The influence of I-131 therapy on FDG uptake in differentiated thyroid cancer

OBJECTIVE: 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) [or PET/computed tomography (CT)] is more likely to show false-negative results when it is performed shortly after chemotherapy and/or radiotherapy because of "metabolic stunning". The present study aimed to evaluate the influence of I-131 therapy on FDG uptake and the detection of recurrence or metastasis of differentiated thyroid cancer (DTC). METHODS: We retrospectively enrolled 16 consecutive FDG-PET/CT studies which had been performed in patients with DTC with elevated thyroglobulin (TG) but negative I-131 whole-body scan. All studies were performed under L: -thyroxine suppression. The patients were divided into groups A and B for PET/CT performed within 4 months of I-131 therapy or no such therapy, respectively. Each lesion identified on PET/CT was characterized using a 5-point scale by visual analysis: 0 = definitely benign, 1 = probably benign, 2 = equivocal, 3 = probably malignant, and 4 = definitely malignant. The maximum standardized uptake value (SUV max) in each lesion was also measured for semiquantitative analysis. We compared the visual grading and SUV max of the lesion of highest FDG uptake between groups A and B. RESULTS: For visual analysis, group B had significantly more patients with an uptake score of 3 or 4 than group A (80% vs. 17%, P = 0.01). In addition, there were significantly more equivocal results from group A than from group B (67% vs. 10%, P = 0.02). If the patients with the highest uptake scores of 2, 3, and 4 were considered to be positive for local recurrence or metastasis, there would be no significant difference between the positive rates of groups A and B (83% vs. 90%, P = 0.7). However, the mean SUV max of positive results was significantly lower for group A than for group B (3.1 +/- 0.9 and 6.6 +/- 3.5, respectively, P = 0.02). CONCLUSIONS: The preliminary results suggested that FDG uptake in DTC may be negatively influenced by I-131 therapy within 4 months, resulting in lower FDG uptake and more equivocal results. Further studies are necessary to determine whether it is secondary to "metabolic stunning" caused by I-131 therapy.     

Three-dimensional SPECT reconstruction with transmission-dependent scatter correction

OBJECTIVE: The quality of single-photon emission computed tomography (SPECT) imaging is hampered by attenuation, collimator blurring, and scatter. Correction for all of these three factors is required for accurate reconstruction, but unfortunately, reconstruction-based compensation often leads to clinically unacceptable long reconstruction times. Especially, efficient scatter correction has proved to be difficult to achieve. The objective of this article was to extend the well-known transmission-dependent convolution subtraction (TDCS) scatter-correction approach into a rapid reconstruction-based scatter-compensation method and to include it into a fast 3D reconstruction algorithm with attenuation and collimator-blurring corrections. METHODS: Ordered subsets expectation maximization algorithm with attenuation, collimator blurring, and accelerated transmission-dependent scatter compensation were implemented. The new reconstruction method was compared with TDCS-based scatter correction and with one other transmission-dependent scatter-correction method using Monte Carlo simulated projection data of (99m)Tc-ECD and (123)I-FP-CIT brain studies. RESULTS: The new reconstruction-based scatter compensation outperformed the other two scatter-correction methods in terms of quantitative accuracy and contrast measured with normalized mean-squared error, gray-to-white matter and striatum-to-background ratios, and also in visual quality. Highest accuracy was achieved when all the corrections (i.e., attenuation, collimator blurring, and scatter) were applied. CONCLUSIONS: The developed 3D reconstruction algorithm with transmission-dependent scatter compensation is a promising alternative to accurate and efficient SPECT reconstruction.     

