Mikael Hellström

Contrast-Medium-Induced Nephropathy Correlated to the Ratio Between Dose in Gram Iodine and Estimated GFR in ml/min

Purpose: To suggest a more precise tool when assessing the risk of contrast-medium-induced nephropathy (CIN), i.e. the ratio between contrast medium (CM) dose expressed in grams of iodine (g-I) and estimated glomerular filtration rate in ml/min (eGFR; based on equations using serum-creatinine (s-Cr), weight, height, age, and/or sex), here named I-dose/GFR ratio. Material and Methods: A Medline search of published CIN investigations reporting mean eGFR and mean dose of low-osmolality CM (LOCM) identified 10 randomized controlled prophylactic and 2 cohort coronary investigations, and 3 randomized and 1 cohort computed tomographic (CT) investigation. From the randomized trials, data were collected only from the placebo or control arms, unless there was no significant difference between the control and test groups. The mean I-dose/GFR ratio of each study was correlated with the mean frequency of CIN-1 (s-Cr rise⩾44.2 µmol/l or ⩾20–25%) and CIN-2 (oliguria or requiring dialysis). A maximum dose according to an I-dose/GFR ratio = 1 in patients with s-Cr ranging from 100 to 300 µmol/l was compared with that of Cigarroas formula and with a “European consensus” threshold published by the European Society of Urogenital Radiology, both using s-Cr alone to predict renal function. McCulloughs formula was used to assess the risk of CIN requiring dialysis at an I-dose/GFR ratio = 1 with LOCM. Results: The coronary investigations revealed a linear correlation with a correlation coefficient between the I-dose/GFR ratio and the frequency of CIN-1 and CIN-2 of 0.91 (P<0.001) and 0.84 (P = 0.001), respectively. At a mean I-dose/GFR ratio = 1, the regression line indicated a 10% risk of CIN-1 and a 1% risk of CIN-2. At a mean I-dose/GFR ratio = 3, the risk of CIN-1 and CIN-2 increased to about 50% and 15%, respectively. Pooled weighted data from the CT investigations revealed a 12% risk of CIN-1 at a mean I-dose/GFR ratio = 1.1 and no cases of CIN-2. The maximum CM dose according to an I-dose/GFR ratio = 1 was about 30–50% of that of both Cigarroas formula and the “European consensus” in elderly low-weight individuals, while it was similar for middle-aged individuals weighing about 90 kg. McCulloughs formula suggests that there will be an exponentially increasing risk of CIN requiring dialysis, but at an I-dose/GFR ratio = 1 and using LOCM it will not exceed 1% until GFR decreases below 30 ml/min in diabetics and below 20 ml/min in non-diabetics. Conclusion: Using the I-dose/GFR ratio may be a more expedient way of improving risk assessment of CIN than todays common practice of estimating CM dose from volume alone and renal function from s-Cr alone. Prospective studies based on individual patient data are encouraged to define the risk of CIN at various I-dose/GFR ratios and correlated to type of CM, examination, risk factors, etc.

Adrenal lesion frequency: A prospective, cross-sectional CT study in a defined region, including systematic re-evaluation

Background: Incidentally detected adrenal lesions have become a growing clinical problem. Purpose: To prospectively estimate and validate the prevalence of incidentally detected adrenal lesions (adrenal incidentaloma) in patients with or without malignant disease undergoing CT. Material and Methods: During 18 months all adult patients with incidentally discovered adrenal lesions detected at CT were prospectively reported from the radiology departments of all hospitals in Western Sweden (1.66 million inhabitants). Frequencies of adrenal lesions initially reported at CT and at a systematic re-evaluation were compared. The interobserver variation in blindly assessing adrenal lesions was also analyzed. Results: Adrenal lesions were reported and verified in 339 patients (193 females; mean age 69 years, range 30–94 years). Mean lesion size was 25.8 mm (range 8–94 mm). The mean frequency of originally reported adrenal lesions was 0.9% (range 0–2.4% between hospitals). The systematic re-evaluation of 3801 randomly selected cases showed a mean frequency of 4.5% (range 1.8–7.1% between hospitals). The re-evaluation revealed 177 cases with adrenal lesions, 30% of these were submitted by the local radiologist in accordance with the study design, 23% were described in the local radiology report but not submitted to the study center, while 47% were neither locally reported nor submitted. Conclusion: Adrenal lesions are under-reported in clinical practice. Prevalence figures for adrenal incidentalomas should therefore be interpreted with caution, especially in multi-center settings.

SPONDYLOLYSIS AND THE SACRO-HORIZONTAL ANGLE IN ATHLETES

The frequency of spondylolysis and the relationship between spondylolysis and the sacro-horizontal angle in 143 athletes and 30 non-athletes is reported. Athletes had a larger sacro-horizontal angle than non-athletes. The sacro-horizontal angle was larger in athletes with spondylolysis as compared with those without. An increased incidence of spondylolysis with an increased angle was demonstrated. It is suggested that an increased sacro-horizontal angle may predispose to spondylolysis, especially in combination with the high mechanical loads sustained in certain sports.

