Acute ureteric calculus obstruction: unenhanced spiral CT versus HASTE MR urography and abdominal radiograph

ACR Appropriateness Criteria® Acute Onset Flank Pain-Suspicion of Stone Disease (Urolithiasis)

Noncontrast CT (NCCT) is the imaging study of choice for initial evaluation of patients with acute onset of flank pain and suspicion of stone disease without known prior stone disease. NCCT can reliably characterize the location and size of an offending ureteral calculus, identify complications, and diagnose alternative etiologies of abdominal pain. Although less sensitive in the detection of stones, ultrasound may have a role in evaluating for signs of obstruction. Radiography potentially has a role, although has been shown to be less sensitive than NCCT. For patients with known disease and recurrent symptoms of urolithiasis, NCCT remains the test of choice for evaluation. In pregnancy, given radiation concerns, ultrasound is recommended as the initial modality of choice with potential role for noncontrast MRI. In scenarios where stone disease suspected and initial NCCT is inconclusive, contrast-enhanced imaging, either with MRI or CT/CT urogram may be appropriate. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Shockwave Lithotripsy for De-Novo Urolithiasis after Kidney Transplantation: A Systematic Review of the Literature

BACKGROUND

Allograft urolithiasis is an uncommon, challenging, and potentially dangerous clinical problem. Treatment of allograft stones includes external shockwave lithotripsy (SWL), flexible ureteroscopy and lasertripsy (fURSL), or percutaneous nephrolithotomy (PCNL). A gap in the literature and guidelines exists regarding the treatment of patients in this setting. The aim of this systematic review was to collect preoperative and treatment characteristics and evaluate the outcomes of post-transplant SWL for stone disease.

METHODS

A systematic search in the literature was performed, including articles up to March 2023. Only original English articles were selected.

RESULTS

Eight articles (81 patients) were included in the review. Patients were mainly male, with a mean age of 41.9 years (±7.07). The mean stone size was 13.18 mm (±2.28 mm). Stones were predominantly located in the kidney (n = 18, 62%). The overall stone-free rate and complication rates were 81% (range: 50-100%) and 17.2% (14/81), respectively, with only one major complication reported. A pre-operative drainage was placed in eleven (13.5%) patients. Five patients (6.71%) required a second treatment for residual fragments.

CONCLUSIONS

SWL is a safe and effective option to treat de novo stones after transplantation. Larger studies are needed to better address allograft urolithiasis management.

The Role of Radiological Imaging in the Diagnosis and Treatment of Urolithiasis: A Narrative Review

The incidence and prevalence of urolithiasis have been increasing worldwide for the last several decades. This increase could be attributed to many factors, including missed cases of small stones, a sedentary lifestyle, a high BMI, a lack of physical activity, and poor dietary intake. In addition, the increased incidence of co-morbidities such as diabetes, dyslipidemia, infections, and multiple urinary tract surgeries could contribute significantly to the formation of urolithiasis. Radiology has a major role in diagnosing a variety of these stone types and can be used in planning management approaches, either as guidance or as a direct therapeutic method for stones. Because of the availability, safety, cost, and effectiveness of radiological imaging nowadays, urolithiasis is rarely missed; furthermore, the availability of radiological treatment options decreases the need for surgical intervention for urolithiasis, which minimizes hospital stay and surgical-related complications. This review aims to scope and analyze the role of radiological imaging modalities in reaching a diagnosis and planning treatment options for urolithiasis in different circumstances. Information was gathered from relevant peer-reviewed publications in PubMed and thereafter refined and summarized to provide a comprehensive review. The selected indexing terms included "radiological imaging modality," "treatment of urolithiasis," and "diagnosis of urolithiasis," among others.

Management of ureteric stone in pregnancy: a review

Background

Urolithiasis in pregnancy is a major health concern and is one of the most common causes for non-obstetrical abdominal pain and subsequent hospital admission during pregnancy. The incidence of urinary calculi during pregnancy varies in the range of 1/200 to 1/2000. Acute ureteric colic in pregnancy is associated with significant potential risks to both mother and fetus. Significant anatomic and functional changes occur in pregnancy which not only lead to stone formation but also create diagnostic dilemma. The diagnosis of ureteric calculi can be incorrect in about 28% of pregnant patients.

