Magnetic resonance imaging of the anal sphincter using an internal coil.

A surface coil placed within the anal canal was used to image the anal sphincter and determine normal anatomy and contrast enhancement patterns as well as appearances in disease. Sixteen normal volunteers and 24 patients were examined. Imaging was performed on a 0.5-T Picker Asset and a 1.0-T Picker HPQ Vista MRI scanner. T1-weighted and T2-weighted spin-echo, T1-weighted gradient-echo, STIR images transverse to the sphincter, and T1-weighted spin-echo images parallel to the sphincter in the coronal oblique plane were obtained. Intravenous gadopentetate dimeglumine (0.1 mmol/kg) was given to two normal subjects and 10 patients. The coil was easy to insert and well-tolerated and provided high spatial resolution. The internal sphincter had a higher signal intensity than the external sphincter on all sequences but particularly on STIR images. Brisk contrast enhancement of the internal sphincter was seen. Sphincteric abscesses and fistulous tracks were identified in three patients and confirmed at surgery. Sphincter defects were seen in three patients with obstetric trauma, and these were confirmed at surgery. Sphincter atrophy was seen in four patients with idiopathic fecal soiling. High resolution magnetic resonance imaging with a dedicated endoanal coil provides excellent visualisation of normal anatomy and pathology in and around the anal sphincter and may be of considerable value in diagnosis.

A solid reusable endorectal receiver coil for magnetic resonance imaging of the prostate: design, use, and comparison with an inflatable endorectal coil.

We have designed a solid endorectal receiver coil for MRI of the prostate. The coil provided an improved signal-to-noise ratio up to 5 cm from its surface when compared with a standard pelvic phased array. This preliminary report describes 16 patients who were imaged using this coil, seven of whom had been examined previously with a balloon-design endorectal coil. Patient tolerance of these coils was compared. The solid coil was easy to insert and quick to set up because it did not require external tuning and matching. It avoided uncomfortable rectal distension experienced with the balloon coil as well as susceptibility artifacts from air in the balloon. In addition, it could be sterilized and reused.

MRI of fistula-in-ano: a comparison of endoanal coil with external phased array coil techniques.

PURPOSE: The objective of our study was to compare MRI of fistulas-in-ano using an endoanal coil with that using a pelvic phased array coil and to assess the value of a combined approach by correlating the findings with those at surgery. METHOD: Twenty consecutive patients with clinical suspicion of perianal sepsis were studied using an endoanal coil immediately followed by a phased array coil. T1 weighted and STIR images in transverse and coronal planes were made with each coil and analysed by noting the presence and site of a collection and primary track, the position of any internal opening, and subcutaneous or supralevator extension. Operative findings were similarly recorded. RESULTS: Of 20 patients with suspected fistulas, 8 had simple fistulas, 8 had complex fistulas, and 4 had no current evidence of infection. The concordance between MR and surgery for identifying the presence and site of the collection, the primary track, and the internal opening in both simple and complex cases was superior using the endoanal coil as compared with the phased array. Both coils together reflected the findings of the endoanal coil used alone. However, for supralevator/subcutaneous extension, concordance was superior using the phased array compared with the endoanal coil, and a combined approach reflected the values of the phased array coil used alone. CONCLUSION: Endoanal MRI is highly sensitive in the delineation of fistulas-in-ano. In combination with phased array techniques, it provides valuable preoperative assessment in both simple and complex cases.

Endoscopic laser ablation of the prostate (ELAP): changes in magnetic resonance imaging and clinical outcome at 1 year.

OBJECTIVE: To assess the ability of magnetic resonance imaging (MRI) to detect tissue changes immediately after laser ablation of the prostate and to correlate these changes with clinical outcome by detecting changes that may improve the outcome by allowing the laser dosimetry to be adjusted during therapy by monitoring effects on gland morphology. PATIENTS AND METHODS: Eight men with proven bladder outlet obstruction had a standard four-quadrant laser ablation of the prostate with a side-firing non-contact fibre. MRI scans were performed before, during and immediately after treatment and again after one week, 3 months and one year. RESULTS: The clinical outcome was a decrease in the American Urological Association (AUA)-7 symptom score from a pre-operative mean of 21.3-12.0 1 year after treatment and a corresponding increase in peak urinary flow rates from a mean of 8.9 mL/s to 12.3 mL/s. Immediately after treatment, MRI showed marked swelling of the gland (mean increase in volume 34%, range 12-75) with the loss of internal architecture. A low-signal thin periurethral band was present in six of the eight patients after 1 week and was replaced by a wider periurethral ring at 3 months in four of the six patients. No patient had evidence of prostatic cavitation after treatment or a significant reduction in prostate volume at 1 year. CONCLUSION: MRI can detect tissue changes after laser ablation of the prostate. The marked swelling seen on MRI immediately after laser prostatectomy may explain the delayed improvement in symptoms. The periurethral ring may indicate the depth to which laser energy has an effect on the tissue and could delineate an area of necrosis. The lack of cavitation at one year questions the durability of the effect of laser treatment delivered in this way.

