Safety and feasibility of percutaneous vertebroplasty with radioactive (153)Sm PMMA in an animal model

Purpose

We investigated the safety and feasibility of the combination of samarium-153-ethylenediamine tetramethylene phosphonate (¹⁵³Sm-EDTMP)-incorporated bone cement (BC) with percutaneous vertebroplasty (PVP) in dogs.

Methods and materials

¹⁵³Sm-EDTMP-incorporated BC was prepared by combining solid ¹⁵³Sm-EDTMP and polymethylmethacrylate (PMMA) immediately before PVP. It was then injected into the vertebrae of four healthy mongrel dogs (two males and two females) by PVP under CT guidance. Each dog was subjected to five PVP sessions at a ¹⁵³Sm-EDTMP dose of 30-70 mCi. The suppressive effect of local injection of ¹⁵³Sm-EDTMP on the hematopoietic system was evaluated through counting of peripheral blood cells. Distribution of ¹⁵³Sm-EDTMP-incorporated BC and the status of tissues adjacent to injected vertebrae were evaluated with SPECT, CT and MRI. Histopathology was carried out to assess the influence of PVP on the vertebra and adjacent tissues at the microscopic level.

Results

PVP was done successfully, and all dogs exhibited normal behavior and stable physical signs after procedures. ¹⁵³Sm-EDTMP-incorporated BC was concentrated mainly in target vertebrae, and the peripheral blood cells remained within normal range. The spinal cord and tissues around BC did not exhibit signs of injury even when the dosage of ¹⁵³Sm-EDTMP increased from 30 mCi to 70 mCi.

Conclusion

A dose lower than 70 mCi of ¹⁵³Sm is safe when it was injected into vertebrae. ¹⁵³Sm-EDTMP-incorporated BC did not influence the effect of PVP. This means might strengthen anti-tumor activity locally for vertebra with osseous metastasis without damaging adjacent tissues.     

Systematic review on physician's knowledge about radiation doses and radiation risks of computed tomography

Background

The frequent use of computed tomography is a major cause of the increasing medical radiation exposure of the general population. Consequently, dose reduction and radiation protection is a topic of scientific and public concern.

Aim

We evaluated the available literature on physicians’ knowledge regarding radiation dosages and risks due to computed tomography.

Methods

A systematic review in accordance with the Cochrane and PRISMA statements was performed using eight databases. 3091 references were found. Only primary studies assessing physicians’ knowledge about computed tomography were included.

Results

14 relevant articles were identified, all focussing on dose estimations for CT. Overall, the surveys showed moderate to low knowledge among physicians concerning radiation doses and the involved health risks. However, the surveys varied considerably in conduct and quality. For some countries, more than one survey was available. There was no general trend in knowledge in any country except a slight improvement of knowledge on health risks and radiation doses in two consecutive local German surveys.

Conclusions

Knowledge gaps concerning radiation doses and associated health risks among physicians are evident from published research. However, knowledge on radiation doses cannot be interpreted as reliable indicator for good medical practice.     

Evaluation of gross tumor size using CT, 18F-FDG PET, integrated 18F-FDG PET/CT and pathological analysis in non-small cell lung cancer

Purpose

The correlation of gross tumor sizes between combined ¹⁸F-FDG PET/CT images and macroscopic surgical samples has not yet been studied in detail. In the present study, we compared CT, ¹⁸F-FDG PET and combined ¹⁸F-FDG PET/CT for the delineation of gross tumor volume (GTV) and validated the results through examination of the macroscopic surgical specimen.

Methods

Fifty-two operable non-small cell lung cancer (NSCLC) patients had integrated ¹⁸F-FDG PET/CT scans preoperatively and pathological examination post-operation. Four separate maximal tumor sizes at X (lateral direction), Y (ventro-dorsal direction) and Z (cranio-caudal direction) axis were measured on ¹⁸F-FDG PET, CT, combined ¹⁸F-FDG PET/CT and surgical specimen, respectively. Linear regression was calculated for each of the three imaging measurements versus pathological measurement.

Results

No significant differences were observed among the tumor sizes measured by three images and pathological method. Compared with pathological measurement, CT size at X, Y, Z axis was larger, whereas combined ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET size were smaller. Combined ¹⁸F-FDG PET/CT size was more similar to the pathological size than that of ¹⁸F-FDG PET or CT. Results of linear regressions showed that integrated ¹⁸F-FDG PET/CT was the most accurate modality in measuring the size of cancer.