Main body

Management of ureteric stone during pregnancy is remaining to be a challenge for the treating urologist. Because of the inability to use good imaging options for the diagnosis confirmation and more invasive approach for the treatment, management continues to be difficult. The main threats are preterm labor with delivery and premature rupture of membranes. Other pregnancy complications are obstructive uropathy, gestational diabetes mellitus, recurrent abortions and pre-eclampsia. Management of diagnosed ureteric stone is unique in the pregnant population and requires multi-disciplinary care. It should be individualized for each patient and moves preferably from conservative to invasive approaches sequentially. With continued advancements in endourological techniques, few definitive treatment options are also available for such patients.

Conclusion

There are several lacunae related with the diagnostic imaging, medical expulsive therapy, reliability of ureteral stent/percutaneous nephrostomy insertions and safety of ureteroscopy during pregnancy. Herein, we review the management of ureteric stone during pregnancy, the various diagnostic modalities and treatment options with their advantages and disadvantages. We also proposed our management algorithm to deal with such clinical scenario in this particular population.

ACR Appropriateness Criteria® Recurrent Lower Urinary Tract Infections in Females

Urinary tract infections (UTIs) in women are common, with an overall lifetime risk over >50%. UTIs are considered recurrent when they follow complete clinical resolution of a previous UTI and are usually defined as at least three episodes of infection within the preceding 12 months. An uncomplicated UTI is classified as a UTI without structural or functional abnormalities of the urinary tract and without relevant comorbidities. Complicated UTIs are those occurring in patients with underlying structural or medical problems. In women with recurrent uncomplicated UTIs, cystoscopy and imaging are not routinely used. In women suspected of having a recurrent complicated UTI, cystoscopy and imaging should be considered. CT urography or MR urography are usually appropriate for the evaluation of recurrent complicated lower urinary tract infections or for women who are nonresponders to conventional therapy, develop frequent reinfections or relapses, or have known underlying risk factors. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

"Renal emergencies: a comprehensive pictorial review with MR imaging"

Superior soft-tissue contrast and high sensitivity of magnetic resonance imaging (MRI) for detecting and characterizing disease may provide an expanded role in acute abdominal and pelvic imaging. Although MRI has traditionally not been exploited in acute care settings, commonly used in biliary obstruction and during pregnancy, there are several conditions in which MRI can go above and beyond other modalities in diagnosis, characterization, and providing functional and prognostic information. In this manuscript, we highlight how MRI can help in further assessment and characterization of acute renal emergencies. Currently, renal emergencies are predominantly evaluated with ultrasound (US) or computed tomography (CT) scanning. US may be limited by various patient factors and technologist experience while CT imaging with intravenous contrast administration can further compromise renal function. With the advent of rapid, robust non-contrast MRI, and magnetic resonance angiography (MRA) imaging studies with short scan times, free-breathing techniques, and lack of ionization radiation, the utility of MRI for renal evaluation might be superior to CT not only in diagnosing an emergent renal process but also by providing functional and prognostic information. This review outlines the clinical manifestations and the key imaging findings for acute renal processes including acute renal infarction, hemorrhage, and renal obstruction, among other entities, to highlight the added value of MRI in evaluating the finer nuances in acute renal emergencies.

The diagnostic value of magnetic resonance urography for detecting ureteric obstruction: a systematic review and meta-analysis

OBJECTIVE

To evaluate the diagnostic accuracy of magnetic resonance urography (MRU) and determine its value for detecting ureteric obstruction.

METHODS

The electronic databases, including PubMed, Embase and the Cochrane library, were systematically searched for studies published throughout September 2018. The summary of sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and receiver operating characteristic (ROC) curves was assessed to evaluate the diagnostic accuracy of MRU. Subgroup analyses were conducted based on the mean age of the included patients (adults or children).

