Tunneled hemodialysis catheter insertion: Above, within, or below the right atrium-Where is the tip?

Background: One major challenge when inserting a tunneled, cuffed central venous catheter (CVC) for hemodialysis under fluoroscopy is to accurately place the catheter tip by assessing its position in relation to the cardiac silhouette to approximate the right atrium (RA). Purpose: To investigate whether a weighted mean calculated from published results for two two-dimensional landmark reference distances may be useful in assessing CVC tip positions in relation to the RA. Material and Methods: Central venous catheter tip positions attained under fluoroscopic imaging during insertion using the cardiac silhouette as approximation were retrospectively related to two reference distances (carina to cranial RA border and craniocaudal RA extent), which were used to group catheter tip locations above (1), within (2), or below (3) the RA (henceforth referred to as landmark technique approximation, LTA). The LTA-derived catheter tip locations were validated by correlation with postinterventional computed tomography (CT) datasets acquired shortly after implantation (if available). Results: Based on LTA, 45 catheter tips (10.6%) were above, 179 (42.2%) within, and 200 (47.2%) below the RA. Postinterventional CT (n = 57; 13.4%) visualized 26.3% above, 66.7% within, and 7.0% below the RA. Conclusion: The LTA reference distances appear to lead to a rather low categorization of the CVC tips, or the tips have been placed rather low in the study population. Validation using postinterventional CT indicated an underestimation of the RA in the LTA. Patient characteristics with a higher risk of false estimation through LTA have been defined.

Impact of double reading on NI-RADS diagnostic accuracy in reporting oral squamous cell carcinoma surveillance imaging - a single-center study.

OBJECTIVES: The Neck Imaging Reporting and Data System (NI-RADS) is an increasingly utilized risk stratification tool for imaging surveillance after treatment for head and neck cancer. This study aims to measure the impact of supervision by subspecialized radiologists on diagnostic accuracy of NI-RADS when initial reading is performed by residents. METHODS: 150 CT and MRI datasets were initially read by two trained residents, and then supervised by two subspecialized radiologists. Recurrence rates by NI-RADS category were calculated, and receiver operating characteristic (ROC) curves were plotted. After dichotomization of the NI-RADS system (category 1 vs categories 2 + 3+4 and categories 1 + 2 vs 3 + 4), sensitivity, specificity, positive and negative predictive value were calculated. RESULTS: 26% of the reports were modified by the supervising radiologists. Area under the curve of ROC plots values of the supervision session were higher than those of the initial reading session for both the primary site (0.89 vs 0.86) and the neck (0.94 vs 0.91), but the difference was not statistically significant. For dichotomized NI-RADS category assignments, differences between the initial reading and the supervision session were statistically significant regarding specificity and PPV for the primary site (1 + 2 vs 3 + 4 and 1 vs 2 + 3+4) or even for both sites combined (1 vs 2 + 3+4). CONCLUSION: NI-RADS enables trained resident radiologists to report surveillance imaging in patients with treated oral squamous cell carcinoma with high discriminatory power. Additional supervision by a subspecialized head and neck radiologist particularly improves specificity of radiological reports.

Retrospective Evaluation of NI-RADS for Detecting Postsurgical Recurrence of Oral Squamous Cell Carcinoma on Surveillance CT or MRI.

BACKGROUND. Imaging surveillance is important for the early diagnosis of recurrence after definitive treatment of oral squamous cell carcinoma (OSCC). The Neck Imaging Reporting and Data System (NI-RADS) includes a standardized template for surveillance imaging and categorizes probability of recurrence at the primary site and in the neck (cervical lymph nodes) by assigning categories of 1 (no evidence of recurrence), 2 (low suspicion, subdivided into 2a and 2b for the primary site), 3 (high suspicion), and 4 (definite recurrence). OBJECTIVE. The aim of this study was to determine the rate of locoregional and nodal OSCC recurrence stratified by NI-RADS category among patients undergoing surveillance CT or MRI. METHODS. This retrospective study included 158 patients enrolled in an institutional surveillance program after resection of OSCC with curative intent. A total of 503 contrast-enhanced CT or MRI examinations performed during surveillance were evaluated. Each examination was randomly assigned to one of four radiologists with expertise in head and neck imaging, who provided NI-RADS categories for the primary site and the neck (1006 assigned NI-RADS categories). NI-RADS performance in identifying recurrence was assessed by ROC curve analysis. All four readers evaluated 50 randomly assigned cases to determine interreader agreement by use of the Kendall W statistic. RESULTS. Cancer recurrence was confirmed in 7.6% (38/503) of cases for the primary site and in 6.2% (31/503) for the neck. For the primary site, recurrence rates were 1.0% in NI-RADS category 1, 7.1% in category 2a, 5.6% in category 2b, 66.7% in category 3, and 100.0% in category 4. For the neck, recurrence rates were 0.5% in category 1, 7.0% in category 2, 80.0% in category 3, and 100.0% in category 4. NI-RADS had AUC values of 0.934 for the primary site and 0.959 for the neck. Interreader agreement was 0.67 for the primary site and 0.81 for the neck. CONCLUSION. NI-RADS offers excellent discriminatory power in detection of OSCC recurrence, both for the primary site and the neck. CLINICAL IMPACT. Radiologists and maxillofacial surgeons should implement NI-RADS in surveillance regimens for postoperative OSCC to help detect recurrences in an effective and standardized manner using imaging.

In Vivo Quantification of Water Diffusion, Stiffness, and Tissue Fluidity in Benign Prostatic Hyperplasia and Prostate Cancer.

