Comparative Analysis of Cone-Beam CT Angiogram and Conventional CT Angiogram for Prostatic Artery Identification Prior to Embolization

Pre-prostatic artery embolization (PAE) cone-beam computed tomography (CT) angiograms (n = 31; mean age: 62.4 ± 9.75 years) and conventional CT angiograms (n = 32; mean age: 62.5 ± 7.2 years) were retrospectively compared. Mean signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), radiation exposure, and prostatic artery (PA) identification scores (0–4) for cone-beam CT angiogram and conventional CT angiogram were 33.19 (± 14.31) and 18.13 (± 5.38) (P < .01); 27.42 (± 13.39) and 14.78 (± 4.92) (P < .01); 14.57 mSv (±2.5) and 19.25 mSv (±3.7) (P < .01); 3.36 (± 0.89) and 3.16 (± 0.95) (P = .08), respectively. Pre-PAE cone-beam CT angiogram allows for PA identification with improved SNR and CNR and less radiation dose compared to conventional CT angiogram.     

Is MRI equivalent to CT in the guidance of TAVR? A pilot study

Objectives

To compare a comprehensive cardiovascular magnetic resonance imaging (MRI) protocol with contrast-enhanced computed tomography angiography (CTA) for guidance in transcatheter aortic valve replacement (TAVR) evaluation.

Methods and results

Non-contrast three-dimensional (3D) ‘whole heart’ MRI imaging for aortic annulus sizing and measurements of coronary ostia heights, contrast-enhanced MRI angiography (MRA) for evaluation of transfemoral routes as well as aortoiliofemoral-CTA were performed in 16 patients referred for evaluation of TAVR. Aortic annulus measurements by MRI and CTA showed a very strong correlation (r=0.956, p<0.0001; effective annulus area for MRI 430±74 vs. 428±78 mm² for CTA, p=0.629). Regarding decision for valve size there was complete consistency between MRI and CTA. Moreover, vessel luminal diameters and angulations of aortoiliofemoral access as measured by MRA and CTA showed overall very strong correlations (r= 0.819 to 0.996, all p<0.001), the agreement of minimal vessel diameter between the two modalities revealed a bias of 0.02 mm (upper and lower limit of agreement: 1.02 mm and -0.98 mm).

Conclusions

In patients referred for TAVR, MRI measurements of aortic annulus and minimal aortoiliofemoral diameters showed good to excellent agreement. Decisions based on MRI measurements regrading prosthesis sizing and transfemoral access would not have modified TAVR-strategy as compared to a CTA-based choice.

Key Points

? ‘Whole heart’ MRI and CTA measurements of aortic annulus correlate very strongly. ? MRI- and CTA-based prostheses sizing are in excellent agreement. ? MRA and CTA equally guide TAVR access strategy.

     

Does ultra-low-dose CT with a radiation dose equivalent to that of KUB suffice to detect renal and ureteral calculi?

The objective of this study was to evaluate the diagnostic yield of multislice CT using a radiation dose equivalent to that of conventional abdominal x-ray (KUB). One hundred forty-two patients were prospectively examined with ultrasound and a radically dose-reduced CT protocol (120 kV, 6.9 eff. mAs). Number and size of calculi, presence of urinary obstruction, and alternative diagnoses were recorded and confirmed by stone removal/discharge or by clinical and imaging follow-up. The mean effective whole-body dose was 0.5 mSv in men and 0.7 mSv in women. The sensitivity and specificity in detecting patients with calculi was 97% and 95% for CT and 67% and 90% for ultrasound. Urinary obstruction was similarly assessed, whereas CT identified significantly more alternative diagnoses than ultrasound (P<0.001). With regard to published data for standard-dose CT, the present CT protocol seems to be comparable in its diagnostic yield in assessing patients with calculi, and its radiation dose is equivalent to that of KUB.     

CT scanning of middle ear cholesteatoma: what does the surgeon want to know?

The history of surgery for middle ear cholesteatoma is of an evolution of techniques to meet the challenges of inaccessible disease and of post-operative cavity management. The concept has traditionally been of exploration guided by awareness and anticipation of all, possibly asymptomatic, complications. Modern imaging reliably demonstrates surgical anatomy, dictating the ideal approach, forewarns of complications and may reveal the extent of disease. An apparent resistance amongst otologists to universal CT scanning prior to mastoidectomy contrasts with the enthusiasm of skull base surgeons or rhinologists for appropriate imaging.     

Does CT of thymic epithelial tumors enable us to differentiate histologic subtypes and predict prognosis?