RESULTS

Eight studies with a total of 594 patients were included. The summary of the sensitivity and specificity of MRU for diagnosing ureteric obstruction was 0.94 and 0.87, respectively. Furthermore, the pooled PLR and NLR were 7.33 and 0.07, respectively. The DOR of MRU for detecting ureteric obstruction was 95.12. In addition, the summary of the area under the ROC of MRU was 0.96. Finally, the specificity, PLR and area under the ROC of MRU for diagnosing ureteric obstruction in adults were higher than children, while the sensitivity of MRU in adults was lower than children.

CONCLUSIONS

These findings suggested a relatively high diagnostic value of MRU for detecting ureteric obstruction. Moreover, the diagnostic accuracy of MRU in adults was higher than in children. KEY MESSAGE Magnetic resonance urography (MRU) in detecting ureteric obstruction has relatively better sensitivity, specificity, PLR, NLR, DOR and AUC. The diagnostic value, including specificity, PLR and AUC of MRU in adults, was higher than in children, while the sensitivity of MRU in adults was lower than in children.

Assessment of ureteric diameter using contrast-enhanced helical abdominal computed tomography

Background

Assessment of ureteric size is imperative for diagnosis of urinary tract abnormalities especially with regard to obstructive pathologies. The ureteric opacification and distension obtained from contrast-enhanced computed tomography allows for differentiation from surrounding soft tissue and better assessment of ureteric diameter. Abdominal computed tomographic scans are commonly requested for the evaluation of the urinary tract, and we therefore aim to establish a normal reference value of the ureteral diameter using contrast-enhanced computed tomographic scans of the abdomen.

Method

With the purpose of establishing our local normogram of ureteric diameter, we did a retrospective study of archived images of 170 patients referred to the radiology department of a tertiary hospital for contrast-enhanced abdominal CT from January 2016 to June 2018. The largest transverse dimension along the course of the ureter beginning 1–2 cm below the ureteropelvic junction was measured at the delayed phase and obtained data subjected to analysis using SAS software version 9.3 with statistical level of significance set at 0.05.

Result

A total number of 340 ureters in 170 patients were analyzed with the mean age of 47.9 years (range 1.0–94.0 years) and male-to-female ratio of 1.2:1. The mean left ureteric diameter of all patients was 4.3 mm (range 1.7–8.0 mm) while the mean right ureteric diameter of all patients was 4.4 mm (range 1.5–8.0 mm). Ninety-five percent of ureters in our study measured 6.9 mm and less with no significant difference in ureteric sizes across gender and ages.

Conclusion

The mean CT normogram for ureteric caliber is 4.3–4.4 mm with no significant age and gender difference and 7 mm proposed as upper limit of normal.

Contemporary best practice urolithiasis in pregnancy

Urolithiasis is the most common nonobstetric complication in the gravid patient. The experience can provoke undue stress for the mother, fetus, and management team. The physiologic changes of pregnancy render the physical exam and imaging studies less reliable than in the typical patient. Diagnosis is further complicated by the need for careful selection of imaging modality in order to maximize diagnostic utility and minimize obstetric risk to the mother and ionizing radiation exposure to the fetus. Ultrasound remains the first-line diagnostic imaging modality in this group, but other options are available if results are inconclusive. A trial of conservative management is uniformly recommended. In patients who fail spontaneous stone passage, treatment may be temporizing or definitive. While temporizing treatments have classically been deemed the gold standard, ureteroscopic stone removal is now acknowledged as a safe and highly effective definitive treatment approach. Ultimately, a multidisciplinary, team-based approach involving the patient, her obstetrician, urologist, radiologist, and anesthesiologist is needed to devise a maximally beneficial management plan.

