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- Acosta Ruiz, Vanessa, 1987-, et al.
(författare)
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Microwave ablation of 105 T1 renal tumors : technique efficacy with a mean follow-up of two years
- 2024
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Ingår i: Acta Radiologica. - : Sage Publications. - 0284-1851 .- 1600-0455. ; 65:3, s. 294-301
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Tidskriftsartikel (refereegranskat)abstract
- Background: Thermal ablation (TA) with radiofrequency (RFA) or cryoablation (CA) are established treatments for small renal masses (≤4 cm). Microwave ablation (MWA) has several potential benefits (decreased ablation time, less susceptibility to heat-sink, higher lesion temperatures than RFA) but is still considered experimental considering the available small-sample studies with short follow-up.Purpose: To evaluate technique efficacy and complications of our initial experience of renal tumors treated using percutaneous MWA with a curative intent.Material and Methods: A total of 105 renal tumors (in 93 patients) were treated between April 2014 and August 2017. MWA was performed percutaneously with computed tomography (CT) guidance under conscious sedation (n=82) or full anesthesia. Patients were followed with contrast-enhanced CT scans at six months and yearly thereafter for a minimum of five years. The mean follow-up time was 2.1 years. The percentage of tumors completely ablated in a single session (primary efficacy rate) and those successfully treated after repeat ablation (secondary efficacy rate) were recorded. Patient and tumor characteristics as well as complications were collected retrospectively.Results: The median patient age was 70 years and median tumor size was 25 mm. Primary efficacy rate was 96.2% (101/105 tumors). After including two residual tumors for a second ablation session, secondary efficacy was 97.1% (102/105). Periprocedural complications were found in 5.2% (5/95) sessions: four Clavien-Dindo I and one Clavien-Dindo IIIa. One postprocedural Clavien-Dindo II complication was found.Conclusion: MWA has high efficacy rates and few complications compared to other TA methods at a mean follow-up of two years.
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| 3. |
- Acosta Ruiz, Vanessa, et al.
(författare)
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Predictive factors for complete renal tumor ablation using RFA
- 2016
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 57:7, s. 886-893
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Radiofrequency ablation (RFA) can be used to treat renal masses in patients where surgery is preferably avoided. As tumor size and location can affect ablation results, procedural planning needs to identify these factors to limit treatment to a single session and increase ablation success.PURPOSE: To identify factors that may affect the primary efficacy of complete renal tumor ablation with radiofrequency after a single session.MATERIAL AND METHODS: Percutaneous RFA (using an impedance based system) was performed using computed tomography (CT) guidance. Fifty-two renal tumors (in 44 patients) were retrospectively studied (median follow-up, 7 months). Data collection included patient demographics, tumor data (modified Renal Nephrometry Score, histopathological diagnosis), RFA treatment data (electrode placement), and follow-up results (tumor relapse). Data were analyzed through generalized estimating equations.RESULTS: Primary efficacy rate was 83%. Predictors for complete ablation were optimal electrode placement (P = 0.002, OR = 16.67) and increasing distance to the collecting system (P = 0.02, OR = 1.18). Tumor size was not a predictor for complete ablation (median size, 24 mm; P = 0.069, OR = 0.47), but all tumors ≤2 cm were completely ablated. All papillary tumors and oncocytomas were completely ablated in a single session; the most common incompletely ablated tumor type was clear cell carcinoma (6 of 9).CONCLUSION: Optimal electrode placement and a long distance from the collecting system are associated with an increased primary efficacy of renal tumor RFA. These variables need to be considered to increase primary ablation success. Further studies are needed to evaluate the effect of RFA on histopathologically different renal tumors.
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| 5. |
- Acosta Ruiz, Vanessa, 1987-, et al.
(författare)
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Split renal function after treatment of small renal masses : comparison between radiofrequency ablation and laparoscopic partial nephrectomy.
