Complex US adnexal masses during pregnancy: Is pelvic MR imaging accurate for characterization?

ObjectiveTo retrospectively evaluate the accuracy of pelvic magnetic resonance (MR) imaging for the characterization of complex sonographic adnexal masses discovered in women during pregnancy.Study designThe study population comprised 31 pregnant women (median age: 32 years (range: 19–42); mean gestation age of 16 weeks) referred to our institution for MR imaging for characterization of an adnexal mass discovered incidentally during routine ultrasound (US) for other indications. The population comprised of 31 women, with 36 adnexal lesions (mean size: 103 mm [range: 20–290]), of which 27 were benign and 9 were malignant masses. Prospective US and MR reports were reviewed to determine the presence of a benign or malignant lesion. Two radiologists (R1 and R2) blinded to the final outcome, retrospectively evaluated the MR images using the criteria based on the A_DNEXMR-S_CORE and classified the lesion as benign or malignant. The reference standard was surgical pathology or at least a 1-year imaging follow-up.ResultsProspective US and MR imaging correctly identified the diagnosis in 27/36 (75%) (95% confidence interval (CI): 58.9%–86.2%) and in 32/36 (88.9%) (95% CI: 74.6%–95.6%) of lesions, respectively. MR imaging with A_DNEXMR-S_CORE allowed a correct diagnosis in 32/36 (88.9%) (95% CI: 74.6%–95.6%) of lesions for R1 and in 30/36 (83.3%) (95% CI: 68.1%–92.1%) of lesions for R2. The sensitivities and specificities of MR imaging using the MR A_DNEXMR-S_CORE were 100% (95% CI: 70.1%–1000%) for both readers and 85.1% (95% CI: 67.5%–94%) and 77.7% (95% CI: 59.2%–89.4%) for R1 and R2, respectively. No malignancy was classified as benign using MR criteria. The reproducibility between the two readers was almost perfect, with a kappa of 0.914.ConclusionMR imaging is highly accurate for the characterization of complex adnexal masses incidentally discovered during pregnancy.Clinical relevanceMR imaging can accurately characterize adnexal masses in pregnancy and could be useful in opting for expectant management until delivery.     

How long the lymphoscintigraphy imaging should be continued for sentinel lymph node mapping?

Objective  We assessed the need for delayed lymphoscintigraphy imaging for sentinel lymph node (SLN) biopsy in stage I and II breast cancer patients using intradermal injection of ^99mTc-antimony sulfide colloid. Method  Seventy-five patients with early-stage breast cancer were included in our study. Periareolar intradermal injections of 0.5 mCi/0.2 mL ^99mTc-antimony sulfide colloid was used for the patients without previous excisional biopsy (45 patients). Two intradermal injection of 0.5 mCi/0.2 mL ^99mTc-antimony sulfide colloid was used on each side of the dermal incision in patients with the history of excisional biopsy (30 patients). Anterior and lateral static images were taken at 2 min. If SLN was not visualized, delayed imaging at 5, 10, 30, 60, 90, 150, and 180 min was done (till the visualization of the SLN or 180 min). SLN was performed by the combination of gamma probe and blue dye during surgery. Results  Sentinel lymph node detection rate was 96% (72/75). SLNs were detected on the immediate (2 min) images in 55 (73.33%) patients. In the remaining patients, the SLNs were detected first on the 5-, 10-, and 30-min images in 10 (13/33%), 5 (6.66%), and 2 (2.66%) patients, respectively. In three patients (4%), SLN was not detected by lymphoscintigraphy even on 180-min images. During surgery, SLN was not detected in these three patients either. Conclusion  Considering the rapid flow of ^99mTc-antimony sulfide colloid in our study, lymphoscintigraphy imaging can be completed in the nuclear medicine department without any delay in sending the patient back to the surgery department. Thirty minutes after radiotracer injection seems to be the optimal time for lymphoscintigraphy and delayed imaging beyond 30 min would not be necessary.     

Can contrast-enhanced MR imaging predict survival in breast cancer?