Urolithiasis in pregnancy

Urolithiasis in pregnancy is a major health concern and can potentially affect the well-being of both mother and foetus. Management of this condition often entails simultaneous multidisciplinary involvement of obstetrician, radiologist and urologist. Additionally, adverse effects with usage of anaesthesia, radiation, medications and surgery on mother and foetus, limit utilisation of the full armamentarium of diagnostic and therapeutic modalities that are commonly used in non-pregnant women. This review was conducted using an electronic literature search of peer reviewed journal articles. Clinical studies were identified in the bibliographic database- PubMed (Medline), Ovid and eMedicine(WebMD) using the keywords: hydronephrosis, urolithiasis, kidney stone, urinary tract infection, pregnancy and ultrasound, incidence and epidemiology of renal stones.

Imaging of flank pain: readdressing state-of-the-art

Pain resulting from renal and ureteral stones is a common cause for patients presenting in the acute setting. Since the late 1990s, computed tomography (CT) has been the initial imaging method of choice to evaluate patients with suspected ureteral stones; however, concerns regarding both radiation dose and cost-effectiveness have prompted investigations into a different imaging algorithm. Studies utilizing ultrasound have provided evidence indicating that it may be a more appropriate first step, with selective use of CT in selected cases, in the diagnostic work-up. Techniques have evolved with low-dose CT, dual-energy CT, and magnetic resonance urography emerging as useful in imaging of renal colic patients. This manuscript reviews the current literature on state-of-the-art imaging for acute flank pain and proposes a new imaging algorithm in the evaluation of patients with acute flank pain and suspected ureteral stones.

The diagnostic value of magnetic resonance urography using a balanced turbo field echo sequence

OBJECTIVES

The aim of the study was to compare the inter-observer variability and the accuracy of magnetic resonance urography (MRU) using a thin sectional balanced-turbo field echo (B-TFE) sequence for detecting ureteral calculi and to determine the effect of additional factors (size, density and location of the calculus) on the sensitivity and specificity of the MRU.

MATERIALS & METHODS

MRU and CT images were evaluated independently by two radiologists according to presence, density and localization of calculi. The degrees of inter-rater agreement for categorical items were evaluated by the Kappa coefficient.

RESULTS

According to the 1st and 2nd observers, the sensitivity of MRU was 65.9 %, 71.8 % and the specificity of MRU was 95.9 %, 100 %, respectively. Inter-observer agreement was 84.6 % for stone detection. The larger size had a better effect on detectability (p < 0.05). Also, the higher density had a better impact on detectability (p < 0.05).

CONCLUSION

Our study has shown that B-TFE MRU was useful to detect ureteral calculi. However, B-TFE MRU has low sensitivity and high specificity in comparison with CT images. MRU is a reasonable alternative imaging technique for follow-up periods of selective groups like patients with large urinary stones, children or pregnant patients when ionizing radiation is undesirable.

KEY POINTS

• According to 1st and 2nd observers, sensitivity of MRU was 65.9 %, 71.8 %, respectively. • According to 1st and 2nd observers, MRU specificity was 95.9 %, 100 %, respectively. • Interobserver agreement was found to be over 84 % for stone detection. • B-TFE sequence provides calculus follow-up without radiation. • Larger calculi and more dense calculi individually have the better effect on detectability.

Magnetic Resonance Imaging of Abdominal and Pelvic Pain in the Pregnant Patient

The utility of MR imaging in evaluating abdominal and pelvic pain in the pregnant patient is discussed. Details regarding the indications, technical aspects, and imaging findings of various common abdominal and pelvic abnormalities in pregnancy are reviewed.

Evaluation of microscopic hematuria: a critical review and proposed algorithm

Microscopic hematuria (MH), often discovered incidentally, has many causes, including benign processes, kidney disease, and genitourinary malignancy. The clinician, therefore, must decide how intensively to investigate the source of MH and select which tests to order and referrals to make, aiming not to overlook serious conditions while simultaneously avoiding unnecessary tests. Existing professional guidelines for the evaluation of MH are largely based on expert opinion and have weak evidence bases. Existing data demonstrate associations between isolated MH and various diseases in certain populations, and these associations serve as the basis for our proposed approach to the evaluation of MH. Various areas of ongoing uncertainty regarding the appropriate evaluation should be the basis for ongoing research.