Magnetic resonance imaging guided breast biopsy using a frameless stereotactic technique.

The high sensitivity but poor specificity of contrast enhanced magnetic resonance (MR) imaging for delineating malignant breast lesions is increasing the demand for MR guide breast biopsy. However, the poor patient access offered by conventional MR systems makes such procedures extremely difficult. We describe a method of performing breast biopsy outside the bore of the magnet using the 3-D MR imaging data. This involves a frameless stereotactic technique using an ultrasonic localizer. The position in space of the tip of a pointer with a handle which incorporates two ultrasound emitters can be tracked using an array of ultrasound detectors. MR visible marker beads (fiducials) placed on the breast and imaged at the same time are identified to the computer in relation to images of the breast. The ultrasonic localizer is used to register the position in space of the fiducials by touching them with the tip of the pointer. The image of the lesion within the breast can then be displayed in relation to the position of the tip of the pointer and the needle approach planned. Nine women with foci of enhancement on their dynamic contrast enhanced MR images underwent frameless stereotactic breast cytology. Needle placement within 2 mm of the lesion was achieved at first pass in eight out of nine (89%) cases: in one case the needle had to be re-positioned prior to sampling. This technique provides a means of targetting MR visible lesions using the MR imaging data whilst performing the procedure outside the magnet bore.

MRI of the anal sphincter.

OBJECTIVE: The anal sphincter was imaged with MR using an internal coil to demonstrate its anatomy, contrast enhancement patterns, and appearance in disease. MATERIALS AND METHODS: A cylindrical saddle geometry coil was placed in the anal canal. Sixteen volunteers and 18 patients were examined. Imaging was performed on a 0.5 T Picker Asset MRI scanner in all the volunteers and nine patients and on a 1.0 T Picker HPQ Vista in nine patients. Then T1- and T2-weighted SE, T1-weighted GE and STIR images transverse to the sphincter, and T1-weighted SE images parallel to the sphincter in the coronal oblique plane were obtained. Intravenous gadopentetate dimeglumine (0.1 mmol/kg) was given to 2 normal subjects for dynamic studies and 10 patients for conventional postcontrast imaging. RESULTS: The coils were easy to insert and well tolerated and provided high spatial resolution. The internal sphincter had a higher signal intensity than the external sphincter on all sequences but particularly on STIR images. Brisk contrast enhancement of the internal sphincter was seen. Sphincteric abscesses and fistulous tracks were identified in three patients and confirmed at surgery. Sphincter defects were seen in three patients with past obstetric trauma, and these were also confirmed at surgery. Sphincter atrophy was seen in three patients with idiopathic fecal soiling. CONCLUSION: MRI of the anal sphincter with an internal coil provides excellent visualization of normal anatomy and may be of considerable value in diagnosis.

High resolution magnetic resonance imaging of the anal sphincter using a dedicated endoanal coil. Comparison of magnetic resonance imaging with surgical findings.

PURPOSE: To obtain high resolution images of the anal sphincter and adjacent anorectum using an endoanal coil in patients with sepsis, trauma, and low rectal tumors and to compare imaging appearances with findings at time of surgery. PATIENTS AND METHODS: A cylindrical saddle geometry coil (diameter, 9 mm; length, 75 mm) was used to examine 30 patients (mean age, 53.6 years). Pathologies included perianal sepsis (10 patients), obstetric trauma (7 patients), and low rectal tumors (13 patients). Imaging was performed on an 0.5-T Picker Asset or 1.0-T Picker HPQ Vista (Picker International, Highland Heights, OH). T1 and T2 weighted and short inversion time inversion recovery transverse images and T1 weighted coronal images were obtained. Intravenous gadopentetate dimeglumine (0.1 mmol/kg) was given to all patients with suspected infection and neoplasms. RESULTS: Abscesses and fistulas identified using magnetic resonance imaging (MRI) in patients with perianal sepsis were confirmed at surgery in all cases; site of fistulous internal opening into the anal canal was correctly identified in 80 percent of cases. Extent of sphincter tear was correctly assessed on endoanal MRI in all patients with obstetric trauma when compared with surgical findings. Tumor invasion of anal sphincter was seen in 38.5 percent of low rectal carcinomas. CONCLUSIONS: MRI with an endoanal coil provides detailed images of the site and extent of anal fistulas, sphincter tears, and local tumors and is of considerable value in preoperative assessment.