OBJECTIVES: Water diffusion, tissue stiffness, and viscosity characterize the biophysical behavior of tumors. However, little is known about how these parameters correlate in prostate cancer (PCa). Therefore, we paired tomoelastography of the prostate with diffusion-sensitive magnetic resonance imaging for the quantitative mapping of biophysical parameters in benign prostatic hyperplasia (BPH) and PCa. MATERIALS AND METHODS: Multifrequency magnetic resonance imaging elastography with tomoelastography processing was performed at 60, 70, and 80 Hz using externally placed compressed-air drivers. Shear-wave speed (SWS) and loss angle (φ) were analyzed as surrogate markers of stiffness and viscosity-related fluidity in the normal peripheral zone (PZ), hyperplastic transition zone (TZ), which is consistent with BPH, and PCa lesions. The SWS and φ were correlated with the normalized apparent diffusion coefficient (nADC). RESULTS: Thirty-nine men (median age/range, 67/49-88 years), 25 with BPH and 14 with biopsy-proven PCa, were prospectively enrolled in this institutional review board-approved study. The SWS in PCa (3.1 ± 0.6 m/s) was higher than in TZ (2.8 ± 0.3 m/s, P = 0.004) or tended to be higher than in PZ (2.8 ± 0.4 m/s, P = 0.025). Similarly, φ in PCa (1.1 ± 0.1 rad) was higher than in TZ (0.9 ± 0.2 m/s, P < 0.001) and PZ (0.9 ± 0.1 rad, P < 0.001), whereas nADC in PCa (1.3 ± 0.3) was lower than in TZ (2.2 ± 0.4, P < 0.001) and PZ (3.1 ± 0.7, P < 0.001). Pooled nADC was inversely correlated with φ (R = -0.6, P < 0.001) but not with SWS. TZ and PZ only differed in nADC (P < 0.001) but not in viscoelastic properties. Diagnostic differentiation of PCa from normal prostate tissues, as assessed by area under the curve greater than 0.9, was feasible using nADC and φ but not SWS. CONCLUSIONS: Tomoelastography provides quantitative maps of tissue mechanical parameters of the prostate. Prostate cancer is characterized by stiff tissue properties and reduced water diffusion, whereas, at the same time, tissue fluidity is increased, suggesting greater mechanical friction inside the lesion. This biophysical signature correlates with known histopathological features including increased cell density and fibrous protein accumulation.

DCE-MR imaging of orbital lesions: diagnostic performance of the tumor flow residence time τ calculated by a multi-compartmental pharmacokinetic tumor model based on individual factors.

BACKGROUND: Differentiating benign from malignant orbital lesions by imaging and clinical presentation can be challenging. PURPOSE: To differentiate benign from malignant orbital masses using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) based on tumor flow residence time τ calculated with the aid of a pharmacokinetic tumor model. MATERIAL AND METHODS: Sixty patients with orbital masses were investigated by 3-T MRI including dynamic sequences. The signal intensity-time curve after i.v. contrast medium administration within lesions was approximated by Gd-concentration profiles on the basis of model calculations where the tumor is embedded in a whole-body kinetic model. One output of the model was tumor flow residence time τ, defined as the ratio of the tumor volume and the tumor blood flow rate. Receiver operating characteristic (ROC) curves were used to analyze the diagnostic performance of τ. The results were compared with those of Ktrans, kep, ve, iAUC, and ADC. RESULTS: Thirty-one benign and 29 malignant orbital masses were identified (reference standard: histopathology, clinical characteristics). Mean τ was significantly longer for benign masses (94 ± 48 s) than for malignant masses (21 ± 19 s, P < 0.001). ROC analysis revealed the highest area under the curve (AUC = 0.94) for τ in orbital masses compared to standard methods. CONCLUSION: Tumor flow residence times τ of benign and malignant orbital masses are valuable in the diagnostic work-up of orbital tumors. Measures of diagnostic accuracy were superior for τ compared to ADC, Ktrans, ve, and iAUC.

Characterization of orbital masses by multiparametric MRI.

OBJECTIVES: DWI and dynamic contrast enhanced (DCE) MR imaging are techniques that allow insight to tumor vascularity and cellularity. We evaluated the diagnostic performance of multiparametric MRI (mp-MRI) in distinguishing benign from malignant orbital masses using standard anatomic imaging (sAI), DWI and DCE. MATERIALS AND METHODS: This prospective IRB approved study with written informed consent included 65 patients. mp-MRI at 3 Tesla including DWI and DCE was performed in all patients. Parametric maps were generated for obtaining the perfusion parameters including K(trans), kep, ve and iAUC and time-signal intensity curves were recorded to determine the curve pattern. Two radiologists rated the likelihood of malignancy on a five-point scale in three separate, randomized reading sessions (initially only sAI, afterwards sAI+either DWI or DCE and finally sAI+DWI+DCE). Data was statistically analyzed. RESULTS: 33 Patients had malignant orbital masses and 32 patients had benign orbital masses (reference standard histopathology in 35 cases and clinical follow-up in 30 patients). The mean ADC of malignant masses differed significantly from the mean (SD) ADC of benign masses (0.825 [0.437]×10(-3)mm(2)/s and 1.257 [0.576]×10(-3)mm(2)/s, respectively) (p=0.001). K(trans), kep and iAUC were significantly higher in malignant masses (p<0.01). The reading of sAI only resulted in a moderate specificity but poor sensitivity in differentiating benign from malignant lesions. Adding DWI and DCE images improved specificity and sensitivity considerably, being the highest for the combined reading of all sequences. CONCLUSION: mp-MRI is a helpful tool in differentiating malignant orbital lesions from benign masses and should therefore be included in the routine diagnostic protocol for orbital imaging.