Sedation of children undergoing magnetic resonance imaging

Editor—We were interested to read the correspondence betweenAllen¹ and Sury and colleagues² on paediatric sedation, havingreported a series in 1999. Changes in our sedation regime³ wereintroduced in 2000. We have since tracked our results for sedationto facilitate MRI scanning in children. In the last five yearsfrom 2002 to 2006, we have performed 4165 sedations and 478general anaesthetics for MRI scan (the general anaesthesia groupbeing     

Sedation of children undergoing magnetic resonance imaging

Editor—As a consultant anaesthetist with a regular ‘paediatricMRI under anaesthesia’ list, I read the paper by Suryand Fairweather¹ with great interest. I use a sevoflurane inhalationinduction followed by i.v. cannulation. A laryngeal mask airway     

Magnetic resonance imaging and magnetic resonance spectroscopic imaging of prostate cancer

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) are evolving techniques that offer noninvasive evaluation of anatomic and metabolic features of prostate cancer. The ability of MRI to determine the location and extent of the tumor and to identify metastatic spread is useful in the pretreatment setting, enabling treatment decision-making that is evidence-based. MRSI of the prostate gland expands the diagnostic assessment of prostate cancer through the detection of cellular metabolites, and can lead to noninvasive differentiation of cancer from healthy tissue. MRI/MRSI can also be used to evaluate both local and systemic recurrence, with endorectal MRI being capable of detecting local recurrence, even in patients with rising serum PSA level but no palpable tumor on digital rectal examination. Considering the benefits that MRI and MRSI have been shown to offer patients, the skills and technology required to perform these tests should be widely disseminated to make their routine use possible. Teamwork between members of radiology, pathology, urology and radiation oncology departments is essential in order to exploit these technologies fully.     

Nuclear magnetic resonance imaging of the prostate

Nuclear magnetic resonance (NMR) imaging of the prostate has been done in 25 patients, using a prototype machine developed in Aberdeen. It is a non-invasive technique which demonstrated the anatomical extent and pathological nature of prostatic lesions. The NMR images in both benign and malignant prostatic disease on this machine are comparable with first generation CT scans.     

Safety of metallic surgical clips in patients undergoing high-field-strength magnetic resonance imaging

Use of metallic clips with ferromagnetic properties in patients undergoing a large variety of surgical procedures, and in particular, in coronary artery and other vascular reconstructions, has become increasingly popular. The safety of these commonly used surgical clips when subjected to high-intensity diagnostic magnetic resonance imaging fields is still debated. Commonly used hemostatic metallic clips manufactured by the Weck and US Surgical Corporations were tested in an in vitro system to assess their safety with regard to migration and displacement. The two tested hemostatic metallic clips proved safe and did not migrate or become dislodged when they underwent magnetic resonance imaging scans. This is in direct contrast to multiple cerebral aneurysm clips, also tested, which have highly ferromagnetic properties and were previously shown to migrate with disastrous results in patients undergoing diagnostic magnetic resonance imaging scans. This study supports the continued widespread use of small metallic hemostatic clips in the myriad of procedures in which they are presently used and illustrates the need for methods of evaluating such devices before they are clinically implanted.     

Endorectal magnetic resonance imaging staging of prostate cancer

BACKGROUND: There are important treatment and prognostic implications in distinguishing between organ-confined prostate cancer that has spread locally outside the capsule and that which has spread into the seminal vesicles. This study is the first Australian study to report local accuracy for the locoregional staging of prostate cancer with endorectal magnetic resonance imaging (MRI). METHODS: From July 2002 to December 2005, 129 patients were referred for endorectal MRI for all indications. Inclusion criteria were biopsy-proven prostate cancer, minimum 4 weeks from previous biopsy and radical retropubic prostatectomy within 12 months of MRI. This yielded 47 patients. Those with prior hormonal and neoadjuvant radiotherapy or significant postbiopsy haemorrhage were excluded. In addition, those patients examined with our alternate-contrast-enhanced protocol were also excluded. A total of 38 patients met all inclusion criteria. A General Electric 1.5-T whole-body MR imaging unit with an endorectal coil was used with interpretation by two genito-urinary MR radiologists. Final histopathological report was used for correlation. RESULTS: Median age was 60 years with a range 44-72 years. Median prostate-specific antigen was 6.3 with a range of 2-82, and median Gleason score was 6 with a range of 5-8. Sensitivity, specificity and accuracy for extracapsular extension and seminal vesicle invasion were 69, 82 and 76% and 60, 100 and 95%, respectively. For extraprostatic extension, 71, 86 and 79%, respectively. CONCLUSIONS: Staging accuracy is similar to internationally published standards. Improvements in hardware and software and increased reader experience will add value to the local Australian prostate imaging programme.     