- 2021
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Ingår i: Acta Radiologica. - : Sage Publications. - 0284-1851 .- 1600-0455. ; 62:9, s. 1248-1256
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Radiofrequency ablation (RFA) and laparoscopic partial nephrectomy (LPN) are used to treat small renal masses (SRM; ≤4 cm), although there are conflicting results in the changes in creatinine and estimated glomerular filtration rate (eGFR) after treatment. On contrast-enhanced computed tomography (CE-CT) images, the quantity and quality of renal function can be evaluated by calculating the split renal function (SRF).PURPOSE: To compare renal function after RFA or LPN treatment of SRMs through evaluation of the SRF in the affected kidney.MATERIAL AND METHODS: Single T1a renal tumors successfully treated with RFA (n = 60) or LPN (n = 31) were retrospectively compared. The SRF was calculated on pre-treatment CE-CT images and the first follow-up exam after completed treatment. Serum creatinine and eGFR values were collected simultaneously. To compare renal function outcomes, Student's t-test and multivariable linear regression models (adjusted to RFA/LPN treatment, pre-treatment SRF/eGFR, BMI, age, tumor characteristics, and Charlson Comorbidity Index) were used.RESULTS: SRF was reduced in both groups, although reduction was greater in the LPN group (LPN -5.7%) than in the RFA group (RFA -3.5%; P = 0.013). After adjusted analysis, the LPN group still had greater SRF reduction (difference 3.2%, 95% confidence interval 1.3-1.5; P = 0.001). There was no difference between groups in the change of creatinine/eGFR after treatment.CONCLUSION: Both RFA and LPN are nephron-sparing when treating SRMs. However, in this series, reduction of SRF in the affected kidney was smaller after RFA, having a more favorable preservation of renal function than LPN.
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| 6. |
- Ahnfelt, Anders, et al.
(författare)
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Accuracy of iodine quantification using dual-energy computed tomography with focus on low concentrations.
- 2022
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 63:5, s. 623-631
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Iodine quantification using dual-energy computed tomography (DECT) is helpful in characterizing, and follow-up after treatment of tumors. Some malignant masses, for instance papillary renal cell carcinomas (p-RCC), are hard to differentiate from benign lesions because of very low contrast enhancement. In these cases, iodine concentrations might be very low, and it is therefore important that iodine quantification is reliable even at low concentrations if this technique is used.PURPOSE: To examine the accuracy of iodine quantification and to determine whether it is also accurate for low iodine concentrations.MATERIAL AND METHODS: Twenty-six syringes with different iodine concentrations (0-30 mg I/mL) were scanned in a phantom model using a DECT scanner with two different kilovoltage and image reconstruction settings. Iodine concentrations were measured and compared to known concentration. Absolute and relative errors were calculated.RESULTS: For concentrations of 1 mg I/mL or higher, there was an excellent correlation between true and measured iodine concentrations for all settings (R = 0.999-1.000; P < 0.001). For concentrations <1.0 mg I/mL, the relative error was greater. Absolute and relative errors were smaller using tube voltages of 80/Sn140 kV than 100/Sn140 kV (P < 0.01). Reconstructions using a 3.0-mm slice thickness had less variance between repeated acquisitions versus 0.6 mm (P < 0.001).CONCLUSION: Iodine quantification using DECT was in general very accurate, but for concentrations < 1.0 mg I/mL the technique was less reliable. Using a tube voltage with larger spectral separation was more accurate and the result was more reproducible using thicker image reconstructions.
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| 7. |
- Dahlman, Pär, et al.
(författare)
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CT of the kidneys : what size are renal cell carcinomas when they cause symptoms or signs?
- 2007
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Ingår i: Scandinavian Journal of Urology and Nephrology. - : Informa UK Limited. - 0036-5599 .- 1651-2065. ; 41:6, s. 490-495
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To investigate the size of renal cell carcinomas (RCCs) when they cause macroscopic hematuria or other symptoms and/or signs. Material and methods. A retrospective review of 232 patients (136 males, 96 females; mean age 68±11 years; age range 40–90 years) with a diagnosis of RCC was undertaken. Patients were grouped according to the presenting symptoms and/or signs caused by the RCCs. Tumor size was measured on CT images. Results. Of the RCCs, 29% were found incidentally and 71% caused symptoms and/or signs. The incidentally found RCCs measured 4.9±2.6 cm (range 2–12 cm) and RCCs causing symptoms and signs measured 8.9±3.2 cm (range 3–18 cm); this size difference was significant (p<0.001). None of the RCCs causing macroscopic hematuria were <4 cm in size and only 3/165 (2%) of the symptomatic RCCs were <4 cm in size. Discussion. If small (<4 cm) RCCs do not cause symptoms, patients with them will not be referred for CT or any other imaging modality. Therefore, if a 2-cm RCC is found in a patient presenting with macroscopic hematuria, it is unlikely that this small RCC caused the hematuria and another cause of the hematuria must be ruled out.