Purpose: 
To investigate the value of pre-operative contrast-enhanced MR imaging (CE-MRI) in predicting the disease-free and overall survival in breast cancer. Material and Methods: 
The study population consisted of 50 consecutive patients with histopathologically verified primary breast cancer who pre-operatively underwent CE-MRI examination between 1992 and 1993. A three-time point MR examination was performed where the enhancement rates (C₁ and C₂), signal enhancement ratio (SER = C₁/C₂) and washout (W = C₁-C₂) were calculated. The relation of these MR parameters to disease-free and overall survival was investigated. The median follow-up for surviving patients was 95 months. Univariate and multivariate statistical analyses were performed to evaluate the impact of different factors on prediction of survival. Results: 
Of the MR parameters examined at univariate analysis, increased C₁ (p = 0.029), W (p = 0.0081) and SER values (p = 0.0081) were significantly associated with shorter disease-free survival, and only C₁ (p = 0.016) was related significantly to overall survival. Multivariate analysis for disease-free survival showed that the SER (p = 0.014) and tumor size (p = 0.001) were significant and independent predictors. Age (p = 0.003), lymph node status (p = 0.014), tumor size (p = 0.039) and proliferating cell nuclear antigen index (p = 0.053) remained independently associated with overall survival at multivariate analysis. C₁ was not confirmed as an independent predictor of overall survival. Conclusion: 
Our findings support the presumption that CE-MRI is useful in predicting the disease-free survival in patients with breast cancer.     

Can pre-operative contrast-enhanced dynamic MR imaging for prostate cancer predict microvessel density in prostatectomy specimens?

The aim of this study was to correlate quantitative dynamic contrast-enhanced MRI (DCE MRI) parameters with microvessel density (MVD) in prostate carcinoma. Twenty-eight patients with biopsy-proven prostate carcinoma were examined by endorectal MRI including multiplanar T2- and T1-weighted spin-echo and dynamic T1-weighted turbo-FLASH MRI during and after intravenous Gd-DTPA administration. Microvessels were stained on surgical specimens using a CD31 monoclonal antibody. The MVD was quantified in hot spots by counting (MVC) and determining the area fraction by morphometry (MVAF). The DCE MRI data were analyzed using an open pharmacokinetic two-compartment model. In corresponding anatomic locations the time shift (t) between the beginning of signal enhancement of cancer and adjacent normal prostatic tissue, the degree of contrast enhancement and the contrast exchange rate constant (k₂₁) were calculated. The MVC and MVAF were elevated in carcinoma (p<0.001 and p=0.002, respectively) and correlated to k₂₁ (r=0.62, p<0.001 and r=0.80, p<0.001, respectively). k₂₁-values of carcinoma were significantly higher compared with normal peripheral but not central zone tissue. t was longer in high compared with low-grade tumors (p=0.025). The DCE MRI can provide important information about individual MVD in prostate cancer, which may be helpful for guiding biopsy and assessing individual prognosis.     

Pneumobilia: where to look for on hepatic MR imaging?

The presence of pneumobilia is a particular problem in magnetic resonance cholangiopancreatography (MRPC) and may create an appearance that can be mistaken for intraductal stones. Compared with biliary stones, however, pneumobilia causes a susceptibility artifact on hepatic MR imaging and appears as a signal void on a dual echo gradient MR sequence, such as the T1-weighted in-phase and opposed-phase gradient echo sequence. This susceptibility artifact is more pronounced on the gradient echo image with the longer echo time due to the continued decay of the transverse magnetization. Besides identification of hepatic steatosis, the double echo approach is particularly helpful in identification of pneumobilia.     

Positional MR imaging of the lumbar spine: does it demonstrate nerve root compromise not visible at conventional MR imaging?

PURPOSE: To evaluate whether positional magnetic resonance (MR) images of the lumbar spine demonstrate nerve root compromise not visible on MR images obtained with the patient in a supine position (conventional MR images). MATERIALS AND METHODS: Thirty patients with chronic low back pain unresponsive to nonsurgical treatment and with disk abnormalities but without compression of neural structures were included. Positional MR images were obtained by using an open-configuration, 0.5-T MR imager with the patients seated and with flexion and extension of their backs. The disk and nerve root were related to the body position. Nerve root compression and foraminal size were correlated with the patient's symptoms, as assessed with a visual analogue scale. RESULTS: Nerve root contact without deviation was present in 34 of 152 instances in the supine position, in 62 instances in the seated flexion position, and in 45 instances in the seated extension position. As compared with the supine position, in the seated flexion position nerve root deviation decreased from 10 to eight instances; in the seated extension position, it increased from 10 to 13 instances. Nerve root compression was seen in one patient in the seated extension position. Positional pain score differences were significantly related to changes in foraminal size (P =.046) but not to differences in nerve root compromise. CONCLUSION: Positional MR imaging more frequently demonstrates minor neural compromise than does conventional MR imaging. Positional pain differences are related to position-dependent changes in foraminal size.     

