胰腺内分泌肿瘤磁共振影像学特征

胰腺内分泌肿瘤是一种少见肿瘤,分为功能性和无功能性两大类,临床表现各异,容易漏诊和误诊.随着MRI技术的发展,特别是脂肪抑制技术、弥散加权成像扫描(DWI)及动态增强MRI扫描的应用,对胰腺内分泌肿瘤的影像学诊断及鉴别诊断具有重要价值.本研究回顾性分析2007年6月至2011年12月湖北省恩施土家族苗族自治州中心医院收治的13例胰腺内分泌肿瘤患者的临床资料,旨在总结该病的MRI检查表现特征,评价MRI检查特别是DWI和动态增强扫描对胰腺内分泌肿瘤的诊断价值.     

Standing open magnetic resonance imaging improves detection and staging of pelvic organ prolapse

IntroductionThe role of imaging in pelvic organ prolapse (POP) assessment is unclear. Open magnetic resonance imaging (MRI) systems have a configuration that allows for imaging women with POP in different positions. Herein, we use a 0.5 Tesla open MRI to obtain supine, seated, and standing images. We then compare these images to evaluate the impact of posture on detection and staging of POP.MethodsWomen presenting with symptoms of POP at a tertiary care university hospital were asked to participate in this prospective cohort study. Symptom scores, POP-Q staging and three-position MRI imaging of the pelvis data were collected. The pubococcygeal line (PCL) was used to quantify within-patient changes in pelvic organ position as defined by: no displacement, <1 cm inferior to the PCL, mild (1–3 cm), moderate (3.1–6 cm), and severe (>6 cm) in the axial and sagittal T2-weighted images. Statistical analysis was completed (T-test; p<0.05 significant).ResultsA total of 42 women, age range 40–78 years, participated. There was a significant difference in the mean values associated with anterior prolapse in the supine (0.7±1.8), seated (2.4±3.4), and upright (4.2±1.6) positions (p=0.015). There was a significant difference in the mean values associated with apical prolapse in the supine (0.5±1.5), seated (1.5±1.4), and upright (2.1±1.5) positions (p=0.036).ConclusionsOur findings suggest that POP is more readily detected and upstaged with standing MRI images as compared to supine and seated positions. The developed two-minute standing MRI protocol may enable clinicians to better assess the extent of POP.     

Computed tomography and nuclear magnetic resonance imaging of pancreatic islet cell tumors

Eleven patients with pancreatic islet cell tumors smaller than 2.5 cm were examined by use of computed tomography (CT) and new scanning protocol. Seven of 11 tumors were localized and CT accurately assessed multiple lesions, retroperitoneal invasion, or liver metastases when present. CT is now the initial imaging procedure of choice for diagnosis and staging of islet cell tumors. Nuclear magnetic resonance can distinguish islet cell tumors from normal retroperitoneal structures and appears to be a promising new pancreatic imaging modality.     

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.     

Breast magnetic resonance imaging for preoperative locoregional staging

BACKGROUND: Breast magnetic resonance imaging (MRI) has been recommended increasingly in the preoperative setting for patients newly diagnosed with malignancy to evaluate tumor extent, multicentricity, and contralateral disease. METHODS: Results of conventional imaging, breast MRI, and pathology were analyzed from 603 consecutive breast cancer patients who underwent MRI preoperatively. The focus of this retrospective study was imaging-histologic correlation. RESULTS: Reoperation for positive margins after lumpectomy occurred in 8.8% of patients. Multicentricity was identified by MRI alone in 7.7% of patients, whereas 3.7% were found to have contralateral cancer by MRI. The sensitivity of MRI was 93% in detecting multicentric disease and 88% for contralateral disease, whereas sensitivity for conventional imaging was 46% and 19%, respectively. Unsuspected disease was identified by MRI equally for invasive ductal and ductal carcinoma in situ histology, whereas multicentricity was found more frequently with invasive lobular carcinoma. CONCLUSIONS: Breast MRI is recommended for preoperative evaluation of the newly diagnosed breast cancer patient.     