Conclusions

¹⁸F-FDG PET/CT correlates more faithfully with pathological findings than ¹⁸F-FDG PET or CT. Integrated ¹⁸F-FDG PET/CT is an effective tool to define the target of GTV in radiotherapy.     

Diagnostic accuracy and tolerability of contrast enhanced CT colonoscopy in symptomatic patients with increased risk for colorectal cancer

Objective

We compared the accuracy and tolerability of intravenous contrast enhanced spiral computed tomography colonography (CTC) and optical colonoscopy (OC) for the detection of colorectal neoplasia in symptomatic patients for colorectal neoplasia.

Methods

A prospective study was performed in 48 patients with symptomatic patients with increased risk for colorectal cancer. Spiral CTC was performed in supine and prone positions after colonic cleansing. The axial, 2D MPR and virtual endoluminal views were analyzed. Results of spiral CTC were compared with OC which was done within 15 days. The psychometric tolerance test was asked to be performed for both CTC and colonoscopy after the procedure.

Results

Ten lesions in 9 of 48 patients were found in CTC and confirmed with OC. Two masses and eight polyps, consisted of 1 tubulovillous, 1 tubular, 2 villous adenoma, 4 adenomatous polyp, 4 adenocarcinoma, were identified. Lesion prevalence was 21%. Sensitivity, specificity, accuracy, positive and negative predictive values were found 100%, 87%, 89%, 67% and 100%, respectively. Psychometric tolerance test showed that CTC significantly more comfortable comparing with OC (p = 0.00). CTC was the preferred method in 37% while OC was preferred in 6% of patients. In both techniques, the most unpleasant part was bowel cleansing.

Conclusion

Contrast enhanced CTC is a highly accurate method in detecting colorectal lesions. Since the technique was found to be more comfortable and less time consuming compare to OE, it may be preferable in management of symptomatic patients with increased risk for colorectal cancer.     

Comparison of high-dose rate prostate brachytherapy dose distributions with iridium-192, ytterbium-169, and thulium-170 sources

Purpose

Recent studies have identified that among different available radionuclides, the dose characteristics and shielding properties of ytterbium-169 (¹⁶⁹Yb) and thulium-170 (¹⁷⁰Tm) may suit high-dose rate (HDR) brachytherapy needs. The purpose of this work was to compare clinically optimized dose distributions using proposed ¹⁶⁹Yb and ¹⁷⁰Tm HDR sources with the clinical dose distribution from a standard microSelectron V2 HDR iridium-192 (¹⁹²Ir) brachytherapy source (Nucletron B.V., Veenendaal, The Netherlands).

Methods and materials

CT-based treatment plans of 10 patients having prostate volumes ranging from 17 to 92 cm³ were studied retrospectively. Clinical treatment of these patients involved 16 catheters and a microSelectron V2 HDR ¹⁹²Ir source. All dose plans were generated with inverse planning simulated annealing optimization algorithm. Dose objectives used for the ¹⁹²Ir radionuclide source were used for the other two radionuclides. The dose objective parameters were adjusted to obtain the same clinical target (prostate) volume coverage as the original ¹⁹²Ir radionuclide plan. A complete set of dosimetric indices was used to compare the plans from different radionuclides. A pairwise statistical analysis was also performed.

Results and conclusions

All the dose distributions optimized with specific ¹⁹²Ir, ¹⁶⁹Yb, and ¹⁷⁰Tm sources satisfied the standard clinical criteria for HDR prostate implants, such as those for the Radiation Therapy Oncology Group clinical trial 0321, for combined HDR and external beam treatment for prostate adenocarcinoma. For equivalent clinical target volume dose coverage, the specific ¹⁶⁹Yb and ¹⁷⁰Tm sources resulted in a statistically significant dose reduction to organs at risk compared with microSelectron V2 HDR ¹⁹²Ir source. This study indicates that a ¹⁷⁰Tm or ¹⁶⁹Yb radionuclide source may be an alternative to the ¹⁹²Ir radionuclide sources in HDR brachytherapy.     

Present and future of PET and PET/CT in gynaecologic malignancies

Objectives

To review the published data in literature on patients affected by gynaecological malignancies to establish the role of ¹⁸F-FDG positron emission tomography (PET) and PET/CT in comparison to conventional imaging (CI).

