Assessment of painful ureterohydronephrosis during pregnancy by MR urography

Imaging in stone diagnosis and surgical planning

PURPOSE OF REVIEW

Radiological imaging techniques and applications are constantly advancing. This review will examine modern imaging techniques in the diagnosis of urolithiasis and applications for surgical planning.

RECENT FINDINGS

The diagnosis of urolithiasis may be done via plain film X-ray, ultrasound (US), or contrast tomography (CT) scan. US should be applied in the workup of flank pain in emergency rooms and may reduce unnecessary radiation exposure. Low dose and ultra-low-dose CT remain the diagnostic standard for most populations but remain underutilized. Single and dual-energy CT provide three-dimensional imaging that can predict stone-specific parameters that help clinicians predict stone passage likelihood, identify ideal management techniques, and possibly reduce complications. Machine learning has been increasingly applied to 3-D imaging to support clinicians in these prognostications and treatment selection.

SUMMARY

The diagnosis and management of urolithiasis are increasingly personalized. Patient and stone characteristics will support clinicians in treatment decision, surgical planning, and counseling.

Kidney Imaging and Biopsy in Pregnancy

Physiologic glomerular, tubular, and structural changes related to pregnancy may complicate the detection of underlying kidney disease in pregnant patients. Imaging studies may provide important clinical information to assist in the diagnosis and treatment of kidney disease during pregnancy. Furthermore, in select patients who develop new or worsening kidney disease in pregnancy, kidney biopsy may be essential to ensure the accuracy of diagnosis and guide treatment choices. This review article will discuss the risks and benefits of various modalities used to image the kidneys and urinary tract during pregnancy to aid in the judicious selection of appropriate imaging studies that are likely to maximize clinical benefit while minimizing fetal risk. It will also highlight the potential benefits and harms associated with antepartum kidney biopsy and will offer strategies for identifying patients who are most likely to benefit from kidney biopsy during pregnancy.

Renal Colic Imaging: Myths, Recent Trends, and Controversies

There has been a substantial increase in the utilization of imaging, particularly of multi-detector computed tomography (MDCT), for the evaluation of patients with suspected urolithiasis over the past 2 decades. While the diagnostic accuracy of computed tomography (CT) for urolithiasis is excellent, it has also resulted in substantial medical expenditures and increased ionizing radiation exposure. This is especially concerning in patients with known nephrolithiasis and in younger patients. This pictorial review will focus on recent trends and controversies in imaging of patients with suspected urolithiasis, including the current roles of ultrasound (US), MDCT, and magnetic resonance imaging, the estimated radiation dose from MDCT and dose reduction strategies, as well as imaging of suspected renal colic in pregnant patients. The current epidemiological, clinical, and practice management literature will be appraised.

Water-enhanced antegrade MR pyelography in pregnancy: a novel radiation-free approach

Our aim was to determine if water-enhanced antegrade magnetic resonance (MR) pyelography can be an alternative to conventional antegrade pyelography in pregnant patients who require percutaneous nephrostomy placement for urosepsis and/or obstructive uropathy. The pregnant patient was placed supine in a 1.5-T MRI scanner seven days after percutaneous nephrostomy placement using ultrasound. Serial axial and coronal T2-weighted echo-planar fast spin-echo sequences were performed before and after injection of the catheter. The right nephrostomy catheter hub was sterilised using chlorhexidine. Sixty millilitres of sterile water were slowly injected. No Gd-based contrast agent was utilised due to safety concerns for the foetus. MR antegrade pyelography demonstrated the level of ureteric obstruction and the absence of renal calculi using sterile water as a contrast medium injected through a percutaneous nephrostomy followed by T2-weighted imaging. Air bubbles in the injected solution were differentiated from calculi due to their mobility on serial scans and their anti-dependent position. Water-enhanced antegrade MR pyelography was a safe and effective method of imaging the pregnant patient. It served as an alternative to conventional antegrade pyelography and minimised potential risks to the foetus.