Differential diagnosis and staging of urological tumors by magnetic resonance imaging compared with computed tomography

Magnetic resonance imaging (MRI) was performed on 49 urological tumors (11 renal cell carcinomas, 3 renal pelvic cancers, 2 renal angiomyolipomas, 1 renal leiomyosarcoma, 1 large renal cyst, 4 adrenal tumors, 11 bladder cancers, 2 bone metastasis from bladder cancer, 10 prostatic cancers, 1 prostatic sarcoma, 1 urethral cancer, 1 penile cancer and 1 perivesical granuloma) since October 1985 to September 1986. MRI was performed using a Signa (G.E.) with a 1.5T superconductive magnet and 3 images, including T1 weighted image, T2 weighted image, and proton density image, were obtained. In conclusion MRI is a noninvasive examination and gives more information than computed tomography despite its high cost. In renal cell carcinoma, the chemical shift in MRI and clear visualization of tumor thrombus enable accurate staging. Differential diagnosis from other renal mass lesions may be possible by the T2 weighted image. In adrenal disease, most of the adrenal masses can be differentiated, but in some cases it is impossible. In bladder cancer, wall invasion of tumor may be evaluated in T2 weighted image, and MRI is suitable for staging of locally advanced tumor. In prostatic cancer, visualization of periprostatic plexus and differentiation between internal and external gland may enable local staging and identification of low stage tumors.     

Gadolinium-enhanced magnetic resonance imaging in the staging of urinary bladder neoplasms

Magnetic resonance imaging (MRI) proved to be an important diagnostic tool in the correct staging of bladder neoplasms. The advantage of multiplane imaging and high soft-tissue contrast may be extended by the use of MRI contrast media such as the gadoliniumdiethylene-triaminepentaacetic acid complex. In 60 patients with suspected or proved bladder tumors, the results of preoperative gadolinium-enhanced MRI were correlated with the histopathologic findings. The staging accuracy of infiltrating tumors was 83% and sensitivity and specificity 86% and 83%, respectively. Three tumors could only be localized after administration of gadolinium. All active tumors demonstrated significant contrast enhancement after intravenously injected gadolinium. Small papillary tumors or carcinoma in situ remain problematic to preoperative staging procedures. The advantages of gadolinium-enhanced MRI will best be employed in the exact pretherapeutic staging of infiltrative bladder neoplasms or in restaging procedures after chemotherapy and radiotherapy.     

Intraoperative magnetic resonance imaging ablation of hepatic tumors

BACKGROUND: The use of hepatic ablation of tumors for both primary and secondary cancers has continued to increase at a significant rate. The most significant increase in the use of hepatic ablation has come from image-guided techniques with computed axial tomography and ultrasound. Limitations to targeting hepatic lesions by these techniques remain morbid obesity, abnormal hepatic parenchyma, and inability to visualize lesions without the use of intravenous contrast. In contrast, magnetic resonance imaging (MRI) has continued to provide a high contrast of soft tissue-to-lesion conspicuity without the need for intravenous dye. The recent development of open-configuration magnetic resonance scanners--which have allowed improved patient access, near real-time imaging, and more available MRI-compatible equipment--has opened up an entire new area of image-guided surgical and interventional procedures. METHODS: The principles and indications for all types of image-guided hepatic ablations are described. RESULTS: The success and limitations of image-guided ablation techniques. CONCLUSIONS: Image-guided hepatic ablation represents a useful technique in managing hepatic tumors. Intraoperative MRI represents a new technique with initial success that has been limited to European centers. Further evaluation in United States centers has demonstrated intraoperative MRI to be useful for certain hepatic tumors that cannot be adequately visualized by ultrasound or computed axial tomography. A multidisciplinary approach involving a surgical oncologist and interventional radiologist remains integral to the short- and long-term success of image-guided ablation.     

Diffusion tensor magnetic resonance imaging of brain tumors

DTI seems to offer the possibility of adding important information to presurgical planning. Although experience is limited, DTI seems to provide useful local information about the structures near the tumor, and this seems to be useful in planning. In the future, DTI may provide an improved way to monitor intraoperative surgical procedures as well as their complications. Furthermore, evaluation of the response to treatment with chemotherapy and radiation therapy might also be possible. Although DTI has some limitations, its active investigation and further study are clearly warranted.     