Materials and methods

All papers specifically addressed to the role of ¹⁸F-FDG PET and PET/CT in gynaecological malignancies published on PubMed/Medline, in abstracts from the principal international congresses, in the guidelines from national Societies that had appeared in literature until November 2009 were considered for the purpose of the present study.

Results and conclusions

The use of ¹⁸F-FDG PET, and even more of ¹⁸F-FDG PET/CT, is increasing in the follow up of patients with gynaecologic malignancies and suspected recurrent disease: there is evidence in the literature that ¹⁸F-FDG PET/CT has a higher sensitivity than CI in depicting occult metastatic spread. An interesting issue is represented by patients with ovarian cancer with an increase of the specific biomarker, CA-125, and negative/inconclusive findings at CI. The use of ¹⁸F-FDG PET in differential diagnosis and staging is more controversial, but there is some evidence that a baseline PET examination performed before commencing therapy, for staging purpose, is also useful to evaluate the response to chemoradiation treatment. In several papers it has been suggested a relevant role of ¹⁸F-FDG PET/CT in evaluating the entity of response to treatment and therefore to plan the subsequent therapeutic strategy.     

P magnetic resonance spectroscopy to measure in vivo cardiac energetics in normal myocardium and hypertrophic cardiomyopathy: Experiences at 3 T

Background

³¹P magnetic resonance spectroscopy (MRS) allows measurement of in vivo high-energy phosphate kinetics in the myocardium. While traditionally ³¹P cardiac spectroscopy is performed at 1.5 T, cardiac MRS at higher field strength can theoretically increase signal to noise ratio (SNR) and spectral resolution therefore improving sensitivity and specificity of the cardiac spectra. The reproducibility and feasibility of performing cardiac spectroscopy at 3 T is presented here in this study in healthy volunteers and patients with hypertrophic cardiomyopathy.

Methods

Cardiac spectroscopy was performed using a Phillips 3T Achieva scanner in 37 healthy volunteers and 26 patients with hypertrophic cardiomyopathy (HCM) to test the feasibility of the protocol. To test the reproducibility a single volunteer was scanned eight times on separate occasions. A single voxel ³¹P MRS was performed using Image Selected In vivo Spectroscopy (ISIS) volume localization.

Results

The mean phosphocreatine/adenosine triphosphate (PCr/ATP) ratio of the eight measurements performed on one individual was 2.11 ± 0.25. Bland Altman plots showed a variance of 12% in the measurement of PCr/ATP ratios. The PCr/ATP ratio was significantly reduced in HCM patients compared to controls, 1.42 ± 0.51 and 2.11 ± 0.57, respectively, P < 0.0001. (All results are expressed as mean ± standard deviation).

Conclusions

Here we demonstrate that cardiac ³¹P MRS at 3 T is a reliable method of measuring in vivo high-energy phosphate kinetics in the myocardium for clinical studies and diagnostics. Based on our data an impairment of cardiac energetic state in patients with hypertrophic cardiomyopathy is indisputable.     

Validity of apparent diffusion coefficient hyperpolarized 3He-MRI using MSCT and pulmonary function tests as references

Purpose

To compare apparent diffusion coefficient (ADC) measurements from hyperpolarized (HP) helium (³He)-magnetic resonance imaging (MRI) with quantitative data from multislice Computed Tomography (CT) (MSCT) of the whole lungs and pulmonary function tests (PFT).

Materials and methods

Twenty-seven subjects, 22 with established emphysema and 5 with preclinical emphysema defined by PFT criteria, were examined with HP ³He-MRI and MSCT. Mean age was 55 (±12) years, 18 female and 9 male. Mean ADC from ³He-MRI was compared with emphysema index (EI), 15th percentile and mean lung density (MLD) values from MSCT. Both mean ADC and MSCT data were compared to PFT, especially percent of predicted diffusing capacity of carbon monoxide (%predicted DLCO), using Pearson's correlation test.

Results

Mean ADC and standard deviation values were 0.392 ± 0.119 cm²/s for the established emphysema group and 0.216 ± 0.046 for the pre-clinical emphysema group. MSCT values for the established emphysema group and pre-clinical emphysema group were: EI (%) 11 ± 12 and 0.4 ± 0.6, respectively; 15th percentile (Hounsfield Units (HU)), −956 ± 25 and −933 ± 13, respectively and MLD (HU) −877 ± 20 and −863 ± 15, respectively. Correlations between mean ADC and EI and 15th percentile were both r = 0.90 and for MLD r = 0.59. There was higher correlation between mean ADC and %predicted DLCO (r = 0.90) than between EI and %predicted DLCO (r = 0.76).