Serial prostate magnetic resonance imaging fails to predict pathological progression in patients on active surveillance

IntroductionLimited data guide urological practice when employing prostate magnetic resonance imaging (MRI) in active surveillance (AS) protocols. To determine the ability of prostate MRI to predict pathological progression in AS patients, we correlated findings of serial MRI with results of surveillance biopsies.MethodsPatients on AS with ≥2 prostate MRI and ≥2 prostate biopsies were included. Prostate Imaging-Reporting and Data System (PI-RADS) score upgrade, as assigned by experienced radiologists, was used to assess the ability of imaging to predict pathological biopsy progression. Imaging test statistics and the odds ratio of pathological progression according to MRI upgrade were calculated.ResultsOf 121 patients meeting criteria, 36 (30%) demonstrated MRI upgrade. Biopsy progression was noted in 55 patients (46%). Of these, 20 patients (37%) had biopsy progression predicted by MRI upgrade, while the remaining (n=35) had no lesion upgrade on prostate MRI. Conversely, among those with no biopsy progression (n=66), 16 patients (24%) had a false-positive upgrade on serial MRI. We report a sensitivity and specificity of MRI change for pathological progression of 36% and 76%, respectively. Although MRI change was associated with a positive predictive value of 56% for pathological progression, patients with a high-suspicion lesion (PI-RADS >3) at any time were more likely to experience disease progression, (odds ratio 3.3, 95% confidence interval 1.6–8.0, p<0.01).ConclusionsGiven its modest sensitivity/specificity, serial prostate MRI should be used judiciously as a surveillance tool. However, when prostate MRI demonstrates a PI-RADS >3 lesion, a high index of suspicion should be maintained, as these patients are more likely to progress on AS.     

前列腺电切术后MRS的随访研究

目的:采用MRS随访前列腺电切术后特征代谢物变化。方法:收集10例前列腺电切术后患者,其中5例前列腺增生,5例前列腺癌,应用MRS分析代谢物不同。结果:前列腺增生可有明显枸橼酸盐峰增高,前列腺癌有明显胆碱峰增高,两者特征代谢物有明显差异。结论:MRS能特异、便捷的了解前列腺电切术后的前列腺疾病复发,进展情况。     

Combined propofol and remifentanil intravenous anesthesia for pediatric patients undergoing magnetic resonance imaging

BACKGROUND: A prospective observational case series of children receiving light general anesthesia for magnetic resonance imaging (MRI) was performed. Our purpose was to examine the merit of anesthesia and recovery/discharge times of combined remifentanil and propofol total intravenous anesthesia (TIVA) in spontaneously breathing children. METHODS: After IRB approval and informed consent, 56 patients receiving Remi/Propofol TIVA (Remifentanil 10 microg.ml(-1) Propofol 10 mg.ml(-1)) were observed. Blood pressure, respiratory rate, endtidal CO(2) (P(E)CO(2)), oxygen saturation and temperature were recorded at the start and finish of anesthesia. In addition, induction and recovery times were noted. Recovery time was from scan completion until discharge from the initial recovery area. Discharge time was from scan completion to discharge home. RESULTS: Fifty-six patients received Remi/Propofol TIVA. The mean Remi/Propofol recovery and discharge times were 8.9 and 28.2 min, respectively. There was a statistically significant decrease in respiratory rate and increase in CO(2) from the start to the end of the procedure. During the scan, seven patients moved. One patient experienced postprocedure nausea and or vomiting. CONCLUSIONS: The combination of remifentanil and propofol for TIVA may be an effective method of light general anesthesia in pediatric patients undergoing MRI.     

Role of magnetic resonance imaging and magnetic resonance spectroscopic imaging before and after radiotherapy for prostate cancer

PURPOSE: To describe the practical technical aspects of magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) and to summarize the current and potential future status of MRI and MRSI in the localization, staging, treatment planning, and post-treatment follow-up of prostate cancer. TECHNIQUE: Published contemporary series of patients with prostate cancer evaluated by MRI and MRSI before or after radiation therapy were reviewed, with particular respect to the role of MRI and MRSI in treatment planning, outcome prediction, and detecting local recurrence. RESULTS: Volumetric localization is of limited accuracy for tumors less than 0.5 cm(3). Staging by MRI, which is improved by the addition of MRSI, is of incremental prognostic significance in patients with moderate and high-risk tumors. The finding of more than 5 mm of extracapsular extension prior to radiation seems to be of particular negative prognostic significance, and the latter group may be candidates for more aggressive supplemental therapy. The use of MRI to assist radiation treatment planning has been shown to improve outcome. MRSI may be helpful in the detection of local recurrence after radiation. CONCLUSIONS: Only MRI and MRSI allow combined structural and metabolic evaluation of prostate cancer location, aggressiveness, and stage. Combined MRI and MRSI provide clinically and therapeutically relevant information that may assist in planning and post-treatment monitoring in patients undergoing radiation therapy.     