磁共振成像技术对直肠癌术前分期应用的评价

目的探讨MRI直肠成像技术对直肠癌术前分期的价值。方法2004年12月至2006年6月，156例经肠镜和病理确诊为直肠癌的患者在我院行直肠MRI扫描，将影像诊断结果与手术病理结果进行对照。结果156例患者中72例表现为腔内局限性软组织肿块；84例表现为肠壁不规则增厚．肠腔环形狭窄环绕肠腔1周或部分：16例合并直肠息肉，2例合并卵巢囊肿；骶前转移13例．股骨转移2例。MRI对直肠T1-2、T3和L分期的敏感性分别为25.0％（8／32）、93.3％（84／90）、94．1％（32／34），特异性分别为100％（124／124）、57．6％（38／66）、96．7％（118／122）。MRI对肠旁转移淋巴结诊断（直径超过5mm，边界不规则或呈混合信号定为转移）的敏感性85．1％（80／94）．特异性45．2％（28／62）。结论MRI对直肠癌的术前分期诊断有较高的准确性，有助于判断肿瘤直肠浆膜外浸润及区域淋巴结转移。     

Nuclear magnetic resonance imaging in detecting and staging prostatic cancer

Thirteen patients were examined for grade, stage, and extent of their prostatic cancer, utilizing nuclear magnetic resonance imaging (MRI) and clinical workup for metastases. Of these 13 patients, 12 had known prostatic cancer proved by needle biopsy or by pathologic examination of transurethral prostatectomy tissue. Five of these patients underwent radical surgery allowing further correlation of clinical findings and MRI data with the surgical pathologic findings. MRI of the prostate was found to be a sensitive modality in detecting prostatic carcinoma and showing extension of disease in some cases. Also, in some cases it was not always possible to differentiate between prostatic carcinoma and benign prostatic hyperplasia with MRI.     

The value of magnetic resonance imaging in the staging of musculoskeletal tumours

In view of the changes that are occurring in the management of musculoskeletal tumours and the importance of precise pre-operative staging, a study to determine the value of magnetic resonance imaging (MRI) as a modality for this purpose was undertaken. Sixty-four patients were examined and 70 MRI examinations were carried out. Fifteen cases were found to be benign and 49 malignant. As a result of the accuracy of these MRI examinations and their remarkable similarity with the pathological specimens, which was shown to be statistically significant (P less than 0,005), we propose a modification to the sequence of the diagnostic staging modalities for musculoskeletal tumours.     

The role of magnetic resonance imaging in the staging of bladder carcinoma

The clinical staging of bladder carcinoma traditionally has relied on transurethral resection of the bladder tumor, urinary cytology, excretory urography and an examination with the patient under anesthesia. Recent evidence has shown magnetic resonance imaging to be effective in the staging of bladder cancer. Whether magnetic resonance imaging is more accurate than conventional clinical staging techniques has not been answered. To determine the usefulness of magnetic resonance imaging in this regard 34 patients with bladder carcinoma underwent staging by this technique before radical cystectomy. The magnetic resonance imaging stage and conventional clinical stage were compared to the final pathological stage. Magnetic resonance imaging had an over-all accuracy of 50 per cent versus 57 per cent for conventional staging techniques and it identified 2 of 5 patients with nodal disease. To date magnetic resonance imaging does not appear to be better than conventional clinical staging techniques in patients with bladder carcinoma.     

Is magnetic resonance imaging necessary in the staging of prostate cancer?