Stone disease in pregnancy: imaging-guided therapy

Renal colic is the most frequent nonobstetric cause for abdominal pain and subsequent hospitalization during pregnancy. The physio-anatomical changes in the urinary tract and the presence of the fetus may complicate the clinical presentation and management of nephrolithiasis. Ultrasound (US) is the primary radiological investigation of choice. Magnetic resonance urography (MRU) and low-dose computed tomography (CT) have to be considered as a second- and third-line test, respectively. If a study that uses ionizing radiation has to be performed, the radiation dose to the fetus should be as low as possible. The initial management of symptomatic ureteric stones is conservative during pregnancy. Intervention will be necessary in patients who do not respond to conservative measures. Therefore, it is crucial to obtain a prompt and accurate diagnosis to optimize the management of these patients. Teaching Points • In pregnancy, renal colic is the most frequent nonobstetric cause for abdominal pain and hospitalization. • Magnetic resonance urography should be considered when ultrasound is nondiagnostic. • Low-dose CT should be considered as a last-line test during pregnancy.

Diagnosis and staging of bladder cancer

Bladder cancer (BCa) is a heterogeneous disease with a variable natural history. Most patients (70%) present with superficial tumors (stages Ta, T1, or carcinoma in situ). However, 3 out of 10 patients present with muscle-invasive disease (T2-4) with a high risk of death from distant metastases. Moreover, roughly between 50% and 70% of superficial tumors do recur, and approximately 10% to 20% of them progress to muscle-invasive disease. However, BCa has a relatively low ratio of mortality versus incidence of new cases. In consequence, there is the danger of overdiagnosis and overtreatment.

MR imaging for acute nontraumatic abdominopelvic pain: rationale and practical considerations

Medical imaging is becoming an increasingly vital component of patient care in the emergency department. Computed tomography has been the diagnostic imaging method of choice for emergency department patients with acute abdominopelvic pain; however, the use of ionizing radiation and the potential need for exogenous contrast material adversely affect patient safety and work flow efficiency, respectively. Magnetic resonance (MR) imaging holds promise as an alternative for the evaluation of acute abdominopelvic pain. Critical causes of abdominopelvic pain may be detected with MR imaging without exogenous contrast material. MR imaging is sensitive for depicting tissue or fluid changes related to inflammation, a common process in causes of acute abdominopelvic pain. Fat suppression allows the detection of abnormal signal caused by inflamed tissue. MR imaging has proved sensitive in the detection of acute inflammatory diseases of the gallbladder and bile ducts, liver, pancreas, kidneys, collecting system, bowel, and pelvic soft tissues. Moreover, MR imaging without exogenous contrast material may be safely used in pregnant patients. Evolving roles for emergency department MR imaging include the assessment of vascular disease (including thromboembolic disease) and right upper quadrant pain. Emergency department MR imaging currently has limited availability, and its continued use will require further education regarding operation and image interpretation as well as further validation of cost-effectiveness. Nevertheless, current understanding of the diagnostic utility of this imaging method warrants continued study and the increased use of MR imaging in the evaluation of emergency department patients with acute abdominopelvic pain.

[Radiology and pregnancy : Part 2: clinical recommendations]

In spite of a growing number of radiological scans in pregnant women there is still a high level of uncertainty concerning radiation exposure to the fetus. At the same time, the risk of fetal radiation injury is frequently overestimated. This entails an avoidable fear in the pregnant patient and may delay urgently required imaging and thus lead to an increased risk for maternal and fetal health. As a consequence, radiological scans in pregnant patients do not only require a thorough medical check but also a careful estimate of the specific radiation exposure to the fetus. The previous first part of the article described the legal requirements in Germany, the technical exposure and pharmacological risks for the pregnant woman and the fetus. The current second article focuses on the risk analysis for examinations with ionizing radiation and will provide recommendations for typical indications for maternal and fetal imaging.

Contrast-enhanced magnetic resonance urography at 3T: clinical feasibility

OBJECTIVE

The objective of this study was to assess the feasibility of performing diagnostic-quality contrast-enhanced excretory magnetic resonance urography (eMRU) at 3T, examining both image quality and diagnostic accuracy for a range of urinary tract abnormalities.