Conservative/surgical treatment predictors of maternal hydronephrosis: results of a single-center retrospective non-randomized non-controlled observational study

PURPOSE

To determine the parameters that may help the clinicians decide the best suitable treatment method for the pregnant women with symptomatic hydronephrosis which will be based on the easily accessible laboratory tests, monitoring methods and clinical symptoms.

METHODS

Digital data and documents of 246 pregnant women with symptomatic hydronephrosis who were hospitalized in our clinic between the dates of January 2011 and January 2016 were retrospectively evaluated. All patients were statistically evaluated in terms of age, symptomatic maximal anterior-posterior diameter of the renal pelvis (MADP), parity, C-reactive protein (CRP) level, white blood cell count (WBC), presence of pyuria, growth of urine culture, fever, serum urine and creatinine levels, visual analog scale (VAS) score of pre- and post-therapy and threatened preterm labor.

RESULTS

The study includes a total of 211 pregnant women with symptomatic hydronephrosis. In the second and third trimester groups, the surgical treatment group statistically provided higher levels of CRP, WBC and VAS. Mean MADP in the second trimester of the conservative and surgical groups where symptomatic hydronephrosis was on the right side was 16.67 ± 4.67 and 28.68 ± 7.70 mm, respectively. Mean MADP in the third trimester group of the conservative and surgical groups where symptomatic hydronephrosis was on the right side was 16.96 ± 5.96 and 28.85 ± 7.64 mm, respectively.

CONCLUSIONS

In patients with symptomatic pregnancy hydronephrosis, the likelihood of surgical treatment for CRP levels, WBC counts and VAS is high.

Urolithiasis in pregnancy

Clinicians are faced with multiple diagnostic and treatment challenges when managing pregnant women with urolithiasis. Anatomical and physiological changes during pregnancy have to be taken into account whilst simultaneously considering both the expectant mother and the foetus. Ultrasonography remains the first-choice imaging modality, notwithstanding its potentially poor diagnostic accuracy. There is currently no consensus on second-line investigation for suspected urolithiasis. Low-dose non-contrast CT is highly sensitive, but the long-term effects of ionizing radiation on the foetus remain unknown. As far as treatment is concerned, expectant therapy is the primary option for management in the majority of cases. Percutaneous nephrostomy or ureteric stent placements are safe temporizing measures in relieving an acutely obstructed system and should be expedited in the presence of sepsis. Studies have shown ureteroscopy to be safe and effective during pregnancy with no significant risk to the foetus. It is important for the clinician to explain clearly the risks associated with the investigation and management options to the pregnant patient, including an acknowledgement that some of these remain unquantified, or even unknown.

The association between maternal hydronephrosis and acute flank pain during pregnancy: a prospective pilot-study

PURPOSE

Maternal hydronephrosis may cause flank pain during pregnancy. We aimed to investigate the association between maternal hydronephrosis and flank pain intensity.

METHODS

From 2014 to 2015, all consecutive women with singleton pregnancies, who presented at our tertiary center due to acute flank pain, were prospectively evaluated by renal ultrasonography and pain questionnaires. A visual analogue scale was used to assess pain intensity. The study had 90% power to detect a significant correlation between hydronephrosis and flank pain (Spearman's test).

RESULTS

A total of 51 consecutive women with left-sided (13.7%), right-sided (64.7%) or bilateral (21.6%) pain were enrolled. The mean gestational age of these women, who presented due to their pain, was 27.5 ± 6.8 weeks at the time of consultation. The mean VAS score was 7.6 ± 2.2. In 43/51 (84.3%) women, hydronephrosis was found on renal sonograms. No correlation was found between the grade of hydronephrosis and pain intensity (p = 0.466; r= -0.28). Women delivered at a mean gestational age of 38.1 ± 2.4 weeks and their infants had a mean birthweight of 3138 ± 677 g.

CONCLUSIONS

Hydronephrosis is a common finding among pregnant women with acute flank pain. The grade of hydronephrosis does not affect pain intensity. This study suggests normal pregnancy outcomes in these women.

Magnetic resonance imaging of acute abdominal and pelvic pain in pregnancy

Evaluation of acute abdominal and pelvic pain in pregnancy presents a diagnostic challenge for clinicians and radiologists alike. The differential diagnosis includes obstetric and nonobstetric conditions unique to pregnancy, in addition to causes of acute abdominal and pelvic pain unrelated to the pregnancy. The clinical presentation and course of disease may be altered in pregnancy, and several pathologies are exacerbated by pregnancy. Discriminating clinical features in the diagnosis of abdominal and pelvic pain are often confounded by expected anatomic and physiologic changes in pregnancy. Moreover, while diagnostic pathways may be altered in pregnancy, the necessity for a timely and accurate diagnosis must be underscored, as delay in treatment may result in an undesirable increase in morbidity and/or mortality for both the patient and fetus. Advances in magnetic resonance imaging (MRI) through faster acquisition and motion-insensitive techniques, coupled with increased awareness and education regarding the value of MRI in diagnosing a wide range of pathology, have established MRI as a valuable strategy in the investigation of acute abdominal and pelvic pain in the pregnant patient. This review presents a practical approach to common obstetric and nonobstetric causes of acute abdominal and pelvic pain during pregnancy, as well as safety considerations for performing MRI in this patient population.

Loss of renal India ink artifact-a useful radiological sign for obstructive hydronephrosis in pregnancy

Magnetic resonance imaging is a useful tool for investigating causes of abdominal pain in pregnancy. Differentiating between physiologic hydronephrosis of pregnancy and pathologic hydronephrosis can be challenging for clinicians and radiologists. This report describes loss of the India ink artifact around the obstructed kidney as a novel and potentially useful radiological sign, which may be of value in the evaluation of abdominal pain and hydronephrosis in pregnancy.

Kidney stones and pregnancy

Kidney stones are common and do not spare the pregnant population. Although a simple stone event is usually straightforward in the general population, it is complex during pregnancy. Acute nephrolithiasis is associated with a unique set of complications during pregnancy and, because of imaging limitations, diagnosis is challenging. Multidisciplinary care is the key in proper management decisions. The pathophysiology of kidney stone formation in the pregnant state is also unique. Herein, we discuss the complexity of kidney stones and pregnancy.

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.

ACR Appropriateness Criteria® Acute Pelvic Pain in the Reproductive Age Group

Premenopausal women who present with acute pelvic pain frequently pose a diagnostic dilemma, exhibiting nonspecific signs and symptoms, the most common being nausea, vomiting, and leukocytosis. Diagnostic considerations encompass multiple organ systems, including obstetric, gynecologic, urologic, gastrointestinal, and vascular etiologies. The selection of imaging modality is determined by the clinically suspected differential diagnosis. Thus, a careful evaluation of such a patient should be performed and diagnostic considerations narrowed before a modality is chosen. Transvaginal and transabdominal pelvic sonography is the modality of choice when an obstetric or gynecologic abnormality is suspected, and computed tomography is more useful when gastrointestinal or genitourinary pathology is more likely. Magnetic resonance imaging, when available in the acute setting, is favored over computed tomography for assessing pregnant patients for nongynecologic etiologies because of the lack of ionizing radiation. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every two years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Nontraumatic abdominal pain in pregnancy: imaging considerations for a multiorgan system problem

Nontraumatic abdominal pain in the pregnant patient can present a clinician with a variety of diagnostic possibilities. The overlap between signs and symptoms expected in normal pregnancy and these many pathologic possibilities does little to help focus the clinician's diagnostic efforts. Fear of ionizing radiation's effects on the fetus has driven efforts to refine medical imaging algorithms in such a way as to attempt to eliminate its use at all cost. In today's world, we are nearly there. In this review the differential diagnosis of nontraumatic abdominal pain in the pregnant patient will be explored. Of note is the recurring theme that much of what can be done today with regard to diagnostic imaging, both in general and with regard to this specific subset of patients, centers on the use of the non-ionizing modalities of ultrasound and magnetic resonance imaging.

Magnetic resonance urography

Excellent contrast resolution and lack of ionizing radiation make magnetic resonance urography (MRU) a promising technique for noninvasively evaluating the entire urinary tract. While MRU currently lags behind CT urography (CTU) in spatial resolution and efficiency, new hardware and sequence developments have contributed to a resurgence of interest in MRU techniques. By combining unenhanced sequences with multiphase contrast-enhanced and excretory phase imaging, a comprehensive assessment of the kidneys, ureters, bladder, and surrounding structures is possible with image quality rivaling that obtained with other techniques. At the same time, formidable challenges remain to be overcome and further clinical validation is necessary before MRU can replace other forms of urography. In this article, we demonstrate the current potential of MRU to demonstrate a spectrum of urologic pathology involving the kidneys, ureters, and bladder while discussing the limitations and current status of this evolving technique.

ACR Appropriateness Criteria on acute pelvic pain in the reproductive age group

Premenopausal women who present with acute pelvic pain frequently pose a diagnostic dilemma, exhibiting nonspecific signs and symptoms, the most common being nausea, vomiting, and leukocytosis. Diagnostic considerations encompass multiple organ systems, including obstetric, gynecologic, urologic, gastrointestinal, and vascular etiologies. The selection of imaging modality is determined by the clinically suspected differential diagnosis. Thus, a careful evaluation of such a patient should be performed and diagnostic considerations narrowed before a modality is chosen. Transvaginal and transabdominal pelvic sonography is the modality of choice when an obstetric or gynecologic abnormality is suspected, and computed tomography is more useful when gastrointestinal or genitourinary pathology is more likely. Magnetic resonance imaging, when available in the acute setting, is favored over computed tomography for assessing pregnant patients for nongynecologic etiologies because of the lack of ionizing radiation.

Urinary Stone Disease during Pregnancy: One Problem, Two Patients

Urolithiasis in pregnant women is a quite uncommon event: about one in 1500 pregnancies is complicated by urinary calculi and it occurs in 80–90% of the patients during the second or third trimester of pregnancy.

Several factors may predispose stone formation in the upper urinary tract during pregnancy: the “physiological” hydronephrosis, the gestational hypercalciuria, and an elevation in both glomerular filtration rate and renal plasma flow, associated with an increase of creatinine clearance and higher renal filtration rate of sodium, calcium, and uric acid. Flank or abdominal pain is the most common symptom associated with evident or microscopic hematuria. Differential diagnosis of pain varies according to its location: it could be of gastrointestinal or gynecologic origin.

Diagnosis is previously based on ultrasound evaluation. The use of radiation must be avoided during pregnancy, even if the risk of fetal injures depends on gestational age and radiation dosage. Most of the symptomatic ureteral stones affecting pregnant women pass spontaneously: therefore therapy could be conservative (hydration, analgesia, antibiotics, antiemetics) in the most of cases, although in the 15–30% of the cases it is necessary to adopt an active treatment, like percutaneous nephrostomy drainage, ureteral stent insertion or ureterorenoscopy.

Management of urinary calculi in pregnancy: a review

Nephrolithiasis during pregnancy can represent a clinical dilemma because of potential risks to both mother and fetus. While the incidence of symptomatic nephrolithiasis during pregnancy varies between 1 in 244 to 1 in 2000 pregnancies, the actual incidence is likely to be higher. A significant proportion of patients with asymptomatic renal calculi are detected incidentally in the nonpregnant population compared with pregnant women. Factors that contribute to the diagnostic challenges include anatomic and physiologic changes to the female urinary tract during pregnancy and the limitations on the use of ionizing radiation. The treatment of such patients requires a multidisciplinary team approach involving the urologist, obstetrician, and radiologist. The potential hazards of intervention (either surgical or medical) and anesthesia need to be considered carefully.

MR urography: techniques and clinical applications

Magnetic resonance (MR) urography comprises an evolving group of techniques with the potential for allowing optimal noninvasive evaluation of many abnormalities of the urinary tract. MR urography is clinically useful in the evaluation of suspected urinary tract obstruction, hematuria, and congenital anomalies, as well as surgically altered anatomy, and can be particularly beneficial in pediatric or pregnant patients or when ionizing radiation is to be avoided. The most common MR urographic techniques for displaying the urinary tract can be divided into two categories: static-fluid MR urography and excretory MR urography. Static-fluid MR urography makes use of heavily T2-weighted sequences to image the urinary tract as a static collection of fluid, can be repeated sequentially (cine MR urography) to better demonstrate the ureters in their entirety and to confirm the presence of fixed stenoses, and is most successful in patients with dilated or obstructed collecting systems. Excretory MR urography is performed during the excretory phase of enhancement after the intravenous administration of gadolinium-based contrast material; thus, the patient must have sufficient renal function to allow the excretion and even distribution of the contrast material. Diuretic administration is an important adjunct to excretory MR urography, which can better demonstrate nondilated systems. Static-fluid and excretory MR urography can be combined with conventional MR imaging for comprehensive evaluation of the urinary tract. The successful interpretation of MR urographic examinations requires familiarity with the many pitfalls and artifacts that can be encountered with these techniques.

Imaging the pregnant patient for nonobstetric conditions: algorithms and radiation dose considerations

Use of diagnostic imaging studies for evaluation of pregnant patients with medical conditions not related to pregnancy poses a persistent and recurring dilemma. Although a theoretical risk of carcinogenesis exists, there are no known risks for development of congenital malformations or mental retardation in a fetus exposed to ionizing radiation at the levels typically used for diagnostic imaging. An understanding of the effects of ionizing radiation on the fetus at different gestational stages and the estimated exposure dose received by the fetus from various imaging modalities facilitates appropriate choices for diagnostic imaging of pregnant patients with nonobstetric conditions. Other aspects of imaging besides radiation (ie, contrast agents) also carry potential for fetal injury and must be taken into consideration. Imaging algorithms based on a review of the current literature have been developed for specific nonobstetric conditions: pulmonary embolism, acute appendicitis, urolithiasis, biliary disease, and trauma. Imaging modalities that do not use ionizing radiation (ie, ultrasonography and magnetic resonance imaging) are preferred for pregnant patients. If ionizing radiation is used, one must adhere to the principle of using a dose that is as low as reasonably achievable after a discussion of risks versus benefits with the patient.

Urologic Radiology During Pregnancy

The pregnant patient presents a unique diagnostic challenge to the urologist because the well-being of both the mother and fetus must be considered. Radiation exposure to the fetus during gestation presents risks such as cell death and teratogenic effects, carcinogenesis, and genetic effects, which must be considered when selecting diagnostic tests. However, with the exercise of good clinical judgment and the use of the armamentarium of diagnostic imaging modalities available, the pregnant patient can be managed with minimal, if any radiation exposure to the fetus.

MR Imaging Evaluation of Acute Abdominal Pain During Pregnancy

MR imaging enables diagnosis of a variety of maternal diseases presenting as acute abdominal pain in pregnant patients. MR imaging is a valuable complement to ultrasound in the determination of the exact etiology of acute abdominal pain, and it is important for the radiologist to recognize the MR imaging appearance of common causes of acute abdominal pain during pregnancy. This article reviews the MR imaging technique and findings of various abnormalities causing acute abdominal pain in pregnant patients.

Urolithiasis in Pregnancy: Current Diagnosis, Treatment, and Pregnancy Complications

Urolithiasis complicates up to one in every 200 pregnancies; consequently, the practicing obstetrician should be aware of the symptoms of urolithiasis, the diagnostic procedures available for its diagnosis, and their associated risks. These include ultrasound, urography, and magnetic resonance imaging. Diagnosis of urolithiasis during pregnancy can be a challenge as a result of the normal physiological changes of pregnancy. Conservative management is the first-line treatment for noncomplicated urolithiasis in pregnancy. If spontaneous passage of the stone does not occur or if complications develop, urologic consultation should be obtained. Several obstetric complications have been associated with urolithiasis, including preterm labor and preterm premature rupture of membranes, although the reported rates of these complications in association with urolithiasis vary widely and overlap normal background rates. Given that urolithiasis will be encountered by most obstetricians, and that obstetricians are often on the front line of management for this condition, an appreciation of current diagnostic modalities, treatment protocols, and associated potential obstetric complications is warranted.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall that urolithiasis is common in pregnancy, state that there are a variety of diagnostic procedures, summarize that conservative treatment is usually successful, and explain that complications of pregnancy usually occur when there is failure of conservative treatment.

Acute non-traumatic maternal illnesses in pregnancy: imaging approaches

The imaging methods used to obtain diagnostic information for pregnant patients presenting with acute non-traumatic maternal illnesses have been reviewed. Conditions affecting the gastrointestinal tract, urinary tract, uterus, adnexae, central nervous system and chest have been investigated via a variety of imaging methods, which include ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), intravenous pyelography (IVP), angiography and fluoroscopy. The method of choice, application, and safety to the mother and fetus are considered for investigation of each condition.

Right-Lower-Quadrant Pain and Suspected Appendicitis in Pregnant Women: Evaluation with MR Imaging—Initial Experience

PURPOSE

To determine if there is a role for magnetic resonance (MR) imaging in evaluation of pregnant women with acute right-lower-quadrant pain in whom acute appendicitis is suspected.

MATERIALS AND METHODS

Informed consent and institutional review board approval were obtained. Images obtained with a 1.5-T MR imager and medical records of 23 pregnant women (age range, 19-34 years; mean age, 24.7 years) who presented with acute right-lower-quadrant pain were retrospectively reviewed. MR protocol included use of transverse, coronal, and sagittal noncontiguous T2-weighted single-shot fast spin-echo (SE) sequences; transverse fat-suppressed T2-weighted fast SE sequences; transverse T1-weighted gradient-recalled-echo sequences; and transverse and coronal short inversion time inversion-recovery sequences performed through the lower abdomen and pelvis. MR findings were evaluated by two radiologists and compared with surgical and pathologic findings and clinical follow-up data.

RESULTS

Appendix was detected in 20 (86.9%) of 23 patients. Seven patients underwent surgery; four had acute appendicitis, and three had ovarian torsion. Two patients with pelvic abscesses not related to appendicitis underwent percutaneous drainage. Fourteen patients were treated medically. Dilated thick-walled appendix and periappendiceal inflammation were detected in three (75%) of four patients with acute appendicitis. In one patient with appendicitis, the appendix could not be visualized, but inflammation was present in the right lower quadrant. In three patients with ovarian torsion, MR imaging demonstrated right adnexal mass or inflammation. MR imaging was used to correctly identify pelvic abscesses and healthy appendix in two patients. A healthy appendix was depicted in 17 (89.5%) of 19 patients without acute appendicitis.

CONCLUSION

MR imaging shows promise for evaluation of pregnant women in whom acute appendicitis is suspected by enabling diagnosis of other possible causes of right-lower-quadrant pain, including ovarian torsion or pelvic abscesses, and demonstrating a healthy or unhealthy appendix.

Diagnostic value of diuretic-enhanced excretory MR urography in patients with obstructive uropathy

PURPOSE

Ultrasonography and conventional intravenous urography are most common methods in diagnosis of obstructive uropathies. The disadvantage of ultrasonography is inability of visualizing middle and lower one thirds of ureter, while intravenous urography is using radiation, also functionally extra loading effect on kidneys. In this study, the diagnostic value of MR urography on obstructive uropathy were investigated.

MATERIALS AND METHODS

Forty five patients who were suffered from obstructive uropathy examined by ultrasonography, intravenous urography and diuretic-enhanced excretory MR urography by using MR-contrast-agent.

RESULTS

MR urography established accuracy rate of 92.8% for stone diseases which formed the largest group in this study, however, in other causes of obstructive uropathy, MR urography provide 100% correct diagnosis.

CONCLUSION

MR urography provide high quality images for diagnosing and determining causes of urinary obstruction defining position and severity of dilatations as well as showing localization of the pathology. We think that MR urography should be a primary investigation in patients with obstructive uropathy who have contrast agent and X-ray contrindication.

Exploration de l’appareil urinaire en IRM : développements actuels et perspectives futures

New fast MR imaging sequences obtained with high power gradients allow dynamic analysis of parenchymal enhancement by contrast media in order to improve characterization of masses as well as a functional analysis. Phased - array coils have greatly improved spatial resolution. MR Urography is a new valuable modality to study the collecting system. Numerous acronyms are proposed with a wide range of variations between different machines. But basic principles for sequences are similar. MR can be performed in patients with renal insufficiency, iodine allergy or any other contra-indication to the use of ionizing radiation. MRI of the kidney is becoming a major imaging modality to diagnose diseases of the kidney. It provides in a rather short time a "all-in-one approach" of the pathological process.

Evaluation of Painful Hydronephrosis in Pregnancy:: Magnetic Resonance Urographic Patterns in Physiological Dilatation Versus Calculous Obstruction

PURPOSE

We evaluated magnetic resonance urography (MRU) appearances in symptomatic hydronephrosis in pregnancy and compared urographic patterns in physiological and calculous disease.

MATERIALS AND METHODS

A total of 24 consecutive pregnant women with symptomatic hydronephrosis underwent MRU, comprising an overview fast T2-weighted examination of the abdomen and pelvis, and thick slab, heavily T2-weighted MRU images, followed by focused, high resolution T2-weighted sequences obtained in an axial and coronal oblique plane through the level of ureteral caliber change.

RESULTS

Of these 24 pregnant women 15 were found to have physiological hydronephrosis, 7 had calculous disease and 2 had preexisting urinary anomalies. MRU findings in physiological hydronephrosis cases were extrinsic compression of the middle third of the ureter, no filling defect and a collapsed ureter below it. Obstruction by ureteral calculi was seen at points of ureteral narrowing in the ureter, that is at the vesicoureteral junction in 2 cases, in the compressed mid ureter in 3 and at the pelviureteral junction in 1. Nonobstructive renal calculi were seen in another patient. Calculi presented throughout pregnancy but physiological hydronephrosis presented only in the late second and third trimesters. With distal calculi the MRU appearance was the double kink sign with constriction at the pelvic brim and the vesicoureteral junction with a standing column of urine in the pelvic ureter. There was renal edema and perirenal extravasation. Small calculi were only identified using high resolution T2-weighted magnetic resonance imaging.

CONCLUSIONS

MRU is a valuable and well tolerated investigation for evaluating painful hydronephrosis in pregnancy. There are characteristic and differing urographic appearances in physiological and calculous obstruction.

Evaluation of the patient with flank pain and possible ureteral calculus

Flank pain due to urolithiasis is a common problem in patients presenting to emergency departments. Radiology plays a vital role in the work-up of these patients. Many modalities can be used, including ultrasonography, nuclear medicine, and the traditionally used techniques of intravenous urography and conventional radiography. The development of nonenhanced computed tomography (CT) (single- or multi-detector row helical) has provided a means to enable detection and characterization of urolithiasis with unprecedented sensitivity, specificity, and accuracy while yielding important information for treatment planning, including the size and location of calculi. This technique can also help detect causes for flank pain outside the genitourinary tract. However, close attention must be paid to all aspects of the CT study to prevent misdiagnoses.

Patients with acute flank pain: comparison of MR urography with unenhanced helical CT

PURPOSE

To compare unenhanced helical computed tomography (CT) and magnetic resonance (MR) urography, by using T2-weighted and contrast material-enhanced T1-weighted imaging to examine patients with acute flank pain, with reference to excretory urography and final clinical diagnosis.

MATERIALS AND METHODS

Forty-nine patients underwent CT, MR urography (with T2-weighted and gadopentetate dimeglumine-enhanced T1-weighted sequences), and excretory urography. CT and MR urographic findings were evaluated separately and independently by two radiologists each (CT, observers A and B; MR urography, observers C and D) for the presence, cause, level, and degree of obstruction. The final conclusive diagnosis was based on the combination of excretory urographic, clinical, and interventional results.

RESULTS

At final diagnosis, 32 (65%) patients were found to have ureteral stones causing unilateral obstruction. In ureteral stone detection, the sensitivity and specificity of CT were 90.6% (29 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer A) and 90.6% (29 of 32 patients) and 94.1% (16 of 17 patients), respectively (observer B), while those of MR urography were 93.8% (30 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer C) and 100.0% (32 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer D). Spearman correlation coefficients for stone size at CT were 0.76 (P <.001) and 0.75 (P <.001) and at MR urography, 0.49 (P =.005) and 0.51 (P =.004).

CONCLUSION

In routine clinical practice, CT is the modality of choice in the evaluation of patients with acute flank pain. MR urography is an accurate and suitable alternative imaging technique in selected patients.

MR urography in evaluation of acute flank pain: T2-weighted sequences and gadolinium-enhanced three-dimensional FLASH compared with urography. Fast low-angle shot

OBJECTIVE

The aim of this study was to compare the usefulness of breath-hold heavily T2-weighted sequences with gadolinium-enhanced three-dimensional fast low-angle shot (3D FLASH) MR urography in the evaluation of patients with acute flank pain.

SUBJECTS AND METHODS

Forty consecutive patients with symptoms of acute flank pain underwent MR urography followed immediately by excretory urography. Heavily T2-weighted (combined thin-slice half-Fourier acquisition single-shot turbo spin-echo [HASTE] and thick-slab single-shot turbo spin-echo) and 3D FLASH sequences were evaluated separately and independently by two experienced radiologists for the presence, cause, level, and degree of obstruction. Interobserver agreement was calculated using the kappa statistic. Excretory urography and the final clinical diagnosis were used as reference.

RESULTS

Twenty-six patients were found to have unilateral obstruction caused by ureteral stones. Both MR urography methods were excellent for detecting obstruction. In the detection of stones 3D FLASH was superior, with a sensitivity of 96.2% and 100% and specificity of 100% and 100% for observers A and B, respectively, compared with a sensitivity of 57.7% and 53.8% and a specificity of 100% and 100%, respectively, for T2-weighted sequences. The best degree of obstruction was seen with 3D FLASH, and the interobserver agreement was excellent for stone detection (kappa = 0.97).

CONCLUSION

T2-weighted sequences alone are not sufficient for examining patients with acute flank pain. However, the combined use of both T2-weighted and 3D FLASH sequences will ensure better confidence in the evaluation of acute suspected renal colic. MR urography can replace conventional excretory urography when the latter is contraindicated or undesirable.

Spinal dysraphism at MR urography: initial experience

PURPOSE

To prospectively evaluate the role of magnetic resonance (MR) urography in the radiologic assessment of patients with spinal dysraphism.

MATERIALS AND METHODS

Fourteen patients with spinal dysraphism were referred for MR urography with half-Fourier rapid acquisition with relaxation enhancement (RARE) (repetition time msec/echo time msec = 11.9/95) and RARE (2,800/1,100) sequences on a 1.5-T MR machine. Six patients did not tolerate MR urography owing to claustrophobia (n = 4) or flexion deformities (n = 2), giving a final success rate of 57% (eight patients). Two patients had a single kidney (one after nephrectomy, one with a crossed-fused ectopic kidney). Images were jointly assessed by two radiologists and compared with excretory urographic studies. The signal intensity ratio and contrast-to-noise ratio were also calculated.

RESULTS

Visualization of the kidneys, pelvicaliceal system, and ureters was better with half-Fourier RARE than with RARE imaging, whereas visualization of the bladder was comparable with both sequences. The mean signal intensity ratios for half-Fourier RARE and RARE sequences, respectively, were 16.2 +/- 3.65 and 19.2 +/- 3.65 (P =. 58, factorial analysis of variance model), whereas the mean contrast-to-noise ratios were 55.4 +/- 5.16 and 47.8 +/- 5.16 (P =. 34). Cortical scarring was depicted more clearly at MR urography than at excretory urography, whereas a renal calculus seen at excretory urography was not detected at MR urography.

CONCLUSION

MR urography was feasible in 57% of patients with spinal dysraphism and is a safe, accurate method of evaluating the upper urinary tract.