OBJECTIVE: The aims of our study were to describe the CT findings of thymic epithelial tumors and to correlate these findings with the histopathologic subtypes and prognosis. MATERIALS AND METHODS: The CT findings of thymic epithelial tumors were analyzed in 91 patients who had undergone surgery between May 1995 and June 2002. Two observers, who were unaware of the histopathologic classification made in accordance with World Health Organization (WHO) recommendations and the prognosis of the tumors, retrospectively reviewed the initial CT findings in terms of the contours and shapes of the tumors and the presence of necrosis, calcification, mediastinal fat or great vessel invasion, pleural seeding, contrast enhancement, and lymph node enlargement. These findings were compared with the simplified subgroups of WHO histologic classification (low-risk thymomas [types A, AB, and B1], high-risk thymomas [types B2 and B3], and thymic carcinomas [type C]) and with postoperative recurrence. RESULTS: The study found 31 low-risk thymomas (eight type A, 16 type AB, and seven type B1 tumors), 45 high-risk thymomas (25 type B2 and 20 type B3), and 15 thymic carcinomas (type C). Lobulated contour was more often seen in high-risk thymomas (26/45, 58%; p = 0.0456) and thymic carcinomas (10/15, 67%; p = 0.033) than in low-risk thymomas (9/31, 29%). Mediastinal fat invasion was more often seen in thymic carcinomas (5/15, 33%; p = 0.0133) than in low-risk thymomas (1/31, 3%). Great vessel invasion was seen only in thymic carcinomas (2/15, 13%; p = 0.0244). Tumors with a lobulated or irregular contour, an oval shape, mediastinal fat or great vessel invasion, and pleural seeding showed significantly more frequent recurrence and metastasis (all, p < 0.05). CONCLUSION: Although CT is of limited value in differentiating histologic subtypes according to the WHO classification, CT findings may serve as predictors of postoperative recurrence or metastasis for the thymic epithelial tumors.     

Increased Susceptibility to β-irradiation of Senescent Mouse Skin Irrespective of Grafting to Young Recipients

To evaluate the influence of inhibitors of DNA synthesis/repair on the yield of chromosomal aberrations in the G₂ phase of the cell cycle, whole-blood cultures of human lymphocytes were exposed to various doses of fission neutrons or X-rays and treated post-irradiation during the last 2·45 h before harvesting, with 5 mm caffeine, 5 mm hydroxyurea (HU) and 0·05 mm cytosine arabinoside (ara-C). The presence of caffeine and HU strongly potentiated the yield of chromatid-type aberrations induced by both neutrons and X-rays. No potentiating effect, except at the highest dose of neutrons, was observed when irradiated cells were subsequently treated with ara-C. Since ara-C strongly potentiated the frequency of chromatid aberrations induced in G₂ lymphocytes by X-rays, the results presented here indicate that fission neutrons produce a smaller proportion of lesions, the repair of which can be inhibited by ara-C, compared with the number produced by X-rays. In addition, neutron-induced mitotic delay was shortened by treatment with caffeine, mainly within the first 2 h after irradiation.     

CT Volumetric Assessment of Pulmonary Neoplasms after Radiofrequency Ablation: When to Consider a Second Intervention?

PurposeTo determine the minimal follow-up time point to predict therapeutic response to radiofrequency (RF) ablation of lung tumors.Materials and MethodsA retrospective study design was approved by the institutional review board. From January 2008 to January 2010, 78 patients (46 men and 32 women; mean age, 58.9 y) underwent computed tomography (CT)–guided percutaneous RF ablation of pulmonary malignancies. A single RF multitined electrode was used to treat 100 index tumors, 6 primary lesions, and 94 metastatic lesions. CT volumetric measurements of ablated tumors were made before ablation and 24 hours, 3–6 weeks, 3 months, 6 months, 9 months, and 12 months after ablation. An unpaired t test and Spearman rank correlation coefficient were used to analyze the volumetric changes.ResultsComplete successful ablation was achieved in 80% of index tumors. The mean time to detection of tumor residue or recurrence tumor residue or recurrence was 6.7 months after ablation. In successfully ablated lesions, the mean volume before ablation was 1.81 cm³ (standard deviation [SD], 1.71); in failed ablation lesions, the mean volume before ablation was 2.58 cm³ (SD, 2.8) (P = .42). The earliest statistically significant follow-up time point that showed a difference in the volumetric measurements of failed and successful ablations as well as the earliest significant correlation with the 12-month point was 3 months (P = .025, Spearman R = 0.72). Secondary tumor control after repeat ablation was statistically significant for lesions ablated at a 3-month interval (four out of five lesions) (P = .04).ConclusionsCT volumetric assessment of ablated tumors revealed that 3 months was the earliest time point that may determine the response of a pulmonary ablation or repeat intervention.     