METHODS

The diuretic-enhanced 3T eMRUs of 37 patients were reviewed to assess for the diagnostic conspicuity of urinary tract abnormalities, extent of urinary tract visualization on excretory images, and presence and severity of image artifacts.

RESULTS

Excretory images allowed greater than 75% visualization in 90.8% of renal collecting systems, 90.8% of ureters, and 82.3% of bladders. Common artifacts included susceptibility (21.3%), contrast mixing (21.3%), patient motion (20.4%), signal inhomogeneity (19.4%), and peristaltic motion (17.6%). Severe artifacts occurred in 21.6% of studies. Five of 8 urothelial neoplasms were detected, with 1 false-positive lesion in the bladder. Urolithiasis was correctly diagnosed in 7 of 9 patients.

CONCLUSIONS

Although image artifacts can hamper eMRU at 3T, initial results are promising for evaluation of the urothelium.

The role of static magnetic resonance urography in the evaluation of obstructive uropathy

OBJECTIVE

To assess the diagnostic accuracy of static magnetic resonance urography (MRU) in hydronephrosis and to compare parameters of hydronephrosis in MRU with intravenous urography (IVU).

MATERIALS AND METHODS

Sixty-nine patients were included in this study of which 55 patients with a total of 63 hydronephrotic units underwent both IVU and MRU. MRU was performed on a 1.5 T scanner using heavily T2-weighted sequences. The level, grade, and cause of obstruction on each modality were interpreted by 2 radiologists. These were compared with the final diagnosis based on other appropriate modalities including imaging, intraoperative and histopathologic diagnosis.

RESULTS

The sensitivity and specificity MRU in detecting hydronephrosis were 95% and 100%, respectively. In determining the level of obstruction, the strength of agreement between IVU and MRU using kappa statistics was κ = 0.66, which corresponds to a good level of agreement. The Spearman correlation coefficient for the grade of hydronephrosis on MRU and IVU was 0.92 (95% confidence interval 0.86-0.95), with a P value of < .0001. The correct diagnosis was made in 89.2% of the cases by IVU and in 93.8% of the cases by MRU.

CONCLUSION

Along with a high sensitivity and specificity in detecting the presence, level, and grade of hydronephrosis, MRU without contrast also shows a good agreement with IVU. Static MRU can reliably replace IVU when the latter is contraindicated or technically difficult.

Imaging techniques for stone disease and methods for reducing radiation exposure

Imaging plays a critical role in the evaluation of patients with urolithiasis. It is essential for the diagnosis of stones and provides important information to aide in determining the appropriate treatment of renal or ureteral calculi. Imaging for urolithiasis has evolved over the past 30 years. Currently, noncontrast computed tomography remains the first-line imaging modality for the evaluation of patients with suspected urolithiasis. Proper imaging modality selection helps to minimize radiation exposure. Following the principles of As Low As Reasonably Achievable in the operating room can help reduce the amount of radiation patients are exposed to from fluoroscopy.

Comparison of secondary signs as shown by unenhanced helical computed tomography in patients with uric acid or calcium ureteral stones

Unenhanced helical computed tomography (UHCT) has evolved into a well-accepted diagnostic method in patients with suspected ureterolithiasis. UHCT not only shows stones within the lumen of the ureter, it also permits evaluation of the secondary signs associated with ureteral obstruction from stones. However, there we could find no data on how secondary signs might differ in relation to different compositions of ureteral stones. In this study, we compared the degree of secondary signs revealed by UHCT in uric acid stone formers and in patients forming calcium stones. We enrolled 117 patients with ureteral stones who underwent UHCT examination and Fourier transform infra-red analysis of stone samples. Clinical data were collected as follows: age, sex, estimated glomerular filtration rate (eGFR), urine pH, and radiological data on secondary signs apparent on UHCT. The uric acid stone formers had significantly lower urine pH and eGFR in comparison to calcium stone formers, and on UHCT they also had a higher percentage of the secondary signs, including rim sign (78.9% vs. 60.2%), hydroureter (94.7% vs. 89.8%), perirenal stranding (84.2% vs. 59.2%) and kidney density difference (73.7% vs. 50.0%). The radiological difference was statistically significant for perirenal stranding (p=0.041). In conclusion, we found that UHCT scanning reveals secondary signs to be more frequent in patients with uric acid ureteral stones than in patients with calcium stones, a tendency that might result from an acidic urine environment.