Ultrasound-guided percutaneous radiofrequency ablation of small renal tumors: Clinical results and radiological evolution during follow-up.

Background: Treatment of small renal masses with percutaneous radiofrequency ablation (RFA) is under development. Data are limited regarding the oncologic efficacy and complication rates of ultrasound (US)-guided RFA. Purpose: To retrospectively analyze results and factors predictive of incomplete ablation and local recurrence in patients treated for small renal tumors with US-guided percutaneous RFA. Material and Methods: Forty-one consecutive patients (27 males), mean 70 (40–86) years, with 44 tumors were included. Core biopsies were obtained before treatment. Follow-up was performed with CT or MRI. Tumor diameter, tumor volume, volume of the ablation zone, necrosis index, tumor location, distance from tumor to skin, and BMI were analyzed. Results: Biopsies showed malignancy in 72%, 10% were benign, and 18% were inconclusive. Thirty-six tumors (82%) were completely ablated after first RFA and 40 tumors (91%) after a second treatment. Mean follow-up was 27 months. Nine completely ablated tumors (23%) showed local recurrence during follow-up, six of them were retreated. Tumor size was significantly larger and mean necrosis index lower in tumors with incomplete ablation compared with those completely ablated initially. In tumors <30 mm, the initial complete ablation rate was 93% and the local recurrence rate during follow-up was 16% (4/25). Conclusion: US guidance is feasible for RFA of small renal tumors. However, thorough long-term follow-up appears mandatory, as a substantial proportion of the patients will develop late local recurrence and will need more than one RFA treatment session. Large tumor diameter and volume and a low necrosis index were predictive indicators of incomplete ablation after the first treatment.

Cardiac output measured by electrical velocimetry in the CT suite correlates with coronary artery enhancement: A feasibility study

Background: Cardiac output (CO) is inversely related to vascular contrast medium (CM) enhancement during computed tomography (CT). Impedance cardiography with a new technique, electrical velocimetry (EV), may create opportunities to measure CO pre-examination for adaptation of CM injection parameters. Purpose: To relate COEV measured by radiology staff to aortic attenuation as a measure of coronary artery attenuation during CT coronary angiography (CTCA), and to formulate a tentative statistical model to adapt CM injection parameters to CO. Material and Methods: COEV was measured immediately before 100 kVp CTCA (64-multirow detector) in 27 patients with presumed coronary artery disease. For CTCA, 260 mg I/kg (maximum dosage weight: 80/90 kg for women/men) was injected intravenously during 12 s. Simple linear regression analysis was performed to explore the correlation between aortic attenuation (Hounsfield units, HU) and body weight, the influence of COEV on aortic attenuation adjusted to injected CM dose rate (HU per mg I/kg/s), and to establish a tentative formula on how to adapt CM injection parameters to COEV and desired aortic attenuation. Results: The correlation between aortic attenuation and body weight was weak and non-significant (r=−0.14 after outlier exclusion). A significant negative correlation (r=−0.63) was found between aortic attenuation adjusted to injected CM dose rate (HU per mg I/kg/s) and COEV. The resulting formula, CM dose rate=COEV×(aortic attenuation−240)/55, made it possible to calculate CM volumes and injection rates at various COs and, for example, the present mean aortic attenuation (438 HU), injection time (12 s), CM concentration (320 mg I/ml), and a certain body weight. Conclusion: EV makes it possible to measure CO in the CT suite before vascular examinations. Hence, CM doses may be decreased in low CO states to reduce the risk of CM-induced nephropathy without jeopardizing diagnostic quality and may be increased in high CO states to avoid poor enhancement.

Survey update on implementation, indications, and technical performance of computed tomography colonography in sweden:

Background: Computed tomographic colonography (CTC) has gained increased acceptance in the last few years as a valid substitute for double-contrast barium enema (DCBE). However, implementation of new technologies is complex, since several factors may influence the process. Purpose: To evaluate the current situation in Sweden concerning implementation of CTC, as compared to a previous national survey in 2005. Material and Methods: In December 2008, a structured, self-assessed questionnaire regarding implementation and technical performance of CTC was mailed to all radiology departments in Sweden. In March 2009, departments who had not replied were contacted by e-mail or by telephone. All (100%, 119/119) departments answered the questionnaire. Results: CTC is currently performed in 50/119 (42%) departments, i.e., 18 additional departments compared to 2005. Twenty-three out of 60 (38%) responding departments stated that they intend to start to perform CTC in the near future. DCBE is currently performed in 77/119 (65%) departments, 12 departments less compared to 2005. The most common reasons for non-implementation of CTC are non-availability of spiral CT scanner (41%, 26/64) and/or multidetector-row CT scanner (39%, 25/64), and lack of doctors’ time (34%, 22/64). Only 3% (2/64) of departments are “awaiting further scientific documentation” on CTC, a significant reduction compared to 2005 (P=0.002). Until 2009, 59% (29/49) of CTC centers had performed more than 200 CTCs compared to 13% (4/32) of CTC centers in 2005. Intravenous contrast material is routinely administered in 86% (42/49), and carbon dioxide is used to distend the colon in 90% (44/49). Almost all radiology departments (93%, 93/100) currently believe that CTC will “absolutely” or “probably” replace barium enema in the future, while in 2005 only 56% (55/99) gave similar answers. Conclusion: The survey reflects a further transition process from DCBE to CTC, with attitudes of radiologists increasingly in favor of CTC, although DCBE is still performed by the majority of radiology departments. DCBE should be replaced by colonoscopy and CTC, but the transition requires both human and economic resources.