Estimating the age of immature <Emphasis Type="Italic">Chrysomya albiceps</Emphasis> (Diptera: Calliphoridae), correcting for temperature and geographical latitude

Developmental curves for Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) were established at 13 different constant temperatures using developmental landmarks and length as measures of age. The thermal summation constants (K) and developmental zeros (D (0)) were calculated for five developmental landmarks using the method described by Ikemoto and Takai (Environ Entomol 29:671-682, 2000). Comparison with the K and D (0) values of our findings to those of three previously published studies of C. albiceps suggests that K is directly proportional to geographic latitude, and D (0) is inversely proportional to both K and geographic latitude. Body size and developmental landmarks have a complex relationship because of trade-offs between mortality risk and female fecundity (as measured by body size) at non-optimal temperatures. This relationship can be summarized using superimposed isomorphen and isomegalen diagrams, which can then be used to make forensic estimates of postmortem intervals from larval body lengths. Finally, we recommend that future studies providing data for precise forensic estimates of postmortem intervals should use a relative temporal precision of about 10% of the total duration being measured. For many blowflies, this translates into a sampling interval of approximately every 2 h before hatching, 3 h before first ecdysis and 6 h before second ecdysis.     

Distal Embolic Protection for Renal Arterial Interventions

Distal or embolic protection has intuitive appeal for its potential to prevent embolization of materials generated during interventional procedures. Distal protection devices (DPDs) have been most widely used in the coronary and carotid vascular beds, where they have demonstrated the ability to trap embolic materials and, in some cases, to reduce complications. Given the frequency of chronic kidney disease in patients with renal artery stenosis undergoing stent placement, it is reasonable to propose that these devices may play an important role in limiting distal embolization in the renal vasculature. Careful review of the literature reveals that atheroembolization does occur during renal arterial interventions, although it often goes undetected. Early experience with DPDs in the renal arteries in patients with suitable anatomy suggests retrieval of embolic materials in approximately 71% of cases and renal functional improvement/stabilization in 98% of cases. The combination of platelet inhibition and a DPD may provide even greater benefit. Given the critical importance of renal functional preservation, it follows that everything that can be done to prevent atheroembolism should be undertaken including the use of DPDs when anatomically feasible. The data available at this time support a beneficial role for these devices. Dr. Murphy has support as follows: supported by grants HL071556-01 and HL077221 from the National Heart, Lung, & Blood Institute, and also received research grants from Boston Scientific, Guidant, Cordis, and Otsuka Pharmaceuticals.     

Computer-assisted total knee arthroplasty versus the conventional technique: how precise is navigation in clinical routine?

Restoration of the mechanical leg axis and component positioning are crucial factors affecting long-term results in total knee arthroplasty (TKA). In a prospective study, 1,000 patients were operated on either using a CT-free navigation system or the conventional jig-based technique. Leg alignment and component orientation were determined on postoperative X-rays. The mechanical leg axis was significantly better in the computer-assisted group (95%, within ±3° varus/valgus) compared to the conventional group (74%, within ±3° varus/valgus) (P < 0.001). On average, the operating time was increased by 8 min in the computer-assisted group. No significant differences were seen between senior and younger surgeons regarding postoperative leg alignment and operating time. Computer-assisted TKA leads to a more accurate restoration of leg alignment and component orientation compared to the conventional jig-based technique. Potential benefits in long-term outcome and functional improvement require further investigation.     

An automated procedure for the assessment of white matter hyperintensities by multispectral (T1, T2, PD) MRI and an evaluation of its between-centre reproducibility based on two large community databases

Introduction An automated procedure for the detection, quantification, localization and statistical mapping of white matter hyperintensities (WMH) on T2-weighted magnetic resonance (MR) images is presented and validated based on the results of a between-centre reproducibility study. Methods The first step is the identification of white matter (WM) tissue using a multispectral (T1, T2, PD) segmentation. In a second step, WMH are identified within the WM tissue by segmenting T2 images, isolating two different classes of WMH voxels – low- and high-contrast WMH voxels, respectively. The reliability of the whole procedure was assessed by applying it to the analysis of two large MR imaging databases (n = 650 and n= 710, respectively) of healthy elderly subjects matched for demographic characteristics. Results Average overall WMH load and spatial distribution were found to be similar in the two samples, (1.81 and 1.79% of the WM volume, respectively). White matter hyperintensity load was found to be significantly associated with both age and high blood pressure, with similar effects in both samples. With specific reference to the 650 subject cohort, we also found that WMH load provided by this automated procedure was significantly associated with visual grading of the severity of WMH, as assessed by a trained neurologist. Conclusion The results show that this method is sensitive, well correlated with semi-quantitative visual rating and highly reproducible.     