OBJECTIVE: To evaluate the necessity of using magnetic resonance imaging (MRI) in the staging of patients with clinically localized prostate cancer. METHODS: Sixty-one patients with prostate cancer were evaluated with MRI for preoperative staging with a conventional body-coil (Siemens Magnetom, 1.0 Tesla superconducting system). Twenty-nine patients underwent radical prostatectomy for presumed clinically localized disease. Of those, 17 were staged both with MRI and computerized tomography (CT). The remaining patients were staged with CT alone. MRI and CT findings, and the final pathologic staging of patients are reviewed. RESULTS: On pathological examination of the surgical specimens, the tumor was found to extend beyond the prostate in 7 patients (41%). Among the 17 patients who were operated, extraprostatic extension (EPE) was detected accurately in 3 patients with MRI (sensitivity 20%, specificity 92%, accuracy 70. 5%). No metastatic lymph nodes were detected on the basis of MRI (sensitivity 0%, specificity 93%, accuracy 88.2%). In 1 patient EPE was correctly identified by CT (sensitivity 14%, specificity 100%, accuracy 64.7%). CONCLUSION: Neither MRI with conventional body-coild nor CT are sufficient to indicate local extension of disease in clinically localized prostate cancer.     

Intraoperative magnetic resonance imaging for ablation of hepatic tumors

BACKGROUND: The most significant rise in the use of hepatic ablation has come from image-guided techniques with both computed tomography (CT) and ultrasound (US). The recent development of open-configuration magnetic resonance scanners has opened up an entire new area of image-guided surgical and interventional procedures. Thus the aim of this study was to evaluate the use of intraoperative MRI (iMRI) ablation of hepatic tumors performed by surgeons. METHOD: Percutaneous iMRI hepatic ablation was performed from January 2003 to February 2005 for control of either primary or secondary hepatic disease. RESULTS: Eighteen hepatic ablations were performed on 11 patients with a median age of 71 (range: 51-81) years for metastatic colorectal cancer (n = 6), hepatocellular cancer (n = 2), cholangiocarcinoma (n = 2), and metastatic neuroendocrine (n = 1). Median hospital stay was 1 day, with complications occurring in 2 patients. After a median follow up of 18 months, there have been no local ablation recurrences, 5 patients are free of disease, 4 are alive with disease, 1 has died of disease, and 1 has died of other causes. CONCLUSIONS: Image-guided hepatic ablations represent a useful technique in managing hepatic tumors. Intraoperative MRI represents a new technique with initial success that has been limited to European centers. Further evaluation in U.S. centers has demonstrated iMRI to be useful for certain hepatic tumors that cannot be adequately visualized by US or CT.     

The role of magnetic resonance imaging in the local staging of penile cancer

OBJECTIVES: To assess the accuracy of magnetic resonance imaging (MRI) as a local staging technique in penile cancer and its role in selecting patients for conservative surgical management. METHODS: Fifty-five men diagnosed with invasive penile carcinoma on biopsy were locally staged with the use of MRI. Prostaglandin E1 (alprostadil) was injected into the corpora to induce an artificial erection. Radiologic staging was compared against final histopathologic stage of the tumour. Sensitivity, specificity, and kappa agreement values were calculated for each tumour stage. Additionally, corpora cavernosa involvement was reviewed in 20 consecutive cases and suitability for conservative surgery assessed. RESULTS: A good correlation between radiologic and histologic staging was achieved with an overall kappa value of 0.75 (p<0.001). Stage-specific sensitivities and specificities were calculated: T1 (85%; 83%), T2 (75%; 89%), and T3 (88%; 98%). MRI accurately predicted corpora cavernosa invasion in all cases of pathologically proven disease. These patients were selected to undergo partial penectomy. There were no complications using this imaging technique. CONCLUSIONS: This study demonstrates that penile MRI is highly accurate in the local staging of penile cancer. Associated improvements in surgical planning allow the provision of conservative surgical treatments over more radical procedures.     

High-resolution magnetic resonance imaging quantitatively detects individual pancreatic islets

OBJECTIVE

We studied whether manganese-enhanced high-field magnetic resonance (MR) imaging (MEHFMRI) could quantitatively detect individual islets in situ and in vivo and evaluate changes in a model of experimental diabetes.