Can virtual non-enhanced CT be used to replace true non-enhanced CT for the detection of palpable cervical lymph nodes? A preliminary study

Purpose

To investigate the potential of virtual non-contrast CT (VNCT) from dual-energy CT to replace true nonenhanced CT (TNCT) for the detection of enlarged cervical lymph nodes.

Materials and methods

Thirty-nine patients with 94 histopathologically proven cervical lymph nodes were imaged with the dual-energy CT technique. VNCT images from the arterial [VNCT-A] and venous phases [VNCT-V] were obtained with the liver VNC application. The mean CT number and signal-to-noise ratio (SNR) were compared. Image quality was evaluated with a score scale of 1–5. Effective dose (ED) was calculated and compared.

Results

Mean CT numbers of cervical lymph nodes were higher on VNCT than on TNCT (P = 0.034). There was no difference in the SNR among three sets of non-enhanced CT images, but the CNR of VNCT images was higher than that of TNCT images (P < 0.001). Image quality of VNCT from two phases was comparable to that of TNCT (P = 0.070). There was no difference in image quality of three sets of non-enhanced CT images (P > 0.05). ED from dual-phase dual-energy CT was lower than that from tri-phase CT scans (P < 0.001).

Conclusion

VNCT images from dual-energy CT of the neck had diagnostic image quality; they have the potential to replace TNCT, thus reducing the radiation dose.     

Diagnostic value of CT compared to ultrasound in the evaluation of acute abdominal pain in children younger than 10 years old

To assess the diagnostic value of ultrasound compared to CT in evaluating acute abdominal pain of different causes in children 10 years of age and under, hospital records and imaging files of 4052 patients under age of 10 who had imaging for abdominal pain were reviewed. One-hundred-thirty-two patients (3 %), (74 males/58 females) who underwent ultrasound and CT within 24 h were divided by age: group I, ages 0–48 months (25 patients); group II, 49–84 months (53 patients); and group III, 85–120 months (54 patients). Diagnoses at ultrasound, CT, and discharge were compared. Cases of a change in diagnosis following CT and impact of the changed diagnosis on patient management were assessed. Non-diagnostic ultrasound or a diagnostic conundrum was present in a small percentage (3 %) of our patients. In the group of patients imaged with two modalities, CT changed the diagnosis in 73/132 patients (55.3 %). Patient management changed in 63/132 patients (47.7 %). CT changed the diagnosis in 46/64 patients with surgical conditions (71.8 %, p?<?0.001). Among patients with surgical conditions, the difference between ultrasonography (US) and CT diagnoses was significant in groups 2 (p?=?0.046) and 3 (p?=?0.001). The impact of the change in diagnosis in surgical patients imaged with two modalities was significant in the group as a whole and in each age group separately. Non-diagnostic or equivocal US in a small percentage of patients is probably sufficient to justify the additional radiation burden.     

Does catheter shape influence the success of right adrenal venous sampling? The interaction of catheter shape to anatomical factors on CT

Purpose

To evaluate the importance of selecting an appropriate catheter shape for the right adrenal vein (RAV) anatomy on CT to the success of right adrenal venous sampling (RAVS) by elucidating the interactions of anatomical factors with catheter shape.

Materials and methods

130 patients with enhanced CT underwent RAVS using two catheters: catheter 1 was planar and catheter 2 was a three-dimensional shape. The following anatomical factors on CT were evaluated in each patient: presence of a right adrenal tumor, presence of a common trunk with an accessory right hepatic vein, diameter of the RAV, short and long diameters of the IVC, ratio of the long to the short diameter of IVC, and the transverse, modified transverse, and vertical angles of the RAV. RAVs were classified by direction on CT as lateral–caudal, lateral–cranial, medial–caudal, or medial–cranial. The technical feasibility of each catheter was evaluated by intragroup analysis.

Results

108 patients underwent technically successful RAVS with one or both catheters. Eight of the 22 patients in whom RAVS was not successfully achieved by either catheter within ten minutes required microcatheters; other catheters were used in the other 14. The factors that were found to be associated with RAVS success were the modified transverse and the vertical angles (p < 0.01) of RAV on CT. Catheters 1 and 2 provided stable sampling in the lateral–caudal and medial groups, respectively.

Conclusion

Adapting the shape of the catheter to the anatomy of the RAV can make RAVS more feasible. The anatomical factors that were found to be associated with RAVS success were the transverse angle modified by the IVC axis as well as the vertical angle of RAV on CT.