Conclusion

HP ³He-MRI correlates well with density measurements from MSCT and agrees better than MSCT with %predicted DLCO which is the PFT most related to emphysema.     

The potential clinical value of FDG-PET for recurrent renal cell carcinoma

Purpose

The clinical value of positron emission tomography (PET) using ¹⁸F-fluorodeoxyglucose (FDG) for follow-up or suspected recurrence of renal cell carcinoma (RCC) has not been fully evaluated. The purpose of this study was to assess the diagnostic performance of FDG-PET for postoperative assessment in patients with RCC.

Methods

We reviewed 28 scans in 23 patients who had undergone FDG-PET scans after surgery for RCC. Diagnostic accuracy of visually interpreted PET was evaluated based on final diagnoses obtained histologically or by clinical follow-up at least 6 months. Also, additional information over CT, influence on treatment decisions, and the accuracy of FDG uptake as a predictor of survival were assessed.

Results

Recurrence of renal carcinoma was histologically (n = 15) or clinically (n = 6) confirmed in 21 of 28 cases. Overall, the sensitivity, specificity, and diagnostic accuracy using FDG-PET were 81%, 71%, and 79%, respectively. In papillary RCC, the sensitivity was 100%; however, that was 75% in clear cell RCC in patient-basis. PET correctly detected local recurrence and metastases in all cases in the peritoneum, bone, muscle and adrenal gland. Additional information was obtained from scans in 6 cases (21%), which influenced therapeutic management in 3 cases (11%). Cumulative survival rates over 5 years in the PET-positive vs. the PET-negative group were 46% vs. 83%, respectively (p = 0.17).

Conclusions

FDG-PET would be useful for postoperative surveillance in patients with RCC, although its impact on treatment decisions may be limited. Further investigations are necessary to conclude whether PET has a prognostic value.     

Bioevaluation study of P-CP-PLLA particle brachytherapy in a rabbit VX2 lung tumor model

Objective

The purpose of this study was to investigate the therapy effects of intratumoral administration of ³²P-CP-PLLA particles in a rabbit VX2 lung tumor model.

Methods

16 rabbits with tumors were randomly divided into 4 groups. 4 rabbits served as untreated controls, and others received intratumoral administration of ³²P-CP-PLLA particles with CT guidance. The total radioactivities in treated groups were as follows: a low activity was 93 MBq (n=4) (group 1), a medium activity was 185 MBq (n=4) (group 2) and a high activity was 370 MBq (n=4) (group 3). Brachytherapy treated VX2 tumors underwent ¹⁸F-FDG PET/CT at 0 day, 3 day, 7 day and 14 day postinjection. In control group, ¹⁸F-FDG PET/CT images were acquired at the same time points but without any treatment. Bremsstrahlung SPECT images were performed at 14 days after intratumoral brachytherapy in treated groups. After Bremsstrahlung SPECT and last ¹⁸F-FDG PET/CT imagings, the rabbits were euthanized and the tumors were removed for histological examination.

Results

Bremsstrahlung SPECT images study indicated that there was no leakage of ³²P out of the injection site at 14 days after treatment. Compared with the control, the tumor volumes in treated groups significantly decreased, and ³²P-CP-PLLA particle produced a reduction in maximum or mean SUV of VX2 tumor (p<0.05). The percentage changes in maximum and mean SUV gradually decreased in group 1 and group 2 from day 3 to day 14 (p<0.05). A transient increase in ¹⁸F-FDG accumulation at group 3 occurred due to the inflammatory reaction elements. Activity dependence was seen in HE and PCNA staining after 14 days treatment among three treated groups (p<0.05).

Conclusions

Our data suggested that ³²P-CP-PLLA particle localized on the injecting sites. This novel brachytherapy device efficiently suppressed the growth of the VX2 tumors implanted in the rabbit.     

Diagnostic Performance of 68Ga-DOTATATE PET/CT, 18F-FDG PET/CT and 131I-MIBG Scintigraphy in Mapping Metastatic Pheochromocytoma and Paraganglioma

Purpose

To evaluate the diagnostic performance of ⁶⁸Ga-DOTATATE ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT), ¹⁸F-FDG PET/CT and ¹³¹I-MIBG scintigraphy in the mapping of metastatic pheochromocytoma and paraganglioma.

