our knowledge, of T(2)/DW imaging detecting lesions following 4 VO in accord with the known temporal evolution of ischemic brain damage.     

Value of contrast enhanced spoiled gradient (SPGR) MR and MIP MR imaging in diagnosis of peri-anal fistula

Purpose

To assess the value of the combination of contrast enhanced T1 spoiled gradient (SPGR) MR and maximum intensity projection (MIP) MR imaging in the complete pre-operative evaluation of peri-anal fistula.

Patients and methods

This prospective study contained 28 patients with clinical diagnosis of peri-anal fistula, they were performed MRI using the following sequences in both axial and coronal planes: Pre contrast T2FSE, T1FSE and Post contrast SPGR. MIP reformated images were done using the SPGR sequence. Fistulas were classified according to Parks (6) classification, they were evaluated regarding site, type, extensions, complications and diagnostic accuracy of each sequence. Our findings were correlated with operative findings.

Results

Fourteen patients had inter-sphincteric fistulas (50%), 8 patients had trans-sphincteric fistulas (28.6%) and 6 patients had supra-sphincteric fistulas (21.4%). Simple non branching tracts were found in 22 patients, branching tracts in 6 patients, abscess cavity in 5 patients, horseshoe extension in 4 patients. Overall diagnostic accuracy of post contrast T1 SPGR was 97.3% and MIP MR imaging was 100%. Post contrast T1 SPGR accurately evaluated all patients but missed one faint horseshoe extension and other fine para anal branches. MIP imaging accurately evaluated all the extensions and ramifications but was poor in depth orientation.

Conclusion

MRI is a reliable diagnostic modality in the evaluation of peri-anal fistulas. Post contrast T1 SPGR sequence with its high resolution images and excellent anatomical orientation provides almost all the necessary details for accurate evaluation. Although MIP images lack depth orientation their high sensitivity, rotational 2D and 3D capabilities exquisitely depict all the fine ramifications and extensions. The combination of both provides complete evaluation and highest possible diagnostic accuracy aiding successful surgical interventions, aiming to reduce complications and recurrences.     

Time-resolved contrast-enhanced MR angiography of intracranial lesions

PURPOSE: To determine if contrast-enhanced (CE) MRI of intracranial lesions benefits from time-resolved MR angiography (MRA) during contrast agent injection. MATERIALS AND METHODS: For 126 patients with suspected intracranial lesions undergoing routine CE MRI at 3.0T (N = 88) or 1.5T (N = 38), time-resolved CE MRA (three-dimensional [3D] time-resolved imaging of contrast kinetics [TRICKS]) was performed during injection of the routine gadolinium (Gd) dose of 0.1 mmol/kg. Time to peak (TTP) enhancement of lesions as well as time to internal carotid artery (ICA), middle cerebral artery (MCA), superior sagittal sinus (SSS), and jugular vein enhancement were measured. Source and maximum intensity projection (MIP) images were reviewed to delineate the spatial relationship of lesions and the vasculature. RESULTS: In 61 patients (48%), additional important findings were detected on time-resolved MRA that were not seen on the routine CE protocol, including aneurysms (N = 6), arteriovenous malformations (N = 7), ICA stenoses (N = 2), vascular anomalies (N = 18), and relationships between lesions and vessels (N = 28). In addition, tumor TTP correlated with glioma grade (r = 0.87) and discriminated epithelial from nonepithelial meningiomas (P = 2.6 x 10(-5)). MRA added eight minutes to the total exam time. CONCLUSION: Time-resolved MRA performed during contrast agent injection adds information to the routine brain CE MRI examination of intracranial lesions with only a small time penalty and no additional risk to the patient.     

The place of MRI in the study of cerebrospinal fluid fistulas

Results of CT and MRI explorations in 8 patients with cerebrospinal fluid (CSF) fistulae are reported and compared with surgical findings in 7. Sensitivity of MRI (CISS and fast T2 spin-echo sequences) was excellent giving perfect correlations with surgical findings in 7/7 cases. CT and MRI were found to provide complementary information suggesting they should be used in combination as first intention explorations of suspected CSF fistulae. Computerized cisternography should be used if MRI is contraindicated or if a clinically and biologically proven CSF fistulae is not visualized by CT or MRI.