MR imaging of the anal sphincter in multiparous women using an endoanal coil: correlation with in vitro anatomy and appearances in fecal incontinence.

OBJECTIVE: The aim of this study was to correlate the components of the normal female anal sphincter seen on high-resolution MR images with the in vitro anatomy and to describe the change in appearances of these components in multiparous women with fecal incontinence. SUBJECTS AND METHODS: Ten asymptomatic female volunteers (32-72 years old; mean, 54 years old) and 22 women with fecal incontinence were studied. In six patients (26-68 years old; mean, 49 years old) fecal incontinence began immediately after childbirth; in the remaining 16 patients (45-77 years old; mean, 58 years old) fecal incontinence developed 15- 30 years after childbirth. In the latter group of patients, terminal motor latencies of the pudendal nerve were measured. Imaging was done on a 0.5-T Picker Asset unit and on a 1.0-T Picker HPQ unit. A saddle geometry endoanal receiver coil was used for all imaging. T1-weighted spin-echo (720-820/20 [range of TR/TE]), T2-weighted spin-echo (2500/80 [TR/TE]), fast spin-echo (4500/96 [TR/ effective TE]), and short inversion time inversion recovery (2500/80 [TR/TE]; inversion time, 107 msec) MR images were obtained in transverse, coronal oblique, and sagittal planes. Images were assessed for integrity of the sphincter components. A nonpaired separate-variance t test was used to compare thickness of individual muscle components between patients with delayed-onset fecal incontinence and asymptomatic age-matched volunteers. Degree of muscle atrophy was correlated with degree of delay in the terminal motor latency of the pudendal nerve. RESULTS: The high resolution obtained with an endoanal coil allowed differentiation of the various muscle components of the anal sphincter complex. The internal sphincter was seen as a ring of homogeneously high signal intensity with a low-signal-intensity rim that was rich in collagen and contained neurovascular bundles. The external anal sphincter, which had low signal intensity on T1- and T2-weighted images, was shown as three components: subcutaneous, superficial, and deep. In six patients who had fecal incontinence that began immediately after childbirth, endoanal MR imaging revealed the site and extent of a tear. All tears were confirmed at surgery. In the 16 patients who had fecal incontinence that began several years after childbirth, atrophy of the external sphincter was revealed in all cases in the superficial and deep components. The internal sphincter remained normal. However, we found that the degree of atrophy of individual components of the external sphincter did not correlate with the degree of delay in pudendal nerve conduction. CONCLUSION: MR imaging with an endoanal coil reveals the integrity and bulk of individual muscle components of the anal sphincter in multiparous women with fecal incontinence.

MR-guided biopsy of the breast after lumpectomy and radiation therapy using two methods of immobilization in the lateral decubitus position.

We describe two methods of breast immobilization using the lateral decubitus position to increase patient comfort and access to the axillary tail for MR-guided biopsy in the postsurgical or irradiated breast. The first method uses a compression device with good immobilization but poor patient tolerance. The second approach uses a thermoplastic mesh material to form a rigid exoskeleton around the breast: immobilization is adequate and patient acceptability is good. The latter method is preferred and requires formal evaluation in larger scale trials.

Endoscopic laser ablation of the prostate: MR appearances during and after treatment and their relation to clinical outcome.