Value of magnetic resonance imaging in prostate cancer diagnosis

MRI has shown its potential in prostate cancer (PCa) imaging. MRI is able to demonstrate zonal anatomy with excellent contrast resolution. Furthermore it can detect PCa dependent not only on tumor-size, histological grading, PSA levels, but also on technical equipment and reader’s experience. Non-palpable PCas in the inner and outer gland can be detected by this technique. Another potential is that MRI is helpful for tumor staging and treatment planning as well as response evaluation. Besides the morphological information, MRI can give functional information based on metabolic evaluation with proton magnetic resonance spectroscopy and of tumor angiogenesis based on dynamic contrast-material enhanced MRI and diffusion-weighted imaging. In addition MRI can be used for targeted prostate biopsies; however, the clinical practicability is questionable. Furthermore many data about the value of MRI for PCa diagnosis are based on transrectal ultrasound (TRUS) biopsy findings. Since there is lack of accuracy in fusing MRI images with TRUS images these limit the results of MRI for cancer diagnosis. However, in the future MRI may play an additional role in planning and monitoring minimally invasive PCa therapies. Although, MRI of the prostate seems to be useful, nevertheless this method remains expensive and lacks availability regarding the oncoming requirements.     

Accuracy of preoperative multiparametric magnetic resonance imaging for prediction of unfavorable pathology in patients with localized prostate cancer undergoing radical prostatectomy

Introduction

We investigated the accuracy of multiparametric MRI (mpMRI) for preoperative staging and its influence on the determination of neurovascular bundle sparing and disease prognosis in patients with localized prostate cancer.

Methods

We reviewed 1045 patients who underwent radical prostatectomy with preoperative mpMRI at a single institution. Clinical local stages determined from mpMRI were correlated with preoperative and postoperative pathological outcomes.

Results

The sensitivity and specificity to diagnose seminal vesicle invasion (SVI) on mpMRI were 43.8 and 95.4 %, respectively. The negative predictive value was 78.9 %. The sensitivity and specificity to diagnose extracapsular extension (ECE) were 54.5 and 80.5 %, respectively. The overall sensitivity and specificity of diagnosing pathological T3 or higher were 52.6 and 82.1 %, respectively. Non-organ-confined disease determined by mpMRI was significantly associated with positive surgical margin and pathological T3 disease on multivariate analysis. Preoperative adverse findings on mpMRI were significantly associated with performance of the non-nerve-sparing technique.

Conclusion

mpMRI did not show outstanding diagnostic accuracy relative to our expectations in predicting SVI or ECE preoperatively. However, adverse findings on preoperative mpMRI were significantly related to worse postoperative pathological outcomes as well as postoperative biochemical recurrence.

     

Patient selection for magnetic resonance imaging of prostate cancer.

BACKGROUND: Routine magnetic resonance (MR) imaging for local staging of prostate cancer is controversial, due to moderate staging performance. However, MR imaging may be beneficial in a subgroup of patients with clinically localized prostate cancer. OBJECTIVE: To define the patient group in which local staging of prostate cancer using MR imaging is useful for treatment outcome. METHODS: We used a decision analytic model based on data found in the literature to define the patient subgroup which may benefit from local staging with MR imaging. We applied the threshold approach to calculate the threshold where direct surgery and surgery after MR imaging (surgery-MR imaging threshold) result in equal utility. Additionally, we calculated the threshold where direct radiation and radiation after MR imaging (MR imaging-radiotherapy threshold) result in equal utility. RESULTS: We found that the surgery-MR imaging threshold was at a probability of 45% of having stage > or =T(3) disease. The MR imaging-radiotherapy threshold was at a prior probability of 81% of having stage > or =T(3) disease. CONCLUSIONS: The application of the threshold approach indicated that MR imaging should be limited to patients with an intermediate-high risk of having stage T(3) disease.     

Clinical utility of diffusion-weighted magnetic resonance imaging in prostate cancer

Study Type – Diagnostic (exploratory cohort) Level of Evidence 2b What’s known on the subject? and What does the study add? This article reviews what is currently known about diffusion weighted MRI (DW‐MRI) in prostate cancer. This mini‐review concisely summarises, for clinical managing patients with prostate cancer, the clinical utility of diffusion weighted MRI.

OBJECTIVE

? To review the clinical utility of diffusion‐weighted magnetic resonance imaging (DW‐MRI) in patients with prostate cancer.

MATERIAL AND METHODS

? The current literature on prostate cancer and DW‐MRI was reviewed.

RESULTS

? DW‐MRI can be readily acquired on a modern scanner with a short image acquisition time and no need for i.v. contrast medium. ? The image contrast is based on the diffusion of water molecules and thus reflects tissue cellularity. ? There is increasing evidence that DW‐ MRI improves the sensitivity and specificity of prostate cancer detection as well as the identification of tumour aggressiveness. ? DW‐MRI is also showing substantial promise as a response biomarker for both local and metastatic disease

CONCLUSIONS

? DW‐MRI is proving to be a useful adjunct to conventional T2‐weighted MRI sequences. ? The eventual role of DW‐MRI in combination with other MRI techniques for multiparametric assessment of prostate cancer needs to be defined further.     

Anesthesiologic assistance to children undergoing magnetic resonance

The paper describes the anesthesiological technique used during magnetic resonance tomography in young patients. The Authors developed a neurosedative technique, based on the balanced use of thiopentone sodium, DBP and atropine, which was used in a large study involving 247 patients between November 1986 and April 1989. The results were found to be excellent in patients treated under day hospital conditions, and the Authors conclude that this method is the most efficacious of all solution tested in pediatric patients undergoing magnetic resonance tomography.