Breast imaging. Preoperative breast cancer staging: comparison of USPIO-enhanced MR imaging and 18F-fluorodeoxyglucose (FDC) positron emission tomography (PET) imaging for axillary lymph node staging—initial findings

Magnetic resonance (MR) imaging after ultra-small super paramagnetic iron oxide (USPIO) injection and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) for preoperative axillary lymph node staging in patients with breast cancer were evaluated using histopathologic findings as the reference standard. USPIO-enhanced MR and FDG-PET were performed in ten patients with breast cancer who were scheduled for surgery and axillary node resection. T2-weighted fast spin echo, T1-weighted three-dimensional (3D) gradient echo, T2*-weighted gradient echo and gadolinium-enhanced T1-weighted 3D gradient echo with spectral fat saturation were evaluated. MR imaging before USPIO infusion was not performed. The results were correlated with FDG-PET (acquired with dedicated PET camera, visual analysis) and histological findings. The histopathologic axillary staging was negative for nodal malignancy in five patients and positive in the remaining five patients. There was one false positive finding for USPIO-enhanced MR and one false negative finding for FDG-PET. A sensitivity (true positive rate) of 100%, specificity (true negative rate) of 80%, positive predictive value of 80%, and negative predictive value of 100% were achieved for USPIO-enhanced MR and of 80%, 100%, 100%, 80% for FDG-PET, respectively. The most useful sequences in the detection of invaded lymph nodes were in the decreasing order: gadolinium-enhanced T1-weighted 3D gradient echo with fat saturation, T2*-weighted 2D gradient echo, T1-weighted 3D gradient echo and T2-weighted 2D spin echo. In our study, USPIO-enhanced T1 gradient echo after gadolinium injection and fat saturation emerged as a very useful sequence in the staging of lymph nodes. The combination of USPIO-enhanced MR and FDG-PET achieved 100% sensitivity, specificity, PPV and NPV. If these results are confirmed, the combination of USPIO MR with FDG-PET has the potential to identify the patient candidates for axillary dissection versus sentinel node lymphadenectomy.     

Targeted proteins for diagnostic imaging: does chemistry make a difference?

The Oyen et al. study is valuable in that it systematically evaluates several of the factors involved in radiolabeled protein uptake and retention in infectious foci. The role of particular proteins and their receptor specific interactions seems to be inconsequential in agreement with the findings of other. However, the role of the radiolabel was shown to be important and significant differences were delineated from comparisons of the radionuclides and their associated chemistries. The conclusion implicating radionuclide chemistry and associated linkages underscores the need to optimize the attachment and labeling chemical modifications of protein carriers. Evaluation criteria should include serum stability, determination and assessment of the effect of molar substitution ratio, and potential for improving blood clearance without reducing the target-to-non-target ratio. Important areas for future study include characterization of radioactive metabolites and the design and synthesis of new ligands which direct the disposition of metabolites reducing retention in normal organs or accelerating renal excretion. Additionally, intracellular processing of radiolabel, compartmental distribution and strategies for augmenting internalization and retention within the target cell merit detailed exploration. For each radionuclide of interest, 111In, radioiodines, 99mTc and others, improved chemical moieties exist for controlling radiolabel fate. When carrying out mechanistic and evaluative studies, clear-cut conclusions will only be reached when defined and controlled chemistry is used. Having established a "gold standard," simplifications in radiolabeling and other chemical refinements can then be pursued with a quantitative understanding of the trade-offs in targeting agent performance versus other considerations such as cost reduction, simplicity, and convenience.     

Lacrimal gland lesions: Can addition of diffusion-weighted MR imaging improve diagnostic accuracy in characterization?

The aim of the work

To evaluate the diagnostic value of apparent diffusion coefficient (ADC) maps in the characterization of lacrimal gland lesions.

