Martin E. O’Malley

Detection of Urothelial Tumors: Comparison of Urothelial Phase with Excretory Phase CT Urography—A Prospective Study

PURPOSE To compare contrast material-enhanced computed tomographic (CT) urography 60 seconds after injection of contrast material (urothelial phase [UP]) after intravenous administration of a diuretic with the standard 5-minute delayed excretory phase (EP) in a high-risk population for upper tract tumors. MATERIALS AND METHODS Institutional review board approval and informed consent were obtained. Eighty CT urographic examinations in 77 patients known to have or at high risk for urothelial malignancy were included. After intravenous administration of a diuretic, dual-phase CT urography was performed at 60 seconds (UP) and 5 minutes (EP) after intravenous administration of contrast material. Two experienced abdominal radiologists independently interpreted each phase more than 1 month apart to minimize recall bias. Urinary tract distention and location and size of all lesions suspected of being urothelial tumors were recorded. Standard of reference was obtained from prospective study interpretation and surgical histopathologic findings. Generalized estimating equations for logistic regression were used to compare performance measures and adjust for the correlation of repeated measures within patients. RESULTS There were 23 upper and 61 lower urinary tract tumors confirmed in 15 and 32 patients, respectively. For detection of bladder tumors, there was higher sensitivity for the UP than the EP (89.3% [109 of 122] vs 70.5% [86 of 122], respectively; P<.0001). For detection of upper tract tumors, there was higher sensitivity for the UP than the EP (82.6% [38 of 46] vs 69.6% [32 of 46], respectively; P=.0194). Distention of all upper urinary tract segments was better during the EP than the UP (P<.0001). CONCLUSION UP CT urography after injection of a diuretic has a higher lesion detection rate than the EP for both upper and lower urinary tract tumors, which suggests its possible use as a single-phase protocol for evaluation of the entire urinary tract in patients at high risk for urothelial tumors.

No Role for Routine Chest Radiography in Stage I Seminoma Surveillance

BACKGROUND After orchidectomy, the standard management options available for stage I seminoma are surveillance, adjuvant radiotherapy, or adjuvant chemotherapy. The optimal follow-up protocol for surveillance is yet to be determined but includes frequent chest radiography (CXR) and computed tomography (CT) scan of the abdomen and pelvis (CT-AP). OBJECTIVE The purpose of this study was to identify the modality that first detected relapse and to assess the value of the CXR in this setting. DESIGN, SETTING, AND PARTICIPANTS Five hundred twenty-seven patients with histologically confirmed stage I testicular seminoma were managed with surveillance at our institution between 1982 and 2005. Routine CXRs were performed with each CT-AP and were done every 4-6 mo for 7 yr and annually thereafter. The median follow-up was 72 mo (range: 1-193). MEASUREMENTS Measurements included the 5-yr relapse rate, overall survival, and disease-free survival to determine the modality that first detected relapse disease. RESULTS AND LIMITATIONS The 5-yr actuarial relapse rate for the 527 patients was 14%. The 5-yr disease-free survival and overall survival were 85.7% and 98.6%, respectively. Seventy-three patients (97.3%) had an abnormal CT-AP and a normal CXR at relapse. One patient (1.3%) had an abnormal CT-AP with pulmonary metastasis on CXR and CT chest scan, and one patient (1.3%) had a biopsy-proven inguinal node metastasis with a normal CXR. No patient had a normal CT-AP or physical examination with an abnormal CXR at relapse. This is a single-center retrospective study based on a relatively small number of relapses and may be subject to bias. Confirmation of these results from other studies would be useful for wider clinical applicability. CONCLUSIONS All except one relapse were detected by CT-AP with no relapses detected on CXR alone; therefore, CXR may be omitted as routine imaging in surveillance protocols.

Small Renal Oncocytomas: Is Segmental Enhancement Inversion a Characteristic Finding at Biphasic MDCT?

OBJECTIVE The purpose of this study was to retrospectively determine whether segmental enhancement inversion was a common and characteristic finding in small (≤ 4 cm) renal oncocytomas on biphasic contrast-enhanced CT. MATERIALS AND METHODS This retrospective case-control study included 16 patients with 16 renal oncocytomas and 15 control patients with 15 renal cell carcinomas (RCCs), matched for age and sex, who underwent biphasic contrast-enhanced MDCT at our institution. Three reviewers independently analyzed each tumor for enhancement patterns on MDCT, including the presence or absence of segmental enhancement inversion, homogeneity, and phase of peak enhancement. RESULTS The mean and median sizes of the oncocytomas were 2.5 and 2.4 cm, respectively (range, 1.1-3.9 cm), and the mean and median sizes of the RCCs were both 2.6 cm (range, 1.4-3.9 cm). There was no significant difference in the size of the renal masses between the two groups (p = 0.50). For two reviewers, segmental enhancement inversion was not present in any of the renal masses; for one reviewer, segmental enhancement inversion was present in one oncocytoma (6%) and one RCC (7%). For all reviewers, there was no feature or enhancement pattern that was statistically significantly associated with renal oncocytoma or RCC (p < 0.05). CONCLUSION Segmental enhancement inversion was not a common or characteristic CT finding for renal oncocytoma and was not helpful in differentiating small renal oncocytomas from RCC.

Mapping patterns of nodal metastases in seminoma: rethinking radiotherapy fields.