OBJECTIVE: Endoscopic laser ablation is a new treatment for benign prostatic hypertrophy. The objectives of this study were to determine the appearances of the prostate on MR images obtained during, 1 week after, and 3 months after this procedure and to determine if a correlation exists between the MR findings and the clinical outcome. Such appearances could then be used to guide the application of laser energy during the procedure in order to optimize the clinical result. SUBJECTS AND METHODS: Eight consecutive men 58-74 years old with symptoms of bladder outflow obstruction caused by benign prostatic hypertrophy underwent endoscopic laser ablation of the prostate under spinal or epidural anaesthesia. Imaging was done on a 0.5-T Picker Asset system with an endorectal receiver coil and conventional T1-weighted spin-echo, T2-weighted spin-echo, and gradient-recalled-echo sequences. T1-weighted magnetization transfer images were obtained in three patients. Images were obtained preoperatively, after ablation of the left-sided quadrants, immediately after completion of the procedure, and 1 week and 3 months later. Preoperative and 3-month postoperative symptom scores, peak urine flow rates, and bladder residual volumes were studied. Images were visually assessed for signal-intensity changes and the presence of cavitation by three radiologists in conference. The results were quantitatively analyzed by measuring prostatic volumes on the gradient-recalled-echo images and by measuring the width and area of regions of signal-intensity change on the T2-weighted images. RESULTS: MR images made immediately after treatment showed an increase in the volume of the prostate (mean, 34%) and a poorly defined, low-signal-intensity region around the urethra on the T2-weighted images in six patients. This probably represented coagulative necrosis. The prostate was smaller on MR images made 1 week after treatment, and after 3 months the prostate returned to its preoperative size. After 1 week, the low-signal-intensity periurethral region on the T2-weighted images was less obvious, and at 3 months it was replaced in four patients by a well-demarcated low-signal-intensity ring on the T2-weighted and gradient-recalled-echo images. No evidence of cavity formation in the prostate was seen on MR images in any patient. Symptom scores and peak urinary flow rates improved after 3 months, with a significant difference between the mean increase in symptom scores in the patients with and without the periurethral changes seen immediately after treatment. However, we found no significant difference between the mean increase in peak urinary flow rates in the patients with and without periurethral changes seen either immediately or at 3 months after treatment. No statistically significant correlation was found between the amount of prostatic swelling and the improvement in symptom scores or peak urine flow rates. CONCLUSION: In patients who have had laser prostatectomy, MR imaging shows significant immediate glandular swelling, which may account for the delayed improvement in symptoms reported with this technique. The presence of the periurethral changes immediately after treatment was correlated with a subsequent improvement in symptom scores. After 3 months, no cavity could be seen in the prostate. This may account for the poorer long-term clinical outcome reported with endoscopic laser ablation of the prostate compared with transurethral prostatectomy.

High resolution magnetic resonance imaging of the anal sphincter using an internal coil.

An internal receiver coil was used to obtain high resolution transverse and oblique coronal magnetic resonance images of the anal sphincter in five normal volunteers and five patients. The internal sphincter had a high signal intensity on T1 weighted, T2 weighted, and STIR sequences whereas the conjoined longitudinal muscle and external sphincter had a low signal intensity. The internal sphincter (but not the external sphincter) showed contrast enhancement after administration of intravenous gadopentetate dimeglumine. The oblique coronal plane was particularly useful for showing the thickness and the relations of the external sphincter. Sphincteric abscesses as well as muscle defects, hypertrophy, and atrophy were clearly shown. The coil was well tolerated by most subjects. It has considerable potential for improving the diagnosis of anorectal disease.

Laser ablation of the endometrium: MR appearance during and after treatment and the relation of MR appearance to clinical outcome.

OBJECTIVE: Our objective was to study the appearance of the uterus on MR images obtained during and 3 months after laser ablation of the endometrium and to determine if a correlation exists between the MR imaging findings and the subsequent clinical outcome. The appearance could then be used to guide the application of laser energy during the procedure to optimize the clinical result. SUBJECTS AND METHODS: Eight women 34-55 years old (mean, 42 years old) with symptoms of heavy, painful menses underwent laser ablation under epidural anesthesia. Imaging was done on a 0.5-T Picker Asset system with a pelvic phased-array receiver coil using conventional T1-weighted spin-echo, T2-weighted spin-echo, and gradient-recalled-echo sequences. Images were obtained preoperatively, after ablation of the anterior surface, after completion of the procedure, and 3 months later. Images were visually assessed for signal intensity changes in the endometrium and myometrium by two observers in conference. Images were quantitatively analyzed by measuring uterine volume and the width of the endometrium, junctional zone (JZ), and outer myometrium (OM) on the T2-weighted images. Preoperative and 3-month postoperative symptom scores including duration, amount of bleeding, and associated pain were recorded. RESULTS: MR images obtained immediately after treatment showed an increase in the volume of the uterus (mean, 21%). Endometrial thickness increased in five patients, and the JZ:OM ratio increased on the T2-weighted scans in six patients. The increase in the ratio probably represented myometrial edema. Two patients with persistent symptoms were treated with hysterectomy 6 weeks postoperatively. Of the remaining six patients, five showed an improvement in symptom scores after 3 months. The uterus returned to its preoperative size after 3 months in three patients, endometrial thinning was noted in two, and the JZ:OM ratio remained increased in two. The difference between the mean improvement in symptom scores at 3 months was significant in the patients with and without the endometrial swelling seen immediately after treatment. No statistically significant correlation existed between the amount of perioperative uterine swelling or the increase in JZ:OM ratio and the improvement in symptom scores at 3 months. CONCLUSION: On laser ablation of the endometrium, MR imaging showed significant immediate uterine swelling as well as an increase in the endometrial thickness and JZ:OM ratio. The presence of immediate endometrial swelling and the reduction in the JZ:OM ratio after 3 months correlated with a subsequent improvement in symptom scores. Perioperative endometrial swelling rather than myometrial changes is therefore an indicator of clinical outcome.