Materials and Methods

Seventeen patients (male = 8, female = 9; age range, 13–68 years) with clinically proven or suspicious metastatic pheochromocytoma or paraganglioma were included in this prospective study. Twelve patients underwent all three modalities, whereas five patients underwent ⁶⁸Ga-DOTATATE and ¹³¹I-MIBG without ¹⁸F-FDG. A composite reference standard derived from anatomical and functional imaging findings, along with histopathological information, was used to validate the findings. Results were analysed on a per-patient and on per-lesion basis. Sensitivity and accuracy were assessed using McNemar’s test.

Results

On a per-patient basis, 14/17 patients were detected in ⁶⁸Ga-DOTATATE, 7/17 patients in ¹³¹I-MIBG, and 10/12 patients in ¹⁸F-FDG. The sensitivity and accuracy of ⁶⁸Ga-DOTATATE, ¹³¹I-MIBG and ¹⁸F-FDG were (93.3 %, 94.1 %), (46.7 %, 52.9 %) and (90.9 %, 91.7 %) respectively. On a per-lesion basis, an overall of 472 positive lesions were detected; of which 432/472 were identified by ⁶⁸Ga-DOTATATE, 74/472 by ¹³¹I-MIBG, and 154/300 (patient, n = 12) by ¹⁸F-FDG. The sensitivity and accuracy of ⁶⁸Ga-DOTATATE, ¹³¹I-MIBG and ¹⁸F-FDG were (91.5 %, 92.6 % p < 0.0001), (15.7 %, 26.0 % p < 0.0001) and (51.3 %, 57.8 % p < 0.0001) respectively. Discordant lesions were demonstrated on ⁶⁸Ga-DOTATATE, ¹³¹I-MIBG and ¹⁸F-FDG.

Conclusions

Ga-DOTATATE PET/CT shows high diagnostic accuracy than ¹³¹I-MIBG scintigraphy and ¹⁸F-FDG PET/ CT in mapping metastatic pheochromocytoma and paraganglioma.     

MRI findings in renal transplant recipients with hip and knee pain

Purpose

To evaluate and demonstrate the MRI findings of renal transplant recipients with hip and knee pain and to investigate the most common etiology of pain.

Materials and methods

69 hip MRIs of 57 patients with hip pain and 30 knee MRIs of 24 patients with knee pain with no history of trauma were retrospectively evaluated by two radiologists.

Results

In the evaluation of hip MRIs, 24 patients had avascular necrosis and effusion, 2 patients had bone marrow edema consistent with early stage of avascular necrosis. 18 patients had only intraarticular effusion, 6 patients had tendinitis, 6 patients had bursitis and 1 patient had soft tissue abscess. Five patients had muscle edema and five patients had muscle atrophy as additional findings to the primary pathologies. Among patients with knee pain, nine patients had degenerative joint disease. Seven patients had chondromalacia, five had bone marrow edema, six had meniscal tear, six had ligament rupture and two had bone infarct. Three of the patients had muscle edema accompanying to other pathologies.

Conclusion

The most common etiology of hip pain in renal transplant recipients is avascular necrosis as expected, intraarticular effusion is found to be the second reason for pain. However, knee pain is explained by ligament pathology, meniscal tear, chondromalacia or degenerative joint disease rather than osteonecrosis.     

Clinical values for abnormal F-FDG uptake in the head and neck region of patients with head and neck squamous cell carcinoma

Purpose

Fluorine 18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) is used to identify index or second primary cancer (SP) of the head and neck (HN) through changes in ¹⁸F-FDG uptake. However, both physiologic and abnormal lesions increase ¹⁸F-FDG uptake. Therefore, we evaluated ¹⁸F-FDG uptake in the HN region to determine clinical values of abnormal tracer uptake.

Methods

A prospective study approved by the institutional review board was conducted in 314 patients with newly diagnosed HN squamous cell carcinoma (HNSCC) and informed consent was obtained from all enrolled patients. The patients received initial staging workups including ¹⁸F-FDG PET/CT and biopsies. All lesions with abnormal HN ¹⁸F-FDG uptake were recorded and most of those were confirmed by biopsies. Diagnostic values for abnormal ¹⁸F-FDG uptake were calculated.