RESEARCH DESIGN AND METHODS

Whole pancreata from untreated (n = 3), MnCl₂ and glucose-injected mice (n = 6), and mice injected with either streptozotocin (STZ; n = 4) or citrate buffer (n = 4) were imaged ex vivo for unambiguous evaluation of islets. Exteriorized pancreata of MnCl₂ and glucose-injected mice (n = 6) were imaged in vivo to directly visualize the gland and minimize movements. In all cases, MR images were acquired in a 14.1 Tesla scanner and correlated with the corresponding (immuno)histological sections.

RESULTS

In ex vivo experiments, MEHFMRI distinguished different pancreatic tissues and evaluated the relative abundance of islets in the pancreata of normoglycemic mice. MEHFMRI also detected a significant decrease in the numerical and volume density of islets in STZ-injected mice. However, in the latter measurements the loss of β-cells was undervalued under the conditions tested. The experiments on the externalized pancreata confirmed that MEHFMRI could visualize native individual islets in living, anesthetized mice.

CONCLUSIONS

Data show that MEHFMRI quantitatively visualizes individual islets in the intact mouse pancreas, both ex vivo and in vivo.Despite the high incidence of diabetes, the precise molecular and cellular mechanisms that cause the decrease in the mass and function of the insulin-producing β-cells, observed in both the type 1 and type 2 forms of the disease, remain to be elucidated (1). At present, the only, although somewhat indirect, way to monitor the onset and the evolution of the diseases in a given individual is by using sensitive immunological and functional tests, which require injections and repeated blood sampling. However, we still lack a method that could visualize and quantitate pancreatic β-cells in vivo, in a fully noninvasive way. As a result, we also lack a solid biological basis to target new therapeutic approaches that could promote the regeneration (type 1 diabetes) or the function (type 2 diabetes) of β-cells. The difficulty in imaging these cells stems from their deep abdominal location, their distribution in small (50–600 μm in diameter) islets of Langerhans, their modest volume density (∼1%) in a control pancreas, and their close relationships to different cell types of both endocrine and exocrine nature.Several of these issues have been partially solved using optical methods, which can now investigate laboratory rodents (2–4), but which cannot be adapted to human studies, given the limited tissue penetration of light (2,4–6). Penetration is not an issue in magnetic resonance (MR) imaging (MRI) and positron-emitting tomography (PET) imaging, which are convenient for human applications, specifically if combined with computed tomography. Because islets are structurally and functionally heterogeneous, and are not all simultaneously altered to the same degree during diabetes development, their individual visualization is important. The choice of an imaging modality is then restricted to MRI, given that the lateral resolution of PET is, at best, in the millimeter range (7). MRI has already been used to visualize transplanted islets (8–11), but has not yet been shown to detect native islets in situ, mostly because of an insufficient spatial resolution, which is only provided by the use of a high magnetic field (8,12–14).The aim of the current study was to investigate whether imaging of individual islets could be achieved using a 14.1 Tesla (T) MR scanner. In the absence of a validated probe for the specific staining of β-cells, we have also tested whether the MRI contrast of these islets could be enhanced by an in vivo infusion of manganese (12). Our data document that the combination of these conditions, in manganese-enhanced high-field magnetic resonance imaging (MEHFMRI), allows for the easy differentiation of multiple tissues within the whole murine pancreas, including individual islets of Langerhans. The approach quantitatively detects the loss of pancreatic islets in an animal model of type 1 diabetes, and with this approach pancreatic islets in the living animal can be investigated.     

卵巢肿瘤的核磁共振成像诊断分析

目的：探讨核磁共振成像（MRI）在卵巢肿瘤临床中诊断价值。方法收集84例卵巢肿瘤患者作为研究对象,随机分为研究组与对照组42例,研究组给予 MRI 诊断,对照组给予 B 超诊断,观察两组诊断的准确性、特异性及敏感性。结果研究组患者诊断的准确性、特异性及敏感性均优于对照组,差异有统计意义（P ＜0.05）;研究组对卵巢肿瘤的定性要优于对照组,差异有统计意义（P ＜0.05）。结论在卵巢肿瘤中采用 MRI 诊断,其诊断的准确性、特异性及敏感性都比较高,且能对肿瘤准确定性,值得推广。