BACKGROUND AND PURPOSE To analyze the location of metastatic lymph nodes in seminoma patients relative to vascular and bony anatomy and conventional radiation fields. MATERIALS AND METHODS Cross-sectional scans of 90 seminoma patients with infradiaphragmatic adenopathy were analyzed. The position of each node respective to vascular anatomy was transferred to a standardized template. Conventional radiation fields were overlaid on the template and locations of metastatic nodes were assessed. RESULTS One hundred and forty-five nodes were radiographically positive. Eighty-four percent, 9%, and 7% of nodes were located in the para-aortic, common iliac, and pelvic regions, respectively. Ninety-nine percent of nodes were within a 2.5 cm lateral and 2.1cm anterior expansion of the aorta inferior to T12/L1. No radiographically positive nodes were identified within the renal hilum or superior to L1 in left-sided seminomas. For right-sided seminomas, no radiographically positive nodes were superior to L2. Three percent of all radiographically positive nodes would have been located outside of conventional and modified fields. CONCLUSIONS Infradiaphragmatic nodal metastases from a contemporary cohort of seminoma patients localized to a smaller area than is targeted by conventional radiation fields. Modified treatment fields based on vascular, rather than bony, anatomy are smaller and may allow for a significant decrease in normal tissue irradiation and toxicity.

Canadian Association of Radiologists Radiation Protection Working Group: Review of Radiation Units and the Use of Computed Tomography Dose Indicators in Canada

Radiation has played a vital role in health care for overa century now. Since Roentgen’s first radiograph in 1895, themedical imaging community has made tremendous advanceswith imaging technology, leading to earlier detectionof disease, minimally invasive approaches to diagnosisand therapy, and, most importantly, improved patientoutcome.Ionizing radiation can directly damage tissue and isrecognized by multiple national and international bodies asa weak carcinogen [1e3]. Direct tissue damage is referred toas the deterministic effect of radiation and will occur afterthe patient receives a radiation dose that exceeds a threshold,whereas the risk of cancer is referred to as a random orstochastic effect, with the probability of developing cancerincreasing with increasing radiation dose to the patient. Bothdeterministic and stochastic effects are a function ofradiation dose, a concept with multiple terminologies thathas led to significant confusion in practice. With an increasedreliance on medical imaging for patient care, both the short-and long-term risks associated with each imaging proceduremust be understood by all practitioners. The CanadianAssociation of Radiologists (CAR) has formed the RadiationProtection Working Group (RPWG) to provide leadership ondose education in Canada. This group aims to developstandards on diagnostic medical radiation protection todecrease patient risk and provide the CAR membership withinformation, online dose-calculating tools, and a forum todiscuss medical radiation dose in Canada.In this first essay, 3 important concepts will be discussed:radiation risk models, radiation units and the dose deliveredby medical imaging systems, and the estimated radiationdose received by the patient. Because computed tomographic(CT) examinations account for the majority of total radiationreceived by patients, especially when considering thedisproportionately lower examination frequency comparedwith other medical imaging examinations [4,5], theseconcepts will be discussed with a specific emphasize on dosefrom common CT examinations.

Lymph Node Growth Rate in Testicular Germ Cell Tumours: Implications for Computed Tomography Surveillance Frequency

AIM To estimate the growth rate of lymph nodes in patients on surveillance for testicular cancer who developed recurrent disease. MATERIALS AND METHODS During a 7-year period, 318 patients at our institution were managed by surveillance and 39 relapsed (12.3%). The computed tomography scans of 28 patients (median age 32 years; range 19-51 years) who met our inclusion criteria and who developed recurrent disease in the abdomen/pelvis were retrospectively reviewed. Thirteen patients had non-seminoma and 15 had seminoma. To estimate the lymph node growth rate, the slope of lymph node size over time was calculated. RESULTS The median length of time from orchiectomy to the recurrence computed tomography was 131 days (range 49-520) or about 4.4 months for non-seminoma patients and 373 days (range 129-675) or about 12.3 months for seminoma patients. The median size of the involved lymph node at final computed tomography for seminoma patients was 12 mm (range 9-31 mm) and for non-seminoma patients was 15 mm (range 10-56 mm). The median lymph node growth rate for patients with seminoma was 1.35 mm/month (range 0.62-4.56) and for patients with non-seminoma 2.99 mm/month (range 0.77-7.06); the difference in growth rates was statistically significant (P=0.029). CONCLUSIONS There is a statistically significant faster growth rate of lymph nodes in patients with recurrent non-seminoma compared with patients with seminoma. This finding supports a more frequent computed tomography schedule during the first 2 years of surveillance in non-seminoma patients compared with seminoma patients.

Canadian Association of Radiologists Radiation Protection Working Group: Automated Patient-Specific Dose Registries—What Are They and What Are They Good for?

Medical radiation should be used appropriately and with a dose as low as reasonably achievable. Dose monitoring technologies have been developed that automatically accumulate patient dose indicators, providing effective dose estimates and patient-specific dose histories. Deleterious radiation related events have prompted increased public interest in the safe use of medical radiation. Some view individualized patient dose histories as a tool to help manage the patient dose. However, it is imperative that dose monitoring technologies be evaluated on the outcomes of dose reduction and effective patient management. Patient dose management needs to be consistent with the widely accepted linear no-threshold model of stochastic radiation effects. This essay reviews the attributes and limitations of dose monitoring technologies to provoke discussion regarding resource allocation in the current fiscally constrained health care system.