Results

Abnormal ¹⁸F-FDG uptake was identified in primary tumors from 285 (91.9%) patients. False-negative results were obtained for 22.3% (23/103) T1 tumors and 2.2% (2/93) T2 tumors (P < 0.001). Thirty-eight regions of abnormal ¹⁸F-FDG uptake were identified in 36 (11.5%) patients: the thyroid (n = 13), maxillary sinus (n = 7), palatine tonsil (n = 6), nasopharynx (n = 5), parotid gland (n = 2) and others (n = 5). Synchronous SP of the HN was identified in eight (2.5%) patients: the thyroid (n = 5), palatine tonsil (n = 2), and epiglottis (n = 1). The sensitivity and specificity of ¹⁸F-FDG PET/CT for identification of SPs were 75.0% and 98.7%, respectively.

Conclusions

¹⁸F-FDG PET/CT is a reliable method for tumor staging and identify SP in HN region, promoting appropriate therapeutic planning. Additional examinations may be required to identify superficial or small-volume tumors.     

MRI assessment of changes in liver iron deposition post-venesection

Objective

The aim of this study was to determine if changes in hepatic iron content in patients with hemochromatosis pre- and post-venesection could be detected by changes in liver signal intensity with MRI.

Materials and methods

The study was performed with institutional ethics approval and with informed consent. Gradient echo images were performed on 20 patients with hemochromatosis pre- and post-venesection and 10 control subjects: gradient echo T1-weighted in- and out-phases (4.54 (in)/2.27 (out), 167 [TE/TR], Flip 70°) and gradient echo T2* (5/18 [TE/TR], Flip 10°). The liver to muscle signal ratio was compared pre- and post-venesection.

Results

All MRI sequences showed significant correlation between the liver to muscle signal intensity ratio and the serum ferritin pre-venesection [r = −0.70, −0.65, −0.74, −0.72, in/out/T2*r/T2*, respectively]. There was a significant increase on all sequences in the liver to muscle signal intensity ratio post-venesection (p < 0.001). The control group and patients post-venesection had almost identical liver to muscle signal intensity ratios.

Conclusion

The reduction in liver signal intensity caused by iron excess in hemochromatosis returns to normal post-venesection. Measurement of liver to muscle signal intensity ratios may be a useful tool in assessing treatment response in iron overload states.     

Intraductal papillary mucinous neoplasms of the pancreas: Correlation of helical CT features with pathologic findings

Objective

To evaluate the CT features of intraductal papillary mucinous neoplasms of the pancreas (IPMNs), and to compare with pathological findings in order to identify CT features that can be helpful in differentiating benign IPMNs from malignant IPMNs.

Materials and methods

The CT findings in 25 patients were reviewed for tumor location, tumor type, dilatation of the main pancreatic duct (MPD), MPD involvement, mural node or solid attenuating component, tumor size in branch duct or mixed duct type, dilatation of common bile duct (CBD) and invasion of surrounding structures. The data was subjected to Chi-Square Tests or Fisher's Exact Test using SPSS13.0 software with p value < 0.05 indicating significant statistical difference.

Results

Presence of mural node or solid enhancing component, size of mural node or solid enhancing component ≥7 mm, dilatation of CBD was more common in malignant IPMNs (p < 0.05). None of tumor location, tumor type, dilatation of MPD, MPD involvement, tumor size, and invasion of surrounding structures was statistically significant in differentiating benign from malignant IPMNs.

Conclusions

CT features suggestive of malignant or invasive IPMNs include presence of mural node or solid enhancing component, size of mural node or solid enhancing component ≥7 mm, and dilatation of CBD.     

Radiocontrast media-associated exanthema: identification of cross-reactivity and tolerability by allergologic testing

Background

All iodinated radiocontrast media (RCM) may cause hypersensitivity reactions, either immediate-type within 5-10 min of RCM injection or delayed-type, which become apparent more than 1 h after RCM exposure. Delayed-type hypersensitivity to RCM may pose a problem for future radiologic investigations because due to possible immunological cross-reactivity all iodinated RCM are usually avoided.

Objective

The aim of this study was not only to identify the causal RCM for the exanthema but also to demonstrate that patients may receive alternative iodinated RCM despite a history of RCM-induced allergic exanthema.

Methods

We evaluated 32 patients with a history of exanthema after RCM application using standardized patch, prick and intradermal skin testing. In case of positive skin tests intravenous challenges with skin-test-negative RCM were performed to identify non-ionic monomer RCM which are tolerated.