Imaging of pregnant and lactating patients: part 2, evidence-based review and recommendations

OBJECTIVE

The objectives of this article are to discuss the current evidence-based recommendations regarding the use of diagnostic imaging in the evaluation of pulmonary embolism, appendicitis, urolithiasis, and cholelithiasis during pregnancy.

CONCLUSION

Diagnostic imaging should be performed during pregnancy only with an understanding of the maternal and fetal risks and benefits, the comparative advantages of different modalities, and the unique anatomic and physiologic issues associated with pregnancy.

Half Fourier single-shot turbo spin-echo magnetic resonance urography for the evaluation of suspected renal colic in pregnancy

OBJECTIVE

To report our experience with magnetic resonance urography (MRU) in pregnant women suspected of having obstructing upper tract calculi. The diagnosis of an upper tract calculus in the pregnant woman can be challenging. Recent evidence suggests that MRU can be used to effectively evaluate renal colic.

METHODS

From 2008-2011, 9 pregnant women were referred for evaluation of suspected renal colic caused by an obstructing upper tract stone. All patients underwent MRU with a half Fourier single-shot turbo spin-echo (HASTE) protocol. Medical records and imaging studies were reviewed for demographic and clinical data as well as outcome measures.

RESULTS

The mean age of the subjects was 25 years (range 20-34); average gestational age of the fetus was 23 weeks (range 9-36). In all cases, a renal ultrasound was the initial imaging study obtained, with nondiagnostic findings. HASTE MRU detected 4 ureteral stones and 4 cases of physiological hydronephrosis of pregnancy. In one case, interpretation of the MRU was limited as a result of patient motion. Of the patients with obstructing stones, 1 required endourologic management during her pregnancy and 3 were followed conservatively. No adverse events related to MRU occurred.

CONCLUSION

HASTE MRU is an informative imaging study for pregnant women with suspected upper tract stone disease. Information gathered from this study augments that gained from alternative modalities, and aids in medical decision-making. The lack of ionizing radiation exposure, coupled with the capture of detailed anatomic imaging, makes HASTE MRU a particularly useful study in this setting.

Nephrolithiasis: what surgeons need to know

OBJECTIVE

In this article, we review the standard of care for imaging of nephrolithiasis as well as new technology and radiation concerns from the perspective of the urologic surgeon.

CONCLUSION

Nephrolithiasis is a common cause of morbidity with a lifetime prevalence of 5-10% worldwide. Increasingly, diagnostic evaluation and planning for medical or surgical intervention have become reliant on imaging.

Acute abdominal pain: is there a potential role for MRI in the setting of the emergency department in a patient with renal calculi?

Acute flank pain is a frequent clinical presentation encountered in emergency departments, and a work-up for obstructive urolithiasis in this setting is a common indication for computed tomography (CT). However, imaging alternatives to CT for the evaluation of renal colic are warranted in some clinical situations, such as younger patients, pregnancy, patients that have undergone multiple prior CT exams and also patients with vague clinical presentations. MRI, although relatively insensitive for the direct detection of urinary calculi, has the ability to detect the secondary effects of obstructive urolithiasis. Using rapid, single shot T2-weighted sequences without and with fat saturation provides an abdominopelvic MR examination that can detect the sequelae of clinically active stone disease, in addition to alternate inflammatory processes that may mimic the symptoms of renal colic. In addition, MR nephro-urography (MRNU) has the ability to provide quantitative analysis of renal function that has the potential to direct clinical management in the setting of obstructing calculi. This review describes the potential utility and limitations of MRI in the emergency setting for diagnosing causes of flank pain and renal colic, particularly in patients with unusual presentations or when an alternative to CT may be warranted.