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| 8. |
- Dahlman, Pär
(författare)
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CT Urography : Efforts to Reduce the Radiation Dose
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Computed tomography urography (CTU) is today the imaging method used to investigate patients with suspected urinary tract malignancy, replacing the old imaging method intravenous pyelography (IVP) about a decade ago. The downside of this shift was that the effective radiation dose to the examined patient was eight times higher for CTU compared to IVP. Based on four different studies, the present thesis focused on efforts to reduce the CTU radiation dose. In study I, the number of cysts and solid lesions in the separate scan phases was evaluated in 57 patients undergoing four-phase CTU 1997-98. The number of scans was reduced from four to three when the nephrographic scan was abolished following study I.Study II registered the diameter of renal cell carcinoma (RCC) and the presenting symptoms in the total number of patients (n=232) diagnosed with RCC between 1997 and 2003. The results from study II showed that the critical size for RCCs to cause macroscopic hematuria was ≥ 4 cm. Study III was a dose-escalation study aimed to decide the minimal possible tube load in the unenhanced and excretory phase scans if the low dose images are reviewed together with normal dose corticomedullary phase images. Study III showed that it is possible to reduce the mean effective dose in three phase CTU from 16.2 mSv to 9.4 mSv with a combined low and normal dose CTU protocol. Study IV investigated the changes in the CTU protocol between 1997 and 2008, and the development of the effective radiation dose. Study IV clarified how the CTU protocol has changed between 1997 and 2008 and as a result the mean effective radiation dose to patients undergoing CTU in 2008 is only 39% of the effective dose in 1997. In conclusion, the findings from the studies included in this thesis have contributed to a reduced radiation dose to patients undergoing CTU. The mean effective dose from CTU is at present only three times higher compared to that from the IVP.
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| 9. |
- Dahlman, Pär, et al.
(författare)
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Detection and characterisation of renal lesions by multiphasic helical CT.
- 2000
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 41:4, s. 361-366
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The fast helical CT technique allows examination of the kidneys during different phases of contrast medium enhancement. However, every additional phase increases the radiation dosage to the patients. We investigated the detection rate and characterisation of renal lesions during different phases and evaluated them separately, and considered the possibility of excluding phases without loss of important information. MATERIAL AND METHODS: Sixty patients who underwent contrast-enhanced multiphasic renal helical CT examination were included. Every CT phase was evaluated separately. The number of lesions and the characteristics of the lesions were noted and all lesions were viewed together. RESULTS: A total of 153 cysts and 17 solid lesions were detected. The largest and an equal number of cysts (142/143) was detected in the nephrographic and excretory phases. However, the nephrographic phase detected more cortical cysts and the excretory phase detected more sinus cysts. All solid lesions were detected in all phases. Renal parenchymal tumours were best characterised in the cortical phase and angiomyolipomas in the native phase. CONCLUSION: The cortical phase was best for characterisation of renal parenchymal tumours. The nephrographic and excretory phases were best in detecting and characterising renal cysts. The nephrographic phase was the phase giving the least diagnostic information.
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| 10. |
- Dahlman, Pär, et al.
(författare)
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How Much Dose Can Be Saved in Three-Phase CT Urography? A Combination of Normal-Dose Corticomedullary Phase With Low-Dose Unenhanced and Excretory Phases
- 2012
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Ingår i: American Journal of Roentgenology. - 0361-803X .- 1546-3141. ; 199:4, s. 852-860
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE:The purpose of this study was to investigate the degree to which the total radiation dose for CT urography can be lowered by selective reduction of the dose in the unenhanced and excretory phases when images in these phases are systematically evaluated alongside normal-dose corticomedullary phase images.SUBJECTS AND METHODS:Twenty-seven patients (mean age, 74 ± 9 years) underwent single-bolus CT urography with acquisition in the unenhanced, corticomedullary, and 5-minute excretory phases. The scanning parameters for normal-dose CT urography were as follows: 16 × 0.75 mm, 120 kV, and automatic exposure control technique reference tube loads of 100, 120, and 100 effective mAs (mAseff). The patients also underwent low-dose unenhanced and excretory phase scanning, in which the dose was escalated stepwise from a volume CT dose index (CTDIvol) of 1.7 to 6.6 mGy (reference 20-40-60-80 mAseff). Images were analyzed for quality and diagnostic confidence. If low-dose scans of three patients were inadequate, the study continued to the next dose level. When 20 patients were successfully included in the unenhanced and excretory phase groups, the study ended. Doses were calculated with a CT patient dosimetry calculator.RESULTS:Combined with the normal dose for corticomedullary phase scanning, doses of CTDIvol 1.5 mGy for the unenhanced phase and CTDIvol 2.7 mGy for the excretory phase were sufficient. The effective dose for three-phase CT urography was lowered from 16.2 to 9.4 mSv, a decrease of 42%. Diagnostic confidence in low-dose images was equal to that in normal-dose images when low-dose unenhanced and excretory phase images were read along-side normal-dose corticomedullary phase images.CONCLUSION:With a three-phase CT urographic protocol, significant dose reductions in the unenhanced and excretory phases can be achieved when these phases are combined with a normal-dose corticomedullary phase.
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