Effect of surgery vs observation: skeletal 5-year outcomes in a randomized trial of patients with primary HPT (the SIPH study)†

Mild primary hyperparathyroidism (PHPT) is known to affect the skeleton, even though patients usually are asymptomatic. Treatment strategies have been widely discussed. However, long‐term randomized studies comparing parathyroidectomy to observation are lacking. The objective was to study the effect of parathyroidectomy (PTX) compared with observation (OBS) on bone mineral density (BMD) in g/cm2 and T‐scores and on biochemical markers of bone turnover (P1NP and CTX‐1) in a prospective randomized controlled study of patients with mild PHPT after 5 years of follow‐up. Of 191 patients with mild PHPT randomized to either PTX or OBS, 145 patients remained for analysis after 5 years (110 with validated DXA scans). A significant decrease in P1NP (p < 0.001) and CTX‐1 (p < 0.001) was found in the PTX group only. A significant positive treatment effect of surgery compared with observation on BMD (g/cm2) was found for the lumbar spine (LS) (p = 0.011), the femoral neck (FN) (p < 0.001), the ultradistal radius (UDR) (p = 0.042), and for the total body (TB) (p < 0.001) but not for the radius 33% (Rad33), where BMD decreased significantly also in the PTX group (p = 0.012). However, compared with baseline values, there was no significant BMD increase in the PTX group, except for the lumbar spine. In the OBS group, there was a significant decrease in BMD (g/cm2) for all compartments (FN, p < 0.001; Rad33, p = 0.001; UDR, p = 0.006; TB, p < 0.001) with the exception of the LS, where BMD was stable. In conclusion, parathyroidectomy improves BMD and observation leads to a small but statistically significant decrease in BMD after 5 years. Thus, bone health appears to be a clinical concern with long‐term observation in patients with mild PHPT.

How to read and report CTC.

Owing to encouraging results achieved in the clinical practice, CT colonography (CTC) is being increasingly employed for the examination of the whole colon and rectum and is quickly becoming a widely accepted diagnostic technique that is replacing double contrast barium enema and appears a promising tool for colorectal cancer screening as well. The increasing number of symptomatic and asymptomatic patients undergoing CTC for both evaluation of symptoms and colorectal cancer screening, along with the growing availability of CTC facilities in most healthcare departments and imaging centres, requires that a sufficient number of radiologists be adequately trained in performing and interpreting CTC studies. Indeed, optimal performance of CTC depends on a number of factors, including the quality of colonic preparation (e.g. laxative bowel cleansing and optimised colonic distension), the CTC image acquisition protocol used, and reading approach and specific skills of radiologists for correct detection and interpretation of colonic findings. Consequently, dedicated training and expertise is key to obtain high sensitivity in lesion detection and reduce the number of false positives, thus ensuring an optimal clinical management of patients. To this purpose, dedicated training programmes are essential to teach and standardise not only the approach to CTC reading, but also reporting of colonic findings.

Incidental Findings in Multislice CT of the Body

In radiology, an incidental finding (“incidentaloma”) is an incidentally discovered mass or lesion, detected by CT or other modality performed for an unrelated reason. With high-resolution cross-sectional imaging, such findings are very frequent, and an everyday challenge for radiologists.

CT colonography: implementation, indications, and technical performance – a follow-up national survey

Background Computed tomography colonography (CTC) is an accepted complement or alternative to optical colonoscopy (OC) but its implementation is incompletely analyzed, and technical performance varies between centers. Purpose To evaluate implementation, indications, and technical performance of CTC in Sweden and to evaluate compliance to international guidelines. Material and Methods A structured, self-assessed questionnaire regarding implementation and technical performance of CTC was sent to all eligible radiology departments in Sweden. Eighty-six out of 89 departments replied. Comparisons were made with similar national surveys from 2004 and 2009. Results The number of centers performing CTC gradually increased from 23 in 2004 to 77 in 2016. In parallel, centers performing barium enema (BE) examinations have decreased from 89 in 2004 to 13 in 2016. Main reasons stated for still performing BE were lack of resources regarding CTC/OC. Main reasons for not performing CTC were lack of suitable software, lack of machine/reading time, and lack of experience. The majority of centers follow international CTC guidelines. An important exception is fecal tagging, which was implemented in only 63% of the centers. Incomplete OC remains a major indication for CTC, while preoperative CTC in colorectal cancer and follow-up after diverticulitis have emerged as new indications. Conclusion CTC today is well implemented in routine healthcare but still lacking in capacity. Indications have expanded over time, and most departments perform “state of the art” CTC, although fecal tagging is incompletely implemented.