Results

In 6 out of 32 patients skin tests strongly suggested a delayed-type non-IgE-mediated allergic hypersensitivity to the RCM iomeprol (3 x), iopromide (2×), and iopamidol. In 4 patients alternative non-ionic monomer RCM (2× iosarcol, iopromide, and iomeprol) were identified by controlled challenge tests.

Conclusions

The evaluation of patients with RCM-associated exanthema should always include appropriate skin tests ensuring that patients with a delayed-type allergic RCM-induced exanthema are not missed. Moreover, allergologic testing may identify alternative RCM of the group of non-ionic monomers, which are tolerated in future radiologic investigations.     

Phantom-less QCT BMD system as screening tool for osteoporosis without additional radiation

Purpose

Phantom-less bone mineral density (PLBMD) systems are easily integrated into the CT workflow for non-dedicated Quantitative CT (QCT) BMD measurements in thoracic and abdominal scans. This in vivo retrospective study aims to determine accuracy and precision of the PLBMD option located on the Extended Brilliance Workspace (Philips Medical Systems, Cleveland, OH, US) from both cross-sectional and longitudinal image data.

Materials and methods

The cross-sectional comparison with phantom-based QCT BMD was performed for 82 patients (61 female, 21 male) with a mean age of (63.0 ± 11.8 SD) years on 197 vertebrae. This was followed by an interobserver variability analysis on 71 vertebrae. The longitudinal PLBMD study was carried out on 45 vertebrae from 10 patients (5 female, 5 male) with a mean age of (64.4 ± 11.5 SD) years. They were re-scanned with standardized scan and contrast-injection protocols within a mean and median of (33 ± 41 SD) and 8 days, respectively. All CT scans were acquired on an Mx8000 Quad (Philips) at Florence-Nightingale Hospital, Kaiserswerth, Germany, in a spiral acquisition mode.

Results

A negligible BMD bias of −0.9 mg/cm³ for the PLBMD option was observed with respect to phantom-based QCT BMD. Applying CT number matching of muscle and fat ROIs, the analysis of cross-sectional interobserver and of longitudinal variability yielded precision values of 3.1 mg/cm³ (CV% = 4.0) and 4.2 mg/cm³ (CV% = 5.3), respectively.

Conclusion

Although the precision is inferior to phantom-based BMD systems, PLBMD is a robust clinical utility for the detection of lowered BMD in a large patient population. This can be achieved without additional radiation exposure from non-contrasted CT scans, to perform an ancillary diagnosis of osteopenia or osteoporosis.     

Dual-source computed tomography: Estimation of radiation exposure of ECG-gated and ECG-triggered coronary angiography

Purpose

The aim of the study was to estimate radiation exposure of coronary calcium scoring and angiography using ECG-gated and ECG-triggered dual-source computed tomography.

Materials and methods

An Alderson Rando phantom equipped with thermoluminescent dosimeters was used for all dose measurements. Effective dose was calculated according to ICRP 103. Radiation exposure was performed on a dual-source computed tomography (DSCT) scanner with standard protocols for calcium scoring (DSCT-Ca) and coronary angiography (DSCTA) at different heart rates (40-100 beats/min). Furthermore, a scanning protocol with ECG-triggering as well as a standard chest CT scan were evaluated.

Results

Depending on gender, heart rate and ECG-pulsing, the effective dose of a complete cardiac DSCT (DSCT-Ca and DSCTA) scan varies from 10.2 to 32.6 mSv. The effective radiation dose increased significantly with lower heart rates (p < 0.035). ECG-pulsing reduced the radiation exposure significantly in DSCTA (p < 0.001). Due to breast tissue in the primary scan range, females’ doses showed an increase up to 69.9% compared to males in scan protocols without ECG-pulsing. Prospective ECG-triggered DSCTA resulted in estimated effective doses from 2.8 mSv (males) to 4.1 mSv (females).

Conclusion

The ECG-pulsing technique has proven its effectiveness to reduce effective dose in coronary CT angiography and is recommended for all patients with regular heart rates. The patient's heart rate influences the radiation exposure with a significant decrease at higher heart rates. Due to its lower dose, ECG-triggered DSCTA should be implemented for special indications, i.e. for diagnosis of pathologies of the aortic root and the ascending aorta.