Skull base: pseudolesion or true lesion?

The skull base is a complex anatomical structure. Therefore, radiologists often use “side-to-side” comparison for detection of abnormalities. This approach is compromised by the high frequency of anatomical variations involving the skull base and the common presence of flow-related artifacts within vessels at the skull base that might mimic true lesions. The spectrum of “pseudolesions” ranging from different anatomical variations, such as unusual arachnoid granulations, asymmetric pneumatization and/or appearance of neurovascular foramina, to flow-related artifacts will be discussed in this review article, and tips for their distinction from a true lesion in a similar location will be given.     

Sequential tibial and peroneal intraneural ganglia arising from the superior tibiofibular joint

We present a patient who developed a peroneal intraneural ganglion and an adventitial cyst following the incomplete treatment of a tibial intraneural ganglion. These separate cysts all originated from the superior tibiofibular joint and dissected along their respective articular branches. A logical mechanistic explanation for these coexisting cysts is provided, which highlights the shared pathogenesis—its joint-related nature—rather than a multifocal de novo process. These observations would not only be consistent with, but would extend previous evidence in support of, the unifying articular (synovial) theory.     

Magnetic resonance imaging of surgically confirmed anterior cruciate ligament graft disruption

Objective To evaluate previously described primary and secondary MRI signs of disruption to anterior cruciate ligament (ACL) grafts in surgically proven cases. Materials and methods We retrospectively analyzed MR images of 48 patients (mean age 29 years) with clinically suspected ACL graft disruption. All patients had surgical confirmation of the MRI findings. The reviewers analyzed the cases blinded to the surgical results and assessed each of the primary and secondary MRI signs of graft disruption individually. Subsequently, a final impression of the graft integrity based on a comprehensive assessment of all of the primary and secondary findings was made. Results Utilizing a comprehensive assessment of previously described primary and secondary MR findings of ACL graft disruption, the blinded reviewers were able to identify correctly full-thickness graft tears with test accuracy of 85%, sensitivity of 72%, and specificity of 100%. Individual assessment of the primary finding of graft fiber discontinuity had sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 72%, 100%, 100%, 77% and 85%, respectively, for full-thickness tears. Other individual primary and secondary findings were less reliable; however, the primary findings of marked segmental thinning of the graft and markedly abnormal graft orientation, and the secondary findings of bone contusions in the lateral compartment and large joint effusion, had high specificity and positive predictive value. Of the four missed cases, two had associated arthrofibrosis. Conclusion The comprehensive assessment of previously described primary and secondary MRI findings of ACL graft disruption has high test specificity and moderately high test accuracy. The presence of graft fiber discontinuity is the most reliable primary or secondary finding when assessed individually. Marked segmental thinning of the graft and abnormal fiber orientation, and the presence of bone contusions in the lateral compartment and large joint effusion, are less reliable overall but are highly suggestive of full-thickness graft tear when present.     

Percutaneous Cryoablation and Vertebroplasty: A Case Report

A 70-year-old man with a painful vertebral metastasis was treated with combined percutaneous cryoablation and vertebroplasty therapy (CVT) in one session. The patient was suffering from diffuse visceral metastasized cholangiocarcinoma. After several weeks of back pain, magnetic resonance imaging documented a single L2 bone metastasis. In consultation with the oncologists, palliative combined CVT was administered with the aim of obtaining pain relief and bone stabilization. In our experience this combined treatment is safe and effective for immediate pain relief in painful bone metastases when other standard palliative treatments have failed.