[Fornix rupture caused by a ureteral stone during pregnancy: non-contrast-enhanced MR urography]

Fornix rupture during pregnancy is rare. To be able to initiate the optimal therapy it is important to distinguish the spontaneous fornix rupture from the rupture caused by an obstruction. We report on a patient in the 18th week of pregnancy with strong flank pain on the left side. By means of MR urography the diagnosis of a left fornix rupture due to an obstructive stone could be made. A double-J catheter was placed in the left ureter and the patient received oral antibiotics.

Imaging modalities for urolithiasis: impact on management

PURPOSE OF REVIEW

Urolithiasis is a common urological problem, often requiring efficient workup, accurate diagnosis, and treatment. The purpose of this review is to summarize the imaging modalities employed for the diagnosis of calculi and the caveats of different clinical situations.

RECENT FINDINGS

Noncontrast computed tomography has become the most universally used imaging tool for diagnosing urolithiasis, although ultrasound and magnetic resonance imaging maintain specific roles. Noncontrast computed tomography may provide prognostic information regarding the success of specific management strategies for urolithiasis. Additionally, noncontrast computed tomography is being tested in lower-radiation dose protocols with promising results.

SUMMARY

Considering the well supported accuracy and relative ease of use of noncontrast computed tomography, it has become a logical choice for the urologist to use the technique as a diagnostic tool for stone disease. The future of imaging for intervention and surveillance of stone disease lies in the continued progress of noncontrast computed tomography in terms of patient safety. This will need to be done by developing low-dose radiation computed tomography that can replicate the efficacy of current noncontrast computed tomography.

MRI of the kidney-state of the art

Ultrasound and computed tomography (CT) are modalities of first choice in renal imaging. Until now, magnetic resonance imaging (MRI) has mainly been used as a problem-solving technique. MRI has the advantage of superior soft-tissue contrast, which provides a powerful tool in the detection and characterization of renal lesions. The MRI features of common and less common renal lesions are discussed as well as the evaluation of the spread of malignant lesions and preoperative assessment. MR urography technique and applications are discussed as well as the role of MRI in the evaluation of potential kidney donors. Furthermore the advances in functional MRI of the kidney are highlighted.

(Paediatric) magnetic resonance urography: just fancy images or a new important diagnostic tool?

PURPOSE OF REVIEW

Magnetic resonance urography has become an established imaging tool in uroradiology. Its potential to assess anatomy and function makes it an ideal tool for evaluation of urinary tract malformations, renal cysts, genito-urinary tract tumours, infections and renal transplants. This review tries to highlight the potential of magnetic resonance urography in the light of new advances, particularly focusing on paediatric applications.

RECENT FINDINGS

Technical innovations such as diaphragmatic tracking, parallel or propeller imaging, faster gradients and higher field strength improve applicability in infants and children. Dynamic studies enable assessment of renal functional parameters such as split renal function, glomerular filtration rate or urinary drainage. Recent advances in magnetic resonance spectroscopy, diffusion imaging and perfusion imaging and new contrast agents promise to widen the potential of magnetic resonance urography as a functional imaging tool, not only in paediatrics but also for other magnetic resonance applications in the genito-urinary tract, such as prostate imaging or in the staging of ovarian and endometrial cancer.

SUMMARY

Besides ultrasound being used as the initial imaging method, particularly in children (and as computed tomography in adults), magnetic resonance urography can be envisioned as the major imaging modality for almost all (paediatric) uroradiological queries, consequently creating a growing demand for available equipment and procedural expertise.

Diagnosis and management of renal (ureteric) colic

Renal (ureteric) colic is a common surgical emergency. It is usually caused by calculi obstructing the ureter, but about 15% of patients have other causes, e.g. extrinsic compression, intramural neoplasia or an anatomical abnormality. This review will focus on calculus-related renal or ureteric colic, its assessment and subsequent management.