Material and methods

A retrospective study was conducted on 40 patients (26 female and 14 male subjects aged 13–74 years) with lacrimal gland mass. They underwent echo-planar diffusion-weighted magnetic resonance imaging (MRI) of the orbit with a b-factor of 0500 and 1000 s/mm² at 3-Tesla magnetic resonance (MR) unit. ADC maps were reconstructed and the ADC of each mass lesion was calculated. Lesion diagnosis was confirmed by the clinical follow-up or the results of histopathology analysis depending on the specific disease to identify the specificity, sensitivity and accuracy of diffusion-weighted imaging (DWI) in the differentiation between benign and malignant lacrimal lesions.

Results

Forty-two lesions were detected in the examined 40 patients included in this study. Thirty-one were benign and 11 were malignant. The mean ADC value of the malignant lacrimal tumors (0.76 ± 0.14 × 10⁻³ mm²/s) was significantly (P = 0.001) lower than that of the benign lacrimal lesions (1.17 ± 0.22 × 10⁻³ mm²/s). A statistically significant (P = 0.001) difference is identified between the subjects with lacrimal adenitis and those with idiopathic orbital inflammatory syndrome (orbital pseudotumor). Lacrimal lymphoma has the lowest ADCs among a wide range of lacrimal masses. The selection of an ADC value of 0.90 × 10⁻³ mm²/s as a threshold value for differentiating malignant tumors from benign lacrimal lesions has an accuracy of 90%, a sensitivity of 90%, and specificity of 89%.

Conclusion

ADC offers a useful reliable safe non-invasive imaging parameter that can be used for the differentiation of malignant tumors from benign lacrimal lesions with high sensitivity and specificity. The absence of contrast media in DWI reduces the cost of the examination and leads to an increase in the overall accuracy of MRI, hence reducing the number of false positive results and consequently reducing the number of unnecessary biopsies.     

Cardiovascular PET/MR imaging: Quo Vadis?

Journal of Nuclear Cardiology - With the recent advent of PET/MRI scanners, the combination of molecular imaging with a variety of known and novel PET radiotracers, the high spatial resolution of...     

Can integrated 18F-FDG PET/MR replace sentinel lymph node resection in malignant melanoma?

Purpose

To compare the sensitivity and specificity of 18F-fluordesoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT), 18F-FDG PET/magnetic resonance (18F-FDG PET/MR) and 18F-FDG PET/MR including diffusion weighted imaging (DWI) in the detection of sentinel lymph node metastases in patients suffering from malignant melanoma.

Material & Methods

Fifty-two patients with malignant melanoma (female: n =?30, male: n =?22, mean age 50.5?±?16.0 years, mean tumor thickness 2.28?±?1.97 mm) who underwent 18F-FDG PET/CT and subsequent PET/MR & DWI for distant metastasis staging were included in this retrospective study. After hybrid imaging, lymphoscintigraphy including single photon emission computed tomography/CT (SPECT/CT) was performed to identify the sentinel lymph node prior to sentinel lymph node biopsy (SLNB). In a total of 87 sentinel lymph nodes in 64 lymph node basins visible on SPECT/CT, 17 lymph node metastases were detected by histopathology. In separate sessions PET/CT, PET/MR, and PET/MR & DWI were assessed for sentinel lymph node metastases by two independent readers. Discrepant results were resolved in a consensus reading. Sensitivities, specificities, positive predictive values and negative predictive values were calculated with histopathology following SPECT/CT guided SLNB as a reference standard.

Results

Compared with histopathology, lymph nodes were true positive in three cases, true negative in 65 cases, false positive in three cases and false negative in 14 cases in PET/CT. PET/MR was true positive in four cases, true negative in 63 cases, false positive in two cases and false negative in 13 cases. Hence, we observed a sensitivity, specificity, positive predictive value and negative predictive value of 17.7, 95.6, 50.0 and 82.3% for PET/CT and 23.5, 96.9, 66.7 and 82.3% for PET/MR. In DWI, 56 sentinel lymph node basins could be analyzed. Here, the additional analysis of DWI led to two additional false positive findings, while the number of true positive findings could not be increased.

Conclusion

In conclusion, integrated 18F-FDG PET/MR does not reliably differentiate N-positive from N-negative melanoma patients. Additional DWI does not increase the sensitivity of 18F-FDG PET/MR. Hence, sentinel lymph node biopsy cannot be replaced by 18F-FDG-PE/MR or 18